Squashed 'lib/mbedtls/external/mbedtls/' content from commit 2ca6c285a0dd

git-subtree-dir: lib/mbedtls/external/mbedtls
git-subtree-split: 2ca6c285a0dd3f33982dd57299012dacab1ff206
diff --git a/programs/x509/CMakeLists.txt b/programs/x509/CMakeLists.txt
new file mode 100644
index 0000000..43437f0
--- /dev/null
+++ b/programs/x509/CMakeLists.txt
@@ -0,0 +1,24 @@
+set(libs
+    ${mbedx509_target}
+)
+
+set(executables
+    cert_app
+    cert_req
+    cert_write
+    crl_app
+    load_roots
+    req_app
+)
+
+foreach(exe IN LISTS executables)
+    add_executable(${exe} ${exe}.c $<TARGET_OBJECTS:mbedtls_test>)
+    target_link_libraries(${exe} ${libs} ${CMAKE_THREAD_LIBS_INIT})
+    target_include_directories(${exe} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../../tests/include)
+endforeach()
+
+target_link_libraries(cert_app ${mbedtls_target})
+
+install(TARGETS ${executables}
+        DESTINATION "bin"
+        PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
diff --git a/programs/x509/cert_app.c b/programs/x509/cert_app.c
new file mode 100644
index 0000000..cb1e5bc
--- /dev/null
+++ b/programs/x509/cert_app.c
@@ -0,0 +1,456 @@
+/*
+ *  Certificate reading application
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include "mbedtls/build_info.h"
+
+#include "mbedtls/platform.h"
+
+#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_ENTROPY_C) ||  \
+    !defined(MBEDTLS_SSL_TLS_C) || !defined(MBEDTLS_SSL_CLI_C) || \
+    !defined(MBEDTLS_NET_C) || !defined(MBEDTLS_RSA_C) ||         \
+    !defined(MBEDTLS_X509_CRT_PARSE_C) || !defined(MBEDTLS_FS_IO) ||  \
+    !defined(MBEDTLS_CTR_DRBG_C) || defined(MBEDTLS_X509_REMOVE_INFO)
+int main(void)
+{
+    mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_ENTROPY_C and/or "
+                   "MBEDTLS_SSL_TLS_C and/or MBEDTLS_SSL_CLI_C and/or "
+                   "MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
+                   "MBEDTLS_X509_CRT_PARSE_C and/or MBEDTLS_FS_IO and/or "
+                   "MBEDTLS_CTR_DRBG_C not defined and/or MBEDTLS_X509_REMOVE_INFO defined.\n");
+    mbedtls_exit(0);
+}
+#else
+
+#include "mbedtls/entropy.h"
+#include "mbedtls/ctr_drbg.h"
+#include "mbedtls/net_sockets.h"
+#include "mbedtls/ssl.h"
+#include "mbedtls/x509.h"
+#include "mbedtls/debug.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MODE_NONE               0
+#define MODE_FILE               1
+#define MODE_SSL                2
+
+#define DFL_MODE                MODE_NONE
+#define DFL_FILENAME            "cert.crt"
+#define DFL_CA_FILE             ""
+#define DFL_CRL_FILE            ""
+#define DFL_CA_PATH             ""
+#define DFL_SERVER_NAME         "localhost"
+#define DFL_SERVER_PORT         "4433"
+#define DFL_DEBUG_LEVEL         0
+#define DFL_PERMISSIVE          0
+
+#define USAGE_IO \
+    "    ca_file=%%s          The single file containing the top-level CA(s) you fully trust\n" \
+    "                        default: \"\" (none)\n" \
+    "    crl_file=%%s         The single CRL file you want to use\n" \
+    "                        default: \"\" (none)\n" \
+    "    ca_path=%%s          The path containing the top-level CA(s) you fully trust\n" \
+    "                        default: \"\" (none) (overrides ca_file)\n"
+
+#define USAGE \
+    "\n usage: cert_app param=<>...\n"                  \
+    "\n acceptable parameters:\n"                       \
+    "    mode=file|ssl       default: none\n"           \
+    "    filename=%%s         default: cert.crt\n"      \
+    USAGE_IO                                            \
+    "    server_name=%%s      default: localhost\n"     \
+    "    server_port=%%d      default: 4433\n"          \
+    "    debug_level=%%d      default: 0 (disabled)\n"  \
+    "    permissive=%%d       default: 0 (disabled)\n"  \
+    "\n"
+
+
+/*
+ * global options
+ */
+struct options {
+    int mode;                   /* the mode to run the application in   */
+    const char *filename;       /* filename of the certificate file     */
+    const char *ca_file;        /* the file with the CA certificate(s)  */
+    const char *crl_file;       /* the file with the CRL to use         */
+    const char *ca_path;        /* the path with the CA certificate(s) reside */
+    const char *server_name;    /* hostname of the server (client only) */
+    const char *server_port;    /* port on which the ssl service runs   */
+    int debug_level;            /* level of debugging                   */
+    int permissive;             /* permissive parsing                   */
+} opt;
+
+static void my_debug(void *ctx, int level,
+                     const char *file, int line,
+                     const char *str)
+{
+    ((void) level);
+
+    mbedtls_fprintf((FILE *) ctx, "%s:%04d: %s", file, line, str);
+    fflush((FILE *) ctx);
+}
+
+static int my_verify(void *data, mbedtls_x509_crt *crt, int depth, uint32_t *flags)
+{
+    char buf[1024];
+    ((void) data);
+
+    mbedtls_printf("\nVerify requested for (Depth %d):\n", depth);
+    mbedtls_x509_crt_info(buf, sizeof(buf) - 1, "", crt);
+    mbedtls_printf("%s", buf);
+
+    if ((*flags) == 0) {
+        mbedtls_printf("  This certificate has no flags\n");
+    } else {
+        mbedtls_x509_crt_verify_info(buf, sizeof(buf), "  ! ", *flags);
+        mbedtls_printf("%s\n", buf);
+    }
+
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    int ret = 1;
+    int exit_code = MBEDTLS_EXIT_FAILURE;
+    mbedtls_net_context server_fd;
+    unsigned char buf[1024];
+    mbedtls_entropy_context entropy;
+    mbedtls_ctr_drbg_context ctr_drbg;
+    mbedtls_ssl_context ssl;
+    mbedtls_ssl_config conf;
+    mbedtls_x509_crt cacert;
+    mbedtls_x509_crl cacrl;
+    int i, j;
+    uint32_t flags;
+    int verify = 0;
+    char *p, *q;
+    const char *pers = "cert_app";
+
+    /*
+     * Set to sane values
+     */
+    mbedtls_net_init(&server_fd);
+    mbedtls_ctr_drbg_init(&ctr_drbg);
+    mbedtls_ssl_init(&ssl);
+    mbedtls_ssl_config_init(&conf);
+    mbedtls_x509_crt_init(&cacert);
+    mbedtls_entropy_init(&entropy);
+#if defined(MBEDTLS_X509_CRL_PARSE_C)
+    mbedtls_x509_crl_init(&cacrl);
+#else
+    /* Zeroize structure as CRL parsing is not supported and we have to pass
+       it to the verify function */
+    memset(&cacrl, 0, sizeof(mbedtls_x509_crl));
+#endif
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_status_t status = psa_crypto_init();
+    if (status != PSA_SUCCESS) {
+        mbedtls_fprintf(stderr, "Failed to initialize PSA Crypto implementation: %d\n",
+                        (int) status);
+        goto exit;
+    }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    if (argc < 2) {
+usage:
+        mbedtls_printf(USAGE);
+        goto exit;
+    }
+
+    opt.mode                = DFL_MODE;
+    opt.filename            = DFL_FILENAME;
+    opt.ca_file             = DFL_CA_FILE;
+    opt.crl_file            = DFL_CRL_FILE;
+    opt.ca_path             = DFL_CA_PATH;
+    opt.server_name         = DFL_SERVER_NAME;
+    opt.server_port         = DFL_SERVER_PORT;
+    opt.debug_level         = DFL_DEBUG_LEVEL;
+    opt.permissive          = DFL_PERMISSIVE;
+
+    for (i = 1; i < argc; i++) {
+        p = argv[i];
+        if ((q = strchr(p, '=')) == NULL) {
+            goto usage;
+        }
+        *q++ = '\0';
+
+        for (j = 0; p + j < q; j++) {
+            if (argv[i][j] >= 'A' && argv[i][j] <= 'Z') {
+                argv[i][j] |= 0x20;
+            }
+        }
+
+        if (strcmp(p, "mode") == 0) {
+            if (strcmp(q, "file") == 0) {
+                opt.mode = MODE_FILE;
+            } else if (strcmp(q, "ssl") == 0) {
+                opt.mode = MODE_SSL;
+            } else {
+                goto usage;
+            }
+        } else if (strcmp(p, "filename") == 0) {
+            opt.filename = q;
+        } else if (strcmp(p, "ca_file") == 0) {
+            opt.ca_file = q;
+        } else if (strcmp(p, "crl_file") == 0) {
+            opt.crl_file = q;
+        } else if (strcmp(p, "ca_path") == 0) {
+            opt.ca_path = q;
+        } else if (strcmp(p, "server_name") == 0) {
+            opt.server_name = q;
+        } else if (strcmp(p, "server_port") == 0) {
+            opt.server_port = q;
+        } else if (strcmp(p, "debug_level") == 0) {
+            opt.debug_level = atoi(q);
+            if (opt.debug_level < 0 || opt.debug_level > 65535) {
+                goto usage;
+            }
+        } else if (strcmp(p, "permissive") == 0) {
+            opt.permissive = atoi(q);
+            if (opt.permissive < 0 || opt.permissive > 1) {
+                goto usage;
+            }
+        } else {
+            goto usage;
+        }
+    }
+
+    /*
+     * 1.1. Load the trusted CA
+     */
+    mbedtls_printf("  . Loading the CA root certificate ...");
+    fflush(stdout);
+
+    if (strlen(opt.ca_path)) {
+        if ((ret = mbedtls_x509_crt_parse_path(&cacert, opt.ca_path)) < 0) {
+            mbedtls_printf(" failed\n  !  mbedtls_x509_crt_parse_path returned -0x%x\n\n",
+                           (unsigned int) -ret);
+            goto exit;
+        }
+
+        verify = 1;
+    } else if (strlen(opt.ca_file)) {
+        if ((ret = mbedtls_x509_crt_parse_file(&cacert, opt.ca_file)) < 0) {
+            mbedtls_printf(" failed\n  !  mbedtls_x509_crt_parse_file returned -0x%x\n\n",
+                           (unsigned int) -ret);
+            goto exit;
+        }
+
+        verify = 1;
+    }
+
+    mbedtls_printf(" ok (%d skipped)\n", ret);
+
+#if defined(MBEDTLS_X509_CRL_PARSE_C)
+    if (strlen(opt.crl_file)) {
+        if ((ret = mbedtls_x509_crl_parse_file(&cacrl, opt.crl_file)) != 0) {
+            mbedtls_printf(" failed\n  !  mbedtls_x509_crl_parse returned -0x%x\n\n",
+                           (unsigned int) -ret);
+            goto exit;
+        }
+
+        verify = 1;
+    }
+#endif
+
+    if (opt.mode == MODE_FILE) {
+        mbedtls_x509_crt crt;
+        mbedtls_x509_crt *cur = &crt;
+        mbedtls_x509_crt_init(&crt);
+
+        /*
+         * 1.1. Load the certificate(s)
+         */
+        mbedtls_printf("\n  . Loading the certificate(s) ...");
+        fflush(stdout);
+
+        ret = mbedtls_x509_crt_parse_file(&crt, opt.filename);
+
+        if (ret < 0) {
+            mbedtls_printf(" failed\n  !  mbedtls_x509_crt_parse_file returned %d\n\n", ret);
+            mbedtls_x509_crt_free(&crt);
+            goto exit;
+        }
+
+        if (opt.permissive == 0 && ret > 0) {
+            mbedtls_printf(
+                " failed\n  !  mbedtls_x509_crt_parse failed to parse %d certificates\n\n",
+                ret);
+            mbedtls_x509_crt_free(&crt);
+            goto exit;
+        }
+
+        mbedtls_printf(" ok\n");
+
+        /*
+         * 1.2 Print the certificate(s)
+         */
+        while (cur != NULL) {
+            mbedtls_printf("  . Peer certificate information    ...\n");
+            ret = mbedtls_x509_crt_info((char *) buf, sizeof(buf) - 1, "      ",
+                                        cur);
+            if (ret == -1) {
+                mbedtls_printf(" failed\n  !  mbedtls_x509_crt_info returned %d\n\n", ret);
+                mbedtls_x509_crt_free(&crt);
+                goto exit;
+            }
+
+            mbedtls_printf("%s\n", buf);
+
+            cur = cur->next;
+        }
+
+        /*
+         * 1.3 Verify the certificate
+         */
+        if (verify) {
+            mbedtls_printf("  . Verifying X.509 certificate...");
+
+            if ((ret = mbedtls_x509_crt_verify(&crt, &cacert, &cacrl, NULL, &flags,
+                                               my_verify, NULL)) != 0) {
+                char vrfy_buf[512];
+
+                mbedtls_printf(" failed\n");
+
+                mbedtls_x509_crt_verify_info(vrfy_buf, sizeof(vrfy_buf), "  ! ", flags);
+
+                mbedtls_printf("%s\n", vrfy_buf);
+            } else {
+                mbedtls_printf(" ok\n");
+            }
+        }
+
+        mbedtls_x509_crt_free(&crt);
+    } else if (opt.mode == MODE_SSL) {
+        /*
+         * 1. Initialize the RNG and the session data
+         */
+        mbedtls_printf("\n  . Seeding the random number generator...");
+        fflush(stdout);
+
+        if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
+                                         (const unsigned char *) pers,
+                                         strlen(pers))) != 0) {
+            mbedtls_printf(" failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret);
+            goto ssl_exit;
+        }
+
+        mbedtls_printf(" ok\n");
+
+#if defined(MBEDTLS_DEBUG_C)
+        mbedtls_debug_set_threshold(opt.debug_level);
+#endif
+
+        /*
+         * 2. Start the connection
+         */
+        mbedtls_printf("  . SSL connection to tcp/%s/%s...", opt.server_name,
+                       opt.server_port);
+        fflush(stdout);
+
+        if ((ret = mbedtls_net_connect(&server_fd, opt.server_name,
+                                       opt.server_port, MBEDTLS_NET_PROTO_TCP)) != 0) {
+            mbedtls_printf(" failed\n  ! mbedtls_net_connect returned %d\n\n", ret);
+            goto ssl_exit;
+        }
+
+        /*
+         * 3. Setup stuff
+         */
+        if ((ret = mbedtls_ssl_config_defaults(&conf,
+                                               MBEDTLS_SSL_IS_CLIENT,
+                                               MBEDTLS_SSL_TRANSPORT_STREAM,
+                                               MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
+            mbedtls_printf(" failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret);
+            goto exit;
+        }
+
+        if (verify) {
+            mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_REQUIRED);
+            mbedtls_ssl_conf_ca_chain(&conf, &cacert, NULL);
+            mbedtls_ssl_conf_verify(&conf, my_verify, NULL);
+        } else {
+            mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_NONE);
+        }
+
+        mbedtls_ssl_conf_rng(&conf, mbedtls_ctr_drbg_random, &ctr_drbg);
+        mbedtls_ssl_conf_dbg(&conf, my_debug, stdout);
+
+        if ((ret = mbedtls_ssl_setup(&ssl, &conf)) != 0) {
+            mbedtls_printf(" failed\n  ! mbedtls_ssl_setup returned %d\n\n", ret);
+            goto ssl_exit;
+        }
+
+        if ((ret = mbedtls_ssl_set_hostname(&ssl, opt.server_name)) != 0) {
+            mbedtls_printf(" failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n", ret);
+            goto ssl_exit;
+        }
+
+        mbedtls_ssl_set_bio(&ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv, NULL);
+
+        /*
+         * 4. Handshake
+         */
+        while ((ret = mbedtls_ssl_handshake(&ssl)) != 0) {
+            if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
+                mbedtls_printf(" failed\n  ! mbedtls_ssl_handshake returned %d\n\n", ret);
+                goto ssl_exit;
+            }
+        }
+
+        mbedtls_printf(" ok\n");
+
+        /*
+         * 5. Print the certificate
+         */
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+        mbedtls_printf("  . Peer certificate information    ... skipped\n");
+#else
+        mbedtls_printf("  . Peer certificate information    ...\n");
+        ret = mbedtls_x509_crt_info((char *) buf, sizeof(buf) - 1, "      ",
+                                    mbedtls_ssl_get_peer_cert(&ssl));
+        if (ret == -1) {
+            mbedtls_printf(" failed\n  !  mbedtls_x509_crt_info returned %d\n\n", ret);
+            goto ssl_exit;
+        }
+
+        mbedtls_printf("%s\n", buf);
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+        mbedtls_ssl_close_notify(&ssl);
+
+ssl_exit:
+        mbedtls_ssl_free(&ssl);
+        mbedtls_ssl_config_free(&conf);
+    } else {
+        goto usage;
+    }
+
+    exit_code = MBEDTLS_EXIT_SUCCESS;
+
+exit:
+
+    mbedtls_net_free(&server_fd);
+    mbedtls_x509_crt_free(&cacert);
+#if defined(MBEDTLS_X509_CRL_PARSE_C)
+    mbedtls_x509_crl_free(&cacrl);
+#endif
+    mbedtls_ctr_drbg_free(&ctr_drbg);
+    mbedtls_entropy_free(&entropy);
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_psa_crypto_free();
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    mbedtls_exit(exit_code);
+}
+#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C && MBEDTLS_SSL_TLS_C &&
+          MBEDTLS_SSL_CLI_C && MBEDTLS_NET_C && MBEDTLS_RSA_C &&
+          MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_FS_IO && MBEDTLS_CTR_DRBG_C */
diff --git a/programs/x509/cert_req.c b/programs/x509/cert_req.c
new file mode 100644
index 0000000..dcfd176
--- /dev/null
+++ b/programs/x509/cert_req.c
@@ -0,0 +1,514 @@
+/*
+ *  Certificate request generation
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include "mbedtls/build_info.h"
+
+#include "mbedtls/platform.h"
+/* md.h is included this early since MD_CAN_XXX macros are defined there. */
+#include "mbedtls/md.h"
+
+#if !defined(MBEDTLS_X509_CSR_WRITE_C) || !defined(MBEDTLS_X509_CRT_PARSE_C) || \
+    !defined(MBEDTLS_PK_PARSE_C) || !defined(MBEDTLS_MD_CAN_SHA256) || \
+    !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C) || \
+    !defined(MBEDTLS_PEM_WRITE_C) || !defined(MBEDTLS_FS_IO) || \
+    !defined(MBEDTLS_MD_C)
+int main(void)
+{
+    mbedtls_printf("MBEDTLS_X509_CSR_WRITE_C and/or MBEDTLS_FS_IO and/or "
+                   "MBEDTLS_PK_PARSE_C and/or MBEDTLS_MD_CAN_SHA256 and/or "
+                   "MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C "
+                   "not defined.\n");
+    mbedtls_exit(0);
+}
+#else
+
+#include "mbedtls/x509_csr.h"
+#include "mbedtls/entropy.h"
+#include "mbedtls/ctr_drbg.h"
+#include "mbedtls/error.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DFL_FILENAME            "keyfile.key"
+#define DFL_PASSWORD            NULL
+#define DFL_DEBUG_LEVEL         0
+#define DFL_OUTPUT_FILENAME     "cert.req"
+#define DFL_SUBJECT_NAME        "CN=Cert,O=mbed TLS,C=UK"
+#define DFL_KEY_USAGE           0
+#define DFL_FORCE_KEY_USAGE     0
+#define DFL_NS_CERT_TYPE        0
+#define DFL_FORCE_NS_CERT_TYPE  0
+#define DFL_MD_ALG              MBEDTLS_MD_SHA256
+
+#define USAGE \
+    "\n usage: cert_req param=<>...\n"                  \
+    "\n acceptable parameters:\n"                       \
+    "    filename=%%s         default: keyfile.key\n"   \
+    "    password=%%s         default: NULL\n"          \
+    "    debug_level=%%d      default: 0 (disabled)\n"  \
+    "    output_file=%%s      default: cert.req\n"      \
+    "    subject_name=%%s     default: CN=Cert,O=mbed TLS,C=UK\n"   \
+    "    san=%%s              default: (none)\n"       \
+    "                           Semicolon-separated-list of values:\n" \
+    "                           DNS:value\n"            \
+    "                           URI:value\n"            \
+    "                           RFC822:value\n"         \
+    "                           IP:value (Only IPv4 is supported)\n" \
+    "                           DN:list of comma separated key=value pairs\n" \
+    "    key_usage=%%s        default: (empty)\n"       \
+    "                        Comma-separated-list of values:\n"     \
+    "                          digital_signature\n"     \
+    "                          non_repudiation\n"       \
+    "                          key_encipherment\n"      \
+    "                          data_encipherment\n"     \
+    "                          key_agreement\n"         \
+    "                          key_cert_sign\n"  \
+    "                          crl_sign\n"              \
+    "    force_key_usage=0/1  default: off\n"           \
+    "                          Add KeyUsage even if it is empty\n"  \
+    "    ns_cert_type=%%s     default: (empty)\n"       \
+    "                        Comma-separated-list of values:\n"     \
+    "                          ssl_client\n"            \
+    "                          ssl_server\n"            \
+    "                          email\n"                 \
+    "                          object_signing\n"        \
+    "                          ssl_ca\n"                \
+    "                          email_ca\n"              \
+    "                          object_signing_ca\n"     \
+    "    force_ns_cert_type=0/1 default: off\n"         \
+    "                          Add NsCertType even if it is empty\n"    \
+    "    md=%%s               default: SHA256\n"       \
+    "                          possible values:\n"     \
+    "                          MD5, RIPEMD160, SHA1,\n" \
+    "                          SHA224, SHA256, SHA384, SHA512\n" \
+    "\n"
+
+
+/*
+ * global options
+ */
+struct options {
+    const char *filename;             /* filename of the key file             */
+    const char *password;             /* password for the key file            */
+    int debug_level;                  /* level of debugging                   */
+    const char *output_file;          /* where to store the constructed key file  */
+    const char *subject_name;         /* subject name for certificate request   */
+    mbedtls_x509_san_list *san_list;  /* subjectAltName for certificate request */
+    unsigned char key_usage;          /* key usage flags                      */
+    int force_key_usage;              /* Force adding the KeyUsage extension  */
+    unsigned char ns_cert_type;       /* NS cert type                         */
+    int force_ns_cert_type;           /* Force adding NsCertType extension    */
+    mbedtls_md_type_t md_alg;         /* Hash algorithm used for signature.   */
+} opt;
+
+int write_certificate_request(mbedtls_x509write_csr *req, const char *output_file,
+                              int (*f_rng)(void *, unsigned char *, size_t),
+                              void *p_rng)
+{
+    int ret;
+    FILE *f;
+    unsigned char output_buf[4096];
+    size_t len = 0;
+
+    memset(output_buf, 0, 4096);
+    if ((ret = mbedtls_x509write_csr_pem(req, output_buf, 4096, f_rng, p_rng)) < 0) {
+        return ret;
+    }
+
+    len = strlen((char *) output_buf);
+
+    if ((f = fopen(output_file, "w")) == NULL) {
+        return -1;
+    }
+
+    if (fwrite(output_buf, 1, len, f) != len) {
+        fclose(f);
+        return -1;
+    }
+
+    fclose(f);
+
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    int ret = 1;
+    int exit_code = MBEDTLS_EXIT_FAILURE;
+    mbedtls_pk_context key;
+    char buf[1024];
+    int i;
+    char *p, *q, *r;
+    mbedtls_x509write_csr req;
+    mbedtls_entropy_context entropy;
+    mbedtls_ctr_drbg_context ctr_drbg;
+    const char *pers = "csr example app";
+    mbedtls_x509_san_list *cur, *prev;
+    mbedtls_asn1_named_data *ext_san_dirname = NULL;
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+    uint8_t ip[4] = { 0 };
+#endif
+    /*
+     * Set to sane values
+     */
+    mbedtls_x509write_csr_init(&req);
+    mbedtls_pk_init(&key);
+    mbedtls_ctr_drbg_init(&ctr_drbg);
+    memset(buf, 0, sizeof(buf));
+    mbedtls_entropy_init(&entropy);
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_status_t status = psa_crypto_init();
+    if (status != PSA_SUCCESS) {
+        mbedtls_fprintf(stderr, "Failed to initialize PSA Crypto implementation: %d\n",
+                        (int) status);
+        goto exit;
+    }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    if (argc < 2) {
+usage:
+        mbedtls_printf(USAGE);
+        goto exit;
+    }
+
+    opt.filename            = DFL_FILENAME;
+    opt.password            = DFL_PASSWORD;
+    opt.debug_level         = DFL_DEBUG_LEVEL;
+    opt.output_file         = DFL_OUTPUT_FILENAME;
+    opt.subject_name        = DFL_SUBJECT_NAME;
+    opt.key_usage           = DFL_KEY_USAGE;
+    opt.force_key_usage     = DFL_FORCE_KEY_USAGE;
+    opt.ns_cert_type        = DFL_NS_CERT_TYPE;
+    opt.force_ns_cert_type  = DFL_FORCE_NS_CERT_TYPE;
+    opt.md_alg              = DFL_MD_ALG;
+    opt.san_list            = NULL;
+
+    for (i = 1; i < argc; i++) {
+        p = argv[i];
+        if ((q = strchr(p, '=')) == NULL) {
+            goto usage;
+        }
+        *q++ = '\0';
+        if (strcmp(p, "filename") == 0) {
+            opt.filename = q;
+        } else if (strcmp(p, "password") == 0) {
+            opt.password = q;
+        } else if (strcmp(p, "output_file") == 0) {
+            opt.output_file = q;
+        } else if (strcmp(p, "debug_level") == 0) {
+            opt.debug_level = atoi(q);
+            if (opt.debug_level < 0 || opt.debug_level > 65535) {
+                goto usage;
+            }
+        } else if (strcmp(p, "subject_name") == 0) {
+            opt.subject_name = q;
+        } else if (strcmp(p, "san") == 0) {
+            char *subtype_value;
+            prev = NULL;
+
+            while (q != NULL) {
+                char *semicolon;
+                r = q;
+
+                /* Find the first non-escaped ; occurrence and remove escaped ones */
+                do {
+                    if ((semicolon = strchr(r, ';')) != NULL) {
+                        if (*(semicolon-1) != '\\') {
+                            r = semicolon;
+                            break;
+                        }
+                        /* Remove the escape character */
+                        size_t size_left = strlen(semicolon);
+                        memmove(semicolon-1, semicolon, size_left);
+                        *(semicolon + size_left - 1) = '\0';
+                        /* r will now point at the character after the semicolon */
+                        r = semicolon;
+                    }
+
+                } while (semicolon != NULL);
+
+                if (semicolon != NULL) {
+                    *r++ = '\0';
+                } else {
+                    r = NULL;
+                }
+
+                cur = mbedtls_calloc(1, sizeof(mbedtls_x509_san_list));
+                if (cur == NULL) {
+                    mbedtls_printf("Not enough memory for subjectAltName list\n");
+                    goto usage;
+                }
+
+                cur->next = NULL;
+
+                if ((subtype_value = strchr(q, ':')) != NULL) {
+                    *subtype_value++ = '\0';
+                } else {
+                    mbedtls_printf(
+                        "Invalid argument for option SAN: Entry must be of the form TYPE:value\n");
+                    goto usage;
+                }
+                if (strcmp(q, "RFC822") == 0) {
+                    cur->node.type = MBEDTLS_X509_SAN_RFC822_NAME;
+                } else if (strcmp(q, "URI") == 0) {
+                    cur->node.type = MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER;
+                } else if (strcmp(q, "DNS") == 0) {
+                    cur->node.type = MBEDTLS_X509_SAN_DNS_NAME;
+                } else if (strcmp(q, "IP") == 0) {
+                    size_t ip_addr_len = 0;
+                    cur->node.type = MBEDTLS_X509_SAN_IP_ADDRESS;
+                    ip_addr_len = mbedtls_x509_crt_parse_cn_inet_pton(subtype_value, ip);
+                    if (ip_addr_len == 0) {
+                        mbedtls_printf("mbedtls_x509_crt_parse_cn_inet_pton failed to parse %s\n",
+                                       subtype_value);
+                        goto exit;
+                    }
+                    cur->node.san.unstructured_name.p = (unsigned char *) ip;
+                    cur->node.san.unstructured_name.len = sizeof(ip);
+                } else if (strcmp(q, "DN") == 0) {
+                    cur->node.type = MBEDTLS_X509_SAN_DIRECTORY_NAME;
+                    if ((ret = mbedtls_x509_string_to_names(&ext_san_dirname,
+                                                            subtype_value)) != 0) {
+                        mbedtls_strerror(ret, buf, sizeof(buf));
+                        mbedtls_printf(
+                            " failed\n  !  mbedtls_x509_string_to_names "
+                            "returned -0x%04x - %s\n\n",
+                            (unsigned int) -ret, buf);
+                        goto exit;
+                    }
+                    cur->node.san.directory_name = *ext_san_dirname;
+                } else {
+                    mbedtls_free(cur);
+                    goto usage;
+                }
+
+                if (cur->node.type == MBEDTLS_X509_SAN_RFC822_NAME ||
+                    cur->node.type == MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER ||
+                    cur->node.type == MBEDTLS_X509_SAN_DNS_NAME) {
+                    q = subtype_value;
+                    cur->node.san.unstructured_name.p = (unsigned char *) q;
+                    cur->node.san.unstructured_name.len = strlen(q);
+                }
+
+                if (prev == NULL) {
+                    opt.san_list = cur;
+                } else {
+                    prev->next = cur;
+                }
+
+                prev = cur;
+                q = r;
+            }
+        } else if (strcmp(p, "md") == 0) {
+            const mbedtls_md_info_t *md_info =
+                mbedtls_md_info_from_string(q);
+            if (md_info == NULL) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+            opt.md_alg = mbedtls_md_get_type(md_info);
+        } else if (strcmp(p, "key_usage") == 0) {
+            while (q != NULL) {
+                if ((r = strchr(q, ',')) != NULL) {
+                    *r++ = '\0';
+                }
+
+                if (strcmp(q, "digital_signature") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_DIGITAL_SIGNATURE;
+                } else if (strcmp(q, "non_repudiation") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_NON_REPUDIATION;
+                } else if (strcmp(q, "key_encipherment") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_ENCIPHERMENT;
+                } else if (strcmp(q, "data_encipherment") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_DATA_ENCIPHERMENT;
+                } else if (strcmp(q, "key_agreement") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_AGREEMENT;
+                } else if (strcmp(q, "key_cert_sign") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_CERT_SIGN;
+                } else if (strcmp(q, "crl_sign") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_CRL_SIGN;
+                } else {
+                    goto usage;
+                }
+
+                q = r;
+            }
+        } else if (strcmp(p, "force_key_usage") == 0) {
+            switch (atoi(q)) {
+                case 0: opt.force_key_usage = 0; break;
+                case 1: opt.force_key_usage = 1; break;
+                default: goto usage;
+            }
+        } else if (strcmp(p, "ns_cert_type") == 0) {
+            while (q != NULL) {
+                if ((r = strchr(q, ',')) != NULL) {
+                    *r++ = '\0';
+                }
+
+                if (strcmp(q, "ssl_client") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT;
+                } else if (strcmp(q, "ssl_server") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER;
+                } else if (strcmp(q, "email") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_EMAIL;
+                } else if (strcmp(q, "object_signing") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_OBJECT_SIGNING;
+                } else if (strcmp(q, "ssl_ca") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_CA;
+                } else if (strcmp(q, "email_ca") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_EMAIL_CA;
+                } else if (strcmp(q, "object_signing_ca") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_OBJECT_SIGNING_CA;
+                } else {
+                    goto usage;
+                }
+
+                q = r;
+            }
+        } else if (strcmp(p, "force_ns_cert_type") == 0) {
+            switch (atoi(q)) {
+                case 0: opt.force_ns_cert_type = 0; break;
+                case 1: opt.force_ns_cert_type = 1; break;
+                default: goto usage;
+            }
+        } else {
+            goto usage;
+        }
+    }
+
+    /* Set the MD algorithm to use for the signature in the CSR */
+    mbedtls_x509write_csr_set_md_alg(&req, opt.md_alg);
+
+    /* Set the Key Usage Extension flags in the CSR */
+    if (opt.key_usage || opt.force_key_usage == 1) {
+        ret = mbedtls_x509write_csr_set_key_usage(&req, opt.key_usage);
+
+        if (ret != 0) {
+            mbedtls_printf(" failed\n  !  mbedtls_x509write_csr_set_key_usage returned %d", ret);
+            goto exit;
+        }
+    }
+
+    /* Set the Cert Type flags in the CSR */
+    if (opt.ns_cert_type || opt.force_ns_cert_type == 1) {
+        ret = mbedtls_x509write_csr_set_ns_cert_type(&req, opt.ns_cert_type);
+
+        if (ret != 0) {
+            mbedtls_printf(" failed\n  !  mbedtls_x509write_csr_set_ns_cert_type returned %d", ret);
+            goto exit;
+        }
+    }
+
+    /* Set the SubjectAltName in the CSR */
+    if (opt.san_list != NULL) {
+        ret = mbedtls_x509write_csr_set_subject_alternative_name(&req, opt.san_list);
+
+        if (ret != 0) {
+            mbedtls_printf(
+                " failed\n  !  mbedtls_x509write_csr_set_subject_alternative_name returned %d",
+                ret);
+            goto exit;
+        }
+    }
+
+    /*
+     * 0. Seed the PRNG
+     */
+    mbedtls_printf("  . Seeding the random number generator...");
+    fflush(stdout);
+
+    if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
+                                     (const unsigned char *) pers,
+                                     strlen(pers))) != 0) {
+        mbedtls_printf(" failed\n  !  mbedtls_ctr_drbg_seed returned %d", ret);
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    /*
+     * 1.0. Check the subject name for validity
+     */
+    mbedtls_printf("  . Checking subject name...");
+    fflush(stdout);
+
+    if ((ret = mbedtls_x509write_csr_set_subject_name(&req, opt.subject_name)) != 0) {
+        mbedtls_printf(" failed\n  !  mbedtls_x509write_csr_set_subject_name returned %d", ret);
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    /*
+     * 1.1. Load the key
+     */
+    mbedtls_printf("  . Loading the private key ...");
+    fflush(stdout);
+
+    ret = mbedtls_pk_parse_keyfile(&key, opt.filename, opt.password,
+                                   mbedtls_ctr_drbg_random, &ctr_drbg);
+
+    if (ret != 0) {
+        mbedtls_printf(" failed\n  !  mbedtls_pk_parse_keyfile returned %d", ret);
+        goto exit;
+    }
+
+    mbedtls_x509write_csr_set_key(&req, &key);
+
+    mbedtls_printf(" ok\n");
+
+    /*
+     * 1.2. Writing the request
+     */
+    mbedtls_printf("  . Writing the certificate request ...");
+    fflush(stdout);
+
+    if ((ret = write_certificate_request(&req, opt.output_file,
+                                         mbedtls_ctr_drbg_random, &ctr_drbg)) != 0) {
+        mbedtls_printf(" failed\n  !  write_certificate_request %d", ret);
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    exit_code = MBEDTLS_EXIT_SUCCESS;
+
+exit:
+
+    if (exit_code != MBEDTLS_EXIT_SUCCESS) {
+#ifdef MBEDTLS_ERROR_C
+        mbedtls_strerror(ret, buf, sizeof(buf));
+        mbedtls_printf(" - %s\n", buf);
+#else
+        mbedtls_printf("\n");
+#endif
+    }
+
+    mbedtls_x509write_csr_free(&req);
+    mbedtls_asn1_free_named_data_list(&ext_san_dirname);
+    mbedtls_pk_free(&key);
+    mbedtls_ctr_drbg_free(&ctr_drbg);
+    mbedtls_entropy_free(&entropy);
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_psa_crypto_free();
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    cur = opt.san_list;
+    while (cur != NULL) {
+        prev = cur;
+        cur = cur->next;
+        mbedtls_free(prev);
+    }
+
+
+    mbedtls_exit(exit_code);
+}
+#endif /* MBEDTLS_X509_CSR_WRITE_C && MBEDTLS_PK_PARSE_C && MBEDTLS_FS_IO &&
+          MBEDTLS_ENTROPY_C && MBEDTLS_CTR_DRBG_C && MBEDTLS_PEM_WRITE_C */
diff --git a/programs/x509/cert_write.c b/programs/x509/cert_write.c
new file mode 100644
index 0000000..0b2575e
--- /dev/null
+++ b/programs/x509/cert_write.c
@@ -0,0 +1,1016 @@
+/*
+ *  Certificate generation and signing
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include "mbedtls/build_info.h"
+
+#include "mbedtls/platform.h"
+/* md.h is included this early since MD_CAN_XXX macros are defined there. */
+#include "mbedtls/md.h"
+
+#if !defined(MBEDTLS_X509_CRT_WRITE_C) || \
+    !defined(MBEDTLS_X509_CRT_PARSE_C) || !defined(MBEDTLS_FS_IO) || \
+    !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C) || \
+    !defined(MBEDTLS_ERROR_C) || !defined(MBEDTLS_MD_CAN_SHA256) || \
+    !defined(MBEDTLS_PEM_WRITE_C) || !defined(MBEDTLS_MD_C)
+int main(void)
+{
+    mbedtls_printf("MBEDTLS_X509_CRT_WRITE_C and/or MBEDTLS_X509_CRT_PARSE_C and/or "
+                   "MBEDTLS_FS_IO and/or MBEDTLS_MD_CAN_SHA256 and/or "
+                   "MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C and/or "
+                   "MBEDTLS_ERROR_C not defined.\n");
+    mbedtls_exit(0);
+}
+#else
+
+#include "mbedtls/x509_crt.h"
+#include "mbedtls/x509_csr.h"
+#include "mbedtls/oid.h"
+#include "mbedtls/entropy.h"
+#include "mbedtls/ctr_drbg.h"
+#include "mbedtls/error.h"
+#include "test/helpers.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#define SET_OID(x, oid) \
+    do { x.len = MBEDTLS_OID_SIZE(oid); x.p = (unsigned char *) oid; } while (0)
+
+#if defined(MBEDTLS_X509_CSR_PARSE_C)
+#define USAGE_CSR                                                           \
+    "    request_file=%%s         default: (empty)\n"                           \
+    "                            If request_file is specified, subject_key,\n"  \
+    "                            subject_pwd and subject_name are ignored!\n"
+#else
+#define USAGE_CSR ""
+#endif /* MBEDTLS_X509_CSR_PARSE_C */
+
+#define FORMAT_PEM              0
+#define FORMAT_DER              1
+
+#define DFL_ISSUER_CRT          ""
+#define DFL_REQUEST_FILE        ""
+#define DFL_SUBJECT_KEY         "subject.key"
+#define DFL_ISSUER_KEY          "ca.key"
+#define DFL_SUBJECT_PWD         ""
+#define DFL_ISSUER_PWD          ""
+#define DFL_OUTPUT_FILENAME     "cert.crt"
+#define DFL_SUBJECT_NAME        "CN=Cert,O=mbed TLS,C=UK"
+#define DFL_ISSUER_NAME         "CN=CA,O=mbed TLS,C=UK"
+#define DFL_NOT_BEFORE          "20010101000000"
+#define DFL_NOT_AFTER           "20301231235959"
+#define DFL_SERIAL              "1"
+#define DFL_SERIAL_HEX          "1"
+#define DFL_EXT_SUBJECTALTNAME  ""
+#define DFL_SELFSIGN            0
+#define DFL_IS_CA               0
+#define DFL_MAX_PATHLEN         -1
+#define DFL_SIG_ALG             MBEDTLS_MD_SHA256
+#define DFL_KEY_USAGE           0
+#define DFL_EXT_KEY_USAGE       NULL
+#define DFL_NS_CERT_TYPE        0
+#define DFL_VERSION             3
+#define DFL_AUTH_IDENT          1
+#define DFL_SUBJ_IDENT          1
+#define DFL_CONSTRAINTS         1
+#define DFL_DIGEST              MBEDTLS_MD_SHA256
+#define DFL_FORMAT              FORMAT_PEM
+
+#define USAGE \
+    "\n usage: cert_write param=<>...\n"                \
+    "\n acceptable parameters:\n"                       \
+    USAGE_CSR                                           \
+    "    subject_key=%%s          default: subject.key\n"   \
+    "    subject_pwd=%%s          default: (empty)\n"       \
+    "    subject_name=%%s         default: CN=Cert,O=mbed TLS,C=UK\n"   \
+    "\n"                                                \
+    "    issuer_crt=%%s           default: (empty)\n"       \
+    "                            If issuer_crt is specified, issuer_name is\n"  \
+    "                            ignored!\n"                \
+    "    issuer_name=%%s          default: CN=CA,O=mbed TLS,C=UK\n"     \
+    "\n"                                                \
+    "    selfsign=%%d             default: 0 (false)\n"     \
+    "                            If selfsign is enabled, issuer_name and\n" \
+    "                            issuer_key are required (issuer_crt and\n" \
+    "                            subject_* are ignored\n"   \
+    "    issuer_key=%%s           default: ca.key\n"        \
+    "    issuer_pwd=%%s           default: (empty)\n"       \
+    "    output_file=%%s          default: cert.crt\n"      \
+    "    serial=%%s               default: 1\n"             \
+    "                            In decimal format; it can be used as\n"     \
+    "                            alternative to serial_hex, but it's\n"      \
+    "                            limited in max length to\n"                 \
+    "                            unsigned long long int\n"                   \
+    "    serial_hex=%%s           default: 1\n"             \
+    "                            In hex format; it can be used as\n"         \
+    "                            alternative to serial\n"                    \
+    "    not_before=%%s           default: 20010101000000\n" \
+    "    not_after=%%s            default: 20301231235959\n" \
+    "    is_ca=%%d                default: 0 (disabled)\n"  \
+    "    max_pathlen=%%d          default: -1 (none)\n"     \
+    "    md=%%s                   default: SHA256\n"        \
+    "                            Supported values (if enabled):\n"      \
+    "                            MD5, RIPEMD160, SHA1,\n" \
+    "                            SHA224, SHA256, SHA384, SHA512\n" \
+    "    version=%%d              default: 3\n"            \
+    "                            Possible values: 1, 2, 3\n" \
+    "    subject_identifier=%%s   default: 1\n"             \
+    "                            Possible values: 0, 1\n"   \
+    "                            (Considered for v3 only)\n" \
+    "    san=%%s                   default: (none)\n"       \
+    "                            Semicolon-separated-list of values:\n" \
+    "                             DNS:value\n"            \
+    "                             URI:value\n"            \
+    "                             RFC822:value\n"         \
+    "                             IP:value (Only IPv4 is supported)\n" \
+    "                             DN:list of comma separated key=value pairs\n" \
+    "    authority_identifier=%%s default: 1\n"             \
+    "                            Possible values: 0, 1\n"   \
+    "                            (Considered for v3 only)\n" \
+    "    basic_constraints=%%d    default: 1\n"             \
+    "                            Possible values: 0, 1\n"   \
+    "                            (Considered for v3 only)\n" \
+    "    key_usage=%%s            default: (empty)\n"       \
+    "                            Comma-separated-list of values:\n"     \
+    "                            digital_signature\n"     \
+    "                            non_repudiation\n"       \
+    "                            key_encipherment\n"      \
+    "                            data_encipherment\n"     \
+    "                            key_agreement\n"         \
+    "                            key_cert_sign\n"  \
+    "                            crl_sign\n"              \
+    "                            (Considered for v3 only)\n" \
+    "    ext_key_usage=%%s        default: (empty)\n"      \
+    "                            Comma-separated-list of values:\n"     \
+    "                            serverAuth\n"             \
+    "                            clientAuth\n"             \
+    "                            codeSigning\n"            \
+    "                            emailProtection\n"        \
+    "                            timeStamping\n"           \
+    "                            OCSPSigning\n"            \
+    "    ns_cert_type=%%s         default: (empty)\n"       \
+    "                            Comma-separated-list of values:\n"     \
+    "                            ssl_client\n"            \
+    "                            ssl_server\n"            \
+    "                            email\n"                 \
+    "                            object_signing\n"        \
+    "                            ssl_ca\n"                \
+    "                            email_ca\n"              \
+    "                            object_signing_ca\n"     \
+    "   format=pem|der           default: pem\n"         \
+    "\n"
+
+typedef enum {
+    SERIAL_FRMT_UNSPEC,
+    SERIAL_FRMT_DEC,
+    SERIAL_FRMT_HEX
+} serial_format_t;
+
+/*
+ * global options
+ */
+struct options {
+    const char *issuer_crt;     /* filename of the issuer certificate   */
+    const char *request_file;   /* filename of the certificate request  */
+    const char *subject_key;    /* filename of the subject key file     */
+    const char *issuer_key;     /* filename of the issuer key file      */
+    const char *subject_pwd;    /* password for the subject key file    */
+    const char *issuer_pwd;     /* password for the issuer key file     */
+    const char *output_file;    /* where to store the constructed CRT   */
+    const char *subject_name;   /* subject name for certificate         */
+    mbedtls_x509_san_list *san_list; /* subjectAltName for certificate  */
+    const char *issuer_name;    /* issuer name for certificate          */
+    const char *not_before;     /* validity period not before           */
+    const char *not_after;      /* validity period not after            */
+    const char *serial;         /* serial number string (decimal)       */
+    const char *serial_hex;     /* serial number string (hex)           */
+    int selfsign;               /* selfsign the certificate             */
+    int is_ca;                  /* is a CA certificate                  */
+    int max_pathlen;            /* maximum CA path length               */
+    int authority_identifier;   /* add authority identifier to CRT      */
+    int subject_identifier;     /* add subject identifier to CRT        */
+    int basic_constraints;      /* add basic constraints ext to CRT     */
+    int version;                /* CRT version                          */
+    mbedtls_md_type_t md;       /* Hash used for signing                */
+    unsigned char key_usage;    /* key usage flags                      */
+    mbedtls_asn1_sequence *ext_key_usage; /* extended key usages        */
+    unsigned char ns_cert_type; /* NS cert type                         */
+    int format;                 /* format                               */
+} opt;
+
+int write_certificate(mbedtls_x509write_cert *crt, const char *output_file,
+                      int (*f_rng)(void *, unsigned char *, size_t),
+                      void *p_rng)
+{
+    int ret;
+    FILE *f;
+    unsigned char output_buf[4096];
+    unsigned char *output_start;
+    size_t len = 0;
+
+    memset(output_buf, 0, 4096);
+    if (opt.format == FORMAT_DER) {
+        ret = mbedtls_x509write_crt_der(crt, output_buf, 4096,
+                                        f_rng, p_rng);
+        if (ret < 0) {
+            return ret;
+        }
+
+        len = ret;
+        output_start = output_buf + 4096 - len;
+    } else {
+        ret = mbedtls_x509write_crt_pem(crt, output_buf, 4096,
+                                        f_rng, p_rng);
+        if (ret < 0) {
+            return ret;
+        }
+
+        len = strlen((char *) output_buf);
+        output_start = output_buf;
+    }
+
+    if ((f = fopen(output_file, "w")) == NULL) {
+        return -1;
+    }
+
+    if (fwrite(output_start, 1, len, f) != len) {
+        fclose(f);
+        return -1;
+    }
+
+    fclose(f);
+
+    return 0;
+}
+
+int parse_serial_decimal_format(unsigned char *obuf, size_t obufmax,
+                                const char *ibuf, size_t *len)
+{
+    unsigned long long int dec;
+    unsigned int remaining_bytes = sizeof(dec);
+    unsigned char *p = obuf;
+    unsigned char val;
+    char *end_ptr = NULL;
+
+    errno = 0;
+    dec = strtoull(ibuf, &end_ptr, 10);
+
+    if ((errno != 0) || (end_ptr == ibuf)) {
+        return -1;
+    }
+
+    *len = 0;
+
+    while (remaining_bytes > 0) {
+        if (obufmax < (*len + 1)) {
+            return -1;
+        }
+
+        val = (dec >> ((remaining_bytes - 1) * 8)) & 0xFF;
+
+        /* Skip leading zeros */
+        if ((val != 0) || (*len != 0)) {
+            *p = val;
+            (*len)++;
+            p++;
+        }
+
+        remaining_bytes--;
+    }
+
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    int ret = 1;
+    int exit_code = MBEDTLS_EXIT_FAILURE;
+    mbedtls_x509_crt issuer_crt;
+    mbedtls_pk_context loaded_issuer_key, loaded_subject_key;
+    mbedtls_pk_context *issuer_key = &loaded_issuer_key,
+                       *subject_key = &loaded_subject_key;
+    char buf[1024];
+    char issuer_name[256];
+    int i;
+    char *p, *q, *r;
+#if defined(MBEDTLS_X509_CSR_PARSE_C)
+    char subject_name[256];
+    mbedtls_x509_csr csr;
+#endif
+    mbedtls_x509write_cert crt;
+    serial_format_t serial_frmt = SERIAL_FRMT_UNSPEC;
+    unsigned char serial[MBEDTLS_X509_RFC5280_MAX_SERIAL_LEN];
+    size_t serial_len;
+    mbedtls_asn1_sequence *ext_key_usage;
+    mbedtls_entropy_context entropy;
+    mbedtls_ctr_drbg_context ctr_drbg;
+    const char *pers = "crt example app";
+    mbedtls_x509_san_list *cur, *prev;
+    mbedtls_asn1_named_data *ext_san_dirname = NULL;
+    uint8_t ip[4] = { 0 };
+    /*
+     * Set to sane values
+     */
+    mbedtls_x509write_crt_init(&crt);
+    mbedtls_pk_init(&loaded_issuer_key);
+    mbedtls_pk_init(&loaded_subject_key);
+    mbedtls_ctr_drbg_init(&ctr_drbg);
+    mbedtls_entropy_init(&entropy);
+#if defined(MBEDTLS_X509_CSR_PARSE_C)
+    mbedtls_x509_csr_init(&csr);
+#endif
+    mbedtls_x509_crt_init(&issuer_crt);
+    memset(buf, 0, sizeof(buf));
+    memset(serial, 0, sizeof(serial));
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_status_t status = psa_crypto_init();
+    if (status != PSA_SUCCESS) {
+        mbedtls_fprintf(stderr, "Failed to initialize PSA Crypto implementation: %d\n",
+                        (int) status);
+        goto exit;
+    }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    if (argc < 2) {
+usage:
+        mbedtls_printf(USAGE);
+        goto exit;
+    }
+
+    opt.issuer_crt          = DFL_ISSUER_CRT;
+    opt.request_file        = DFL_REQUEST_FILE;
+    opt.subject_key         = DFL_SUBJECT_KEY;
+    opt.issuer_key          = DFL_ISSUER_KEY;
+    opt.subject_pwd         = DFL_SUBJECT_PWD;
+    opt.issuer_pwd          = DFL_ISSUER_PWD;
+    opt.output_file         = DFL_OUTPUT_FILENAME;
+    opt.subject_name        = DFL_SUBJECT_NAME;
+    opt.issuer_name         = DFL_ISSUER_NAME;
+    opt.not_before          = DFL_NOT_BEFORE;
+    opt.not_after           = DFL_NOT_AFTER;
+    opt.serial              = DFL_SERIAL;
+    opt.serial_hex          = DFL_SERIAL_HEX;
+    opt.selfsign            = DFL_SELFSIGN;
+    opt.is_ca               = DFL_IS_CA;
+    opt.max_pathlen         = DFL_MAX_PATHLEN;
+    opt.key_usage           = DFL_KEY_USAGE;
+    opt.ext_key_usage       = DFL_EXT_KEY_USAGE;
+    opt.ns_cert_type        = DFL_NS_CERT_TYPE;
+    opt.version             = DFL_VERSION - 1;
+    opt.md                  = DFL_DIGEST;
+    opt.subject_identifier   = DFL_SUBJ_IDENT;
+    opt.authority_identifier = DFL_AUTH_IDENT;
+    opt.basic_constraints    = DFL_CONSTRAINTS;
+    opt.format              = DFL_FORMAT;
+    opt.san_list            = NULL;
+
+    for (i = 1; i < argc; i++) {
+
+        p = argv[i];
+        if ((q = strchr(p, '=')) == NULL) {
+            goto usage;
+        }
+        *q++ = '\0';
+
+        if (strcmp(p, "request_file") == 0) {
+            opt.request_file = q;
+        } else if (strcmp(p, "subject_key") == 0) {
+            opt.subject_key = q;
+        } else if (strcmp(p, "issuer_key") == 0) {
+            opt.issuer_key = q;
+        } else if (strcmp(p, "subject_pwd") == 0) {
+            opt.subject_pwd = q;
+        } else if (strcmp(p, "issuer_pwd") == 0) {
+            opt.issuer_pwd = q;
+        } else if (strcmp(p, "issuer_crt") == 0) {
+            opt.issuer_crt = q;
+        } else if (strcmp(p, "output_file") == 0) {
+            opt.output_file = q;
+        } else if (strcmp(p, "subject_name") == 0) {
+            opt.subject_name = q;
+        } else if (strcmp(p, "issuer_name") == 0) {
+            opt.issuer_name = q;
+        } else if (strcmp(p, "not_before") == 0) {
+            opt.not_before = q;
+        } else if (strcmp(p, "not_after") == 0) {
+            opt.not_after = q;
+        } else if (strcmp(p, "serial") == 0) {
+            if (serial_frmt != SERIAL_FRMT_UNSPEC) {
+                mbedtls_printf("Invalid attempt to set the serial more than once\n");
+                goto usage;
+            }
+            serial_frmt = SERIAL_FRMT_DEC;
+            opt.serial = q;
+        } else if (strcmp(p, "serial_hex") == 0) {
+            if (serial_frmt != SERIAL_FRMT_UNSPEC) {
+                mbedtls_printf("Invalid attempt to set the serial more than once\n");
+                goto usage;
+            }
+            serial_frmt = SERIAL_FRMT_HEX;
+            opt.serial_hex = q;
+        } else if (strcmp(p, "authority_identifier") == 0) {
+            opt.authority_identifier = atoi(q);
+            if (opt.authority_identifier != 0 &&
+                opt.authority_identifier != 1) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+        } else if (strcmp(p, "subject_identifier") == 0) {
+            opt.subject_identifier = atoi(q);
+            if (opt.subject_identifier != 0 &&
+                opt.subject_identifier != 1) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+        } else if (strcmp(p, "basic_constraints") == 0) {
+            opt.basic_constraints = atoi(q);
+            if (opt.basic_constraints != 0 &&
+                opt.basic_constraints != 1) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+        } else if (strcmp(p, "md") == 0) {
+            const mbedtls_md_info_t *md_info =
+                mbedtls_md_info_from_string(q);
+            if (md_info == NULL) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+            opt.md = mbedtls_md_get_type(md_info);
+        } else if (strcmp(p, "version") == 0) {
+            opt.version = atoi(q);
+            if (opt.version < 1 || opt.version > 3) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+            opt.version--;
+        } else if (strcmp(p, "selfsign") == 0) {
+            opt.selfsign = atoi(q);
+            if (opt.selfsign < 0 || opt.selfsign > 1) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+        } else if (strcmp(p, "is_ca") == 0) {
+            opt.is_ca = atoi(q);
+            if (opt.is_ca < 0 || opt.is_ca > 1) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+        } else if (strcmp(p, "max_pathlen") == 0) {
+            opt.max_pathlen = atoi(q);
+            if (opt.max_pathlen < -1 || opt.max_pathlen > 127) {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+        } else if (strcmp(p, "key_usage") == 0) {
+            while (q != NULL) {
+                if ((r = strchr(q, ',')) != NULL) {
+                    *r++ = '\0';
+                }
+
+                if (strcmp(q, "digital_signature") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_DIGITAL_SIGNATURE;
+                } else if (strcmp(q, "non_repudiation") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_NON_REPUDIATION;
+                } else if (strcmp(q, "key_encipherment") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_ENCIPHERMENT;
+                } else if (strcmp(q, "data_encipherment") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_DATA_ENCIPHERMENT;
+                } else if (strcmp(q, "key_agreement") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_AGREEMENT;
+                } else if (strcmp(q, "key_cert_sign") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_CERT_SIGN;
+                } else if (strcmp(q, "crl_sign") == 0) {
+                    opt.key_usage |= MBEDTLS_X509_KU_CRL_SIGN;
+                } else {
+                    mbedtls_printf("Invalid argument for option %s\n", p);
+                    goto usage;
+                }
+
+                q = r;
+            }
+        } else if (strcmp(p, "ext_key_usage") == 0) {
+            mbedtls_asn1_sequence **tail = &opt.ext_key_usage;
+
+            while (q != NULL) {
+                if ((r = strchr(q, ',')) != NULL) {
+                    *r++ = '\0';
+                }
+
+                ext_key_usage = mbedtls_calloc(1, sizeof(mbedtls_asn1_sequence));
+                ext_key_usage->buf.tag = MBEDTLS_ASN1_OID;
+                if (strcmp(q, "serverAuth") == 0) {
+                    SET_OID(ext_key_usage->buf, MBEDTLS_OID_SERVER_AUTH);
+                } else if (strcmp(q, "clientAuth") == 0) {
+                    SET_OID(ext_key_usage->buf, MBEDTLS_OID_CLIENT_AUTH);
+                } else if (strcmp(q, "codeSigning") == 0) {
+                    SET_OID(ext_key_usage->buf, MBEDTLS_OID_CODE_SIGNING);
+                } else if (strcmp(q, "emailProtection") == 0) {
+                    SET_OID(ext_key_usage->buf, MBEDTLS_OID_EMAIL_PROTECTION);
+                } else if (strcmp(q, "timeStamping") == 0) {
+                    SET_OID(ext_key_usage->buf, MBEDTLS_OID_TIME_STAMPING);
+                } else if (strcmp(q, "OCSPSigning") == 0) {
+                    SET_OID(ext_key_usage->buf, MBEDTLS_OID_OCSP_SIGNING);
+                } else if (strcmp(q, "any") == 0) {
+                    SET_OID(ext_key_usage->buf, MBEDTLS_OID_ANY_EXTENDED_KEY_USAGE);
+                } else {
+                    mbedtls_printf("Invalid argument for option %s\n", p);
+                    goto usage;
+                }
+
+                *tail = ext_key_usage;
+                tail = &ext_key_usage->next;
+
+                q = r;
+            }
+        } else if (strcmp(p, "san") == 0) {
+            char *subtype_value;
+            prev = NULL;
+
+            while (q != NULL) {
+                char *semicolon;
+                r = q;
+
+                /* Find the first non-escaped ; occurrence and remove escaped ones */
+                do {
+                    if ((semicolon = strchr(r, ';')) != NULL) {
+                        if (*(semicolon-1) != '\\') {
+                            r = semicolon;
+                            break;
+                        }
+                        /* Remove the escape character */
+                        size_t size_left = strlen(semicolon);
+                        memmove(semicolon-1, semicolon, size_left);
+                        *(semicolon + size_left - 1) = '\0';
+                        /* r will now point at the character after the semicolon */
+                        r = semicolon;
+                    }
+
+                } while (semicolon != NULL);
+
+                if (semicolon != NULL) {
+                    *r++ = '\0';
+                } else {
+                    r = NULL;
+                }
+
+                cur = mbedtls_calloc(1, sizeof(mbedtls_x509_san_list));
+                if (cur == NULL) {
+                    mbedtls_printf("Not enough memory for subjectAltName list\n");
+                    goto usage;
+                }
+
+                cur->next = NULL;
+
+                if ((subtype_value = strchr(q, ':')) != NULL) {
+                    *subtype_value++ = '\0';
+                } else {
+                    mbedtls_printf(
+                        "Invalid argument for option SAN: Entry must be of the form TYPE:value\n");
+                    goto usage;
+                }
+                if (strcmp(q, "RFC822") == 0) {
+                    cur->node.type = MBEDTLS_X509_SAN_RFC822_NAME;
+                } else if (strcmp(q, "URI") == 0) {
+                    cur->node.type = MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER;
+                } else if (strcmp(q, "DNS") == 0) {
+                    cur->node.type = MBEDTLS_X509_SAN_DNS_NAME;
+                } else if (strcmp(q, "IP") == 0) {
+                    size_t ip_addr_len = 0;
+                    cur->node.type = MBEDTLS_X509_SAN_IP_ADDRESS;
+                    ip_addr_len = mbedtls_x509_crt_parse_cn_inet_pton(subtype_value, ip);
+                    if (ip_addr_len == 0) {
+                        mbedtls_printf("mbedtls_x509_crt_parse_cn_inet_pton failed to parse %s\n",
+                                       subtype_value);
+                        goto exit;
+                    }
+                    cur->node.san.unstructured_name.p = (unsigned char *) ip;
+                    cur->node.san.unstructured_name.len = sizeof(ip);
+                } else if (strcmp(q, "DN") == 0) {
+                    cur->node.type = MBEDTLS_X509_SAN_DIRECTORY_NAME;
+                    if ((ret = mbedtls_x509_string_to_names(&ext_san_dirname,
+                                                            subtype_value)) != 0) {
+                        mbedtls_strerror(ret, buf, sizeof(buf));
+                        mbedtls_printf(
+                            " failed\n  !  mbedtls_x509_string_to_names "
+                            "returned -0x%04x - %s\n\n",
+                            (unsigned int) -ret, buf);
+                        goto exit;
+                    }
+                    cur->node.san.directory_name = *ext_san_dirname;
+                } else {
+                    mbedtls_free(cur);
+                    goto usage;
+                }
+
+                if (cur->node.type == MBEDTLS_X509_SAN_RFC822_NAME ||
+                    cur->node.type == MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER ||
+                    cur->node.type == MBEDTLS_X509_SAN_DNS_NAME) {
+                    q = subtype_value;
+                    cur->node.san.unstructured_name.p = (unsigned char *) q;
+                    cur->node.san.unstructured_name.len = strlen(q);
+                }
+
+                if (prev == NULL) {
+                    opt.san_list = cur;
+                } else {
+                    prev->next = cur;
+                }
+
+                prev = cur;
+                q = r;
+            }
+        } else if (strcmp(p, "ns_cert_type") == 0) {
+            while (q != NULL) {
+                if ((r = strchr(q, ',')) != NULL) {
+                    *r++ = '\0';
+                }
+
+                if (strcmp(q, "ssl_client") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT;
+                } else if (strcmp(q, "ssl_server") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER;
+                } else if (strcmp(q, "email") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_EMAIL;
+                } else if (strcmp(q, "object_signing") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_OBJECT_SIGNING;
+                } else if (strcmp(q, "ssl_ca") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_CA;
+                } else if (strcmp(q, "email_ca") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_EMAIL_CA;
+                } else if (strcmp(q, "object_signing_ca") == 0) {
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_OBJECT_SIGNING_CA;
+                } else {
+                    mbedtls_printf("Invalid argument for option %s\n", p);
+                    goto usage;
+                }
+
+                q = r;
+            }
+        } else if (strcmp(p, "format") == 0) {
+            if (strcmp(q, "der") == 0) {
+                opt.format = FORMAT_DER;
+            } else if (strcmp(q, "pem") == 0) {
+                opt.format = FORMAT_PEM;
+            } else {
+                mbedtls_printf("Invalid argument for option %s\n", p);
+                goto usage;
+            }
+        } else {
+            goto usage;
+        }
+    }
+
+    mbedtls_printf("\n");
+
+    /*
+     * 0. Seed the PRNG
+     */
+    mbedtls_printf("  . Seeding the random number generator...");
+    fflush(stdout);
+
+    if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
+                                     (const unsigned char *) pers,
+                                     strlen(pers))) != 0) {
+        mbedtls_strerror(ret, buf, sizeof(buf));
+        mbedtls_printf(" failed\n  !  mbedtls_ctr_drbg_seed returned %d - %s\n",
+                       ret, buf);
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    // Parse serial to MPI
+    //
+    mbedtls_printf("  . Reading serial number...");
+    fflush(stdout);
+
+    if (serial_frmt == SERIAL_FRMT_HEX) {
+        ret = mbedtls_test_unhexify(serial, sizeof(serial),
+                                    opt.serial_hex, &serial_len);
+    } else { // SERIAL_FRMT_DEC || SERIAL_FRMT_UNSPEC
+        ret = parse_serial_decimal_format(serial, sizeof(serial),
+                                          opt.serial, &serial_len);
+    }
+
+    if (ret != 0) {
+        mbedtls_printf(" failed\n  !  Unable to parse serial\n");
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    // Parse issuer certificate if present
+    //
+    if (!opt.selfsign && strlen(opt.issuer_crt)) {
+        /*
+         * 1.0.a. Load the certificates
+         */
+        mbedtls_printf("  . Loading the issuer certificate ...");
+        fflush(stdout);
+
+        if ((ret = mbedtls_x509_crt_parse_file(&issuer_crt, opt.issuer_crt)) != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_x509_crt_parse_file "
+                           "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        ret = mbedtls_x509_dn_gets(issuer_name, sizeof(issuer_name),
+                                   &issuer_crt.subject);
+        if (ret < 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_x509_dn_gets "
+                           "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        opt.issuer_name = issuer_name;
+
+        mbedtls_printf(" ok\n");
+    }
+
+#if defined(MBEDTLS_X509_CSR_PARSE_C)
+    // Parse certificate request if present
+    //
+    if (!opt.selfsign && strlen(opt.request_file)) {
+        /*
+         * 1.0.b. Load the CSR
+         */
+        mbedtls_printf("  . Loading the certificate request ...");
+        fflush(stdout);
+
+        if ((ret = mbedtls_x509_csr_parse_file(&csr, opt.request_file)) != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_x509_csr_parse_file "
+                           "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        ret = mbedtls_x509_dn_gets(subject_name, sizeof(subject_name),
+                                   &csr.subject);
+        if (ret < 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_x509_dn_gets "
+                           "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        opt.subject_name = subject_name;
+        subject_key = &csr.pk;
+
+        mbedtls_printf(" ok\n");
+    }
+#endif /* MBEDTLS_X509_CSR_PARSE_C */
+
+    /*
+     * 1.1. Load the keys
+     */
+    if (!opt.selfsign && !strlen(opt.request_file)) {
+        mbedtls_printf("  . Loading the subject key ...");
+        fflush(stdout);
+
+        ret = mbedtls_pk_parse_keyfile(&loaded_subject_key, opt.subject_key,
+                                       opt.subject_pwd, mbedtls_ctr_drbg_random, &ctr_drbg);
+        if (ret != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_pk_parse_keyfile "
+                           "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        mbedtls_printf(" ok\n");
+    }
+
+    mbedtls_printf("  . Loading the issuer key ...");
+    fflush(stdout);
+
+    ret = mbedtls_pk_parse_keyfile(&loaded_issuer_key, opt.issuer_key,
+                                   opt.issuer_pwd, mbedtls_ctr_drbg_random, &ctr_drbg);
+    if (ret != 0) {
+        mbedtls_strerror(ret, buf, sizeof(buf));
+        mbedtls_printf(" failed\n  !  mbedtls_pk_parse_keyfile "
+                       "returned -x%02x - %s\n\n", (unsigned int) -ret, buf);
+        goto exit;
+    }
+
+    // Check if key and issuer certificate match
+    //
+    if (strlen(opt.issuer_crt)) {
+        if (mbedtls_pk_check_pair(&issuer_crt.pk, issuer_key,
+                                  mbedtls_ctr_drbg_random, &ctr_drbg) != 0) {
+            mbedtls_printf(" failed\n  !  issuer_key does not match "
+                           "issuer certificate\n\n");
+            goto exit;
+        }
+    }
+
+    mbedtls_printf(" ok\n");
+
+    if (opt.selfsign) {
+        opt.subject_name = opt.issuer_name;
+        subject_key = issuer_key;
+    }
+
+    mbedtls_x509write_crt_set_subject_key(&crt, subject_key);
+    mbedtls_x509write_crt_set_issuer_key(&crt, issuer_key);
+
+    /*
+     * 1.0. Check the names for validity
+     */
+    if ((ret = mbedtls_x509write_crt_set_subject_name(&crt, opt.subject_name)) != 0) {
+        mbedtls_strerror(ret, buf, sizeof(buf));
+        mbedtls_printf(" failed\n  !  mbedtls_x509write_crt_set_subject_name "
+                       "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+        goto exit;
+    }
+
+    if ((ret = mbedtls_x509write_crt_set_issuer_name(&crt, opt.issuer_name)) != 0) {
+        mbedtls_strerror(ret, buf, sizeof(buf));
+        mbedtls_printf(" failed\n  !  mbedtls_x509write_crt_set_issuer_name "
+                       "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+        goto exit;
+    }
+
+    mbedtls_printf("  . Setting certificate values ...");
+    fflush(stdout);
+
+    mbedtls_x509write_crt_set_version(&crt, opt.version);
+    mbedtls_x509write_crt_set_md_alg(&crt, opt.md);
+
+    ret = mbedtls_x509write_crt_set_serial_raw(&crt, serial, serial_len);
+    if (ret != 0) {
+        mbedtls_strerror(ret, buf, sizeof(buf));
+        mbedtls_printf(" failed\n  !  mbedtls_x509write_crt_set_serial_raw "
+                       "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+        goto exit;
+    }
+
+    ret = mbedtls_x509write_crt_set_validity(&crt, opt.not_before, opt.not_after);
+    if (ret != 0) {
+        mbedtls_strerror(ret, buf, sizeof(buf));
+        mbedtls_printf(" failed\n  !  mbedtls_x509write_crt_set_validity "
+                       "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    if (opt.version == MBEDTLS_X509_CRT_VERSION_3 &&
+        opt.basic_constraints != 0) {
+        mbedtls_printf("  . Adding the Basic Constraints extension ...");
+        fflush(stdout);
+
+        ret = mbedtls_x509write_crt_set_basic_constraints(&crt, opt.is_ca,
+                                                          opt.max_pathlen);
+        if (ret != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  x509write_crt_set_basic_constraints "
+                           "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        mbedtls_printf(" ok\n");
+    }
+
+#if defined(MBEDTLS_MD_CAN_SHA1)
+    if (opt.version == MBEDTLS_X509_CRT_VERSION_3 &&
+        opt.subject_identifier != 0) {
+        mbedtls_printf("  . Adding the Subject Key Identifier ...");
+        fflush(stdout);
+
+        ret = mbedtls_x509write_crt_set_subject_key_identifier(&crt);
+        if (ret != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_x509write_crt_set_subject"
+                           "_key_identifier returned -0x%04x - %s\n\n",
+                           (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        mbedtls_printf(" ok\n");
+    }
+
+    if (opt.version == MBEDTLS_X509_CRT_VERSION_3 &&
+        opt.authority_identifier != 0) {
+        mbedtls_printf("  . Adding the Authority Key Identifier ...");
+        fflush(stdout);
+
+        ret = mbedtls_x509write_crt_set_authority_key_identifier(&crt);
+        if (ret != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_x509write_crt_set_authority_"
+                           "key_identifier returned -0x%04x - %s\n\n",
+                           (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        mbedtls_printf(" ok\n");
+    }
+#endif /* MBEDTLS_MD_CAN_SHA1 */
+
+    if (opt.version == MBEDTLS_X509_CRT_VERSION_3 &&
+        opt.key_usage != 0) {
+        mbedtls_printf("  . Adding the Key Usage extension ...");
+        fflush(stdout);
+
+        ret = mbedtls_x509write_crt_set_key_usage(&crt, opt.key_usage);
+        if (ret != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_x509write_crt_set_key_usage "
+                           "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        mbedtls_printf(" ok\n");
+    }
+
+    if (opt.san_list != NULL) {
+        ret = mbedtls_x509write_crt_set_subject_alternative_name(&crt, opt.san_list);
+
+        if (ret != 0) {
+            mbedtls_printf(
+                " failed\n  !  mbedtls_x509write_crt_set_subject_alternative_name returned %d",
+                ret);
+            goto exit;
+        }
+    }
+
+    if (opt.ext_key_usage) {
+        mbedtls_printf("  . Adding the Extended Key Usage extension ...");
+        fflush(stdout);
+
+        ret = mbedtls_x509write_crt_set_ext_key_usage(&crt, opt.ext_key_usage);
+        if (ret != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(
+                " failed\n  !  mbedtls_x509write_crt_set_ext_key_usage returned -0x%02x - %s\n\n",
+                (unsigned int) -ret,
+                buf);
+            goto exit;
+        }
+
+        mbedtls_printf(" ok\n");
+    }
+
+    if (opt.version == MBEDTLS_X509_CRT_VERSION_3 &&
+        opt.ns_cert_type != 0) {
+        mbedtls_printf("  . Adding the NS Cert Type extension ...");
+        fflush(stdout);
+
+        ret = mbedtls_x509write_crt_set_ns_cert_type(&crt, opt.ns_cert_type);
+        if (ret != 0) {
+            mbedtls_strerror(ret, buf, sizeof(buf));
+            mbedtls_printf(" failed\n  !  mbedtls_x509write_crt_set_ns_cert_type "
+                           "returned -0x%04x - %s\n\n", (unsigned int) -ret, buf);
+            goto exit;
+        }
+
+        mbedtls_printf(" ok\n");
+    }
+
+    /*
+     * 1.2. Writing the certificate
+     */
+    mbedtls_printf("  . Writing the certificate...");
+    fflush(stdout);
+
+    if ((ret = write_certificate(&crt, opt.output_file,
+                                 mbedtls_ctr_drbg_random, &ctr_drbg)) != 0) {
+        mbedtls_strerror(ret, buf, sizeof(buf));
+        mbedtls_printf(" failed\n  !  write_certificate -0x%04x - %s\n\n",
+                       (unsigned int) -ret, buf);
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    exit_code = MBEDTLS_EXIT_SUCCESS;
+
+exit:
+#if defined(MBEDTLS_X509_CSR_PARSE_C)
+    mbedtls_x509_csr_free(&csr);
+#endif /* MBEDTLS_X509_CSR_PARSE_C */
+    mbedtls_asn1_free_named_data_list(&ext_san_dirname);
+    mbedtls_x509_crt_free(&issuer_crt);
+    mbedtls_x509write_crt_free(&crt);
+    mbedtls_pk_free(&loaded_subject_key);
+    mbedtls_pk_free(&loaded_issuer_key);
+    mbedtls_ctr_drbg_free(&ctr_drbg);
+    mbedtls_entropy_free(&entropy);
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_psa_crypto_free();
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    mbedtls_exit(exit_code);
+}
+#endif /* MBEDTLS_X509_CRT_WRITE_C && MBEDTLS_X509_CRT_PARSE_C &&
+          MBEDTLS_FS_IO && MBEDTLS_ENTROPY_C && MBEDTLS_CTR_DRBG_C &&
+          MBEDTLS_ERROR_C && MBEDTLS_PEM_WRITE_C */
diff --git a/programs/x509/crl_app.c b/programs/x509/crl_app.c
new file mode 100644
index 0000000..5e3fd5a
--- /dev/null
+++ b/programs/x509/crl_app.c
@@ -0,0 +1,132 @@
+/*
+ *  CRL reading application
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include "mbedtls/build_info.h"
+
+#include "mbedtls/platform.h"
+
+#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) ||  \
+    !defined(MBEDTLS_X509_CRL_PARSE_C) || !defined(MBEDTLS_FS_IO) || \
+    defined(MBEDTLS_X509_REMOVE_INFO)
+int main(void)
+{
+    mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
+                   "MBEDTLS_X509_CRL_PARSE_C and/or MBEDTLS_FS_IO not defined and/or "
+                   "MBEDTLS_X509_REMOVE_INFO defined.\n");
+    mbedtls_exit(0);
+}
+#else
+
+#include "mbedtls/x509_crl.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DFL_FILENAME            "crl.pem"
+#define DFL_DEBUG_LEVEL         0
+
+#define USAGE \
+    "\n usage: crl_app param=<>...\n"                   \
+    "\n acceptable parameters:\n"                       \
+    "    filename=%%s         default: crl.pem\n"      \
+    "\n"
+
+
+/*
+ * global options
+ */
+struct options {
+    const char *filename;       /* filename of the certificate file     */
+} opt;
+
+int main(int argc, char *argv[])
+{
+    int ret = 1;
+    int exit_code = MBEDTLS_EXIT_FAILURE;
+    unsigned char buf[100000];
+    mbedtls_x509_crl crl;
+    int i;
+    char *p, *q;
+
+    /*
+     * Set to sane values
+     */
+    mbedtls_x509_crl_init(&crl);
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_status_t status = psa_crypto_init();
+    if (status != PSA_SUCCESS) {
+        mbedtls_fprintf(stderr, "Failed to initialize PSA Crypto implementation: %d\n",
+                        (int) status);
+        goto exit;
+    }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    if (argc < 2) {
+usage:
+        mbedtls_printf(USAGE);
+        goto exit;
+    }
+
+    opt.filename            = DFL_FILENAME;
+
+    for (i = 1; i < argc; i++) {
+        p = argv[i];
+        if ((q = strchr(p, '=')) == NULL) {
+            goto usage;
+        }
+        *q++ = '\0';
+
+        if (strcmp(p, "filename") == 0) {
+            opt.filename = q;
+        } else {
+            goto usage;
+        }
+    }
+
+    /*
+     * 1.1. Load the CRL
+     */
+    mbedtls_printf("\n  . Loading the CRL ...");
+    fflush(stdout);
+
+    ret = mbedtls_x509_crl_parse_file(&crl, opt.filename);
+
+    if (ret != 0) {
+        mbedtls_printf(" failed\n  !  mbedtls_x509_crl_parse_file returned %d\n\n", ret);
+        mbedtls_x509_crl_free(&crl);
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    /*
+     * 1.2 Print the CRL
+     */
+    mbedtls_printf("  . CRL information    ...\n");
+    ret = mbedtls_x509_crl_info((char *) buf, sizeof(buf) - 1, "      ", &crl);
+    if (ret == -1) {
+        mbedtls_printf(" failed\n  !  mbedtls_x509_crl_info returned %d\n\n", ret);
+        mbedtls_x509_crl_free(&crl);
+        goto exit;
+    }
+
+    mbedtls_printf("%s\n", buf);
+
+    exit_code = MBEDTLS_EXIT_SUCCESS;
+
+exit:
+    mbedtls_x509_crl_free(&crl);
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_psa_crypto_free();
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    mbedtls_exit(exit_code);
+}
+#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_X509_CRL_PARSE_C &&
+          MBEDTLS_FS_IO */
diff --git a/programs/x509/load_roots.c b/programs/x509/load_roots.c
new file mode 100644
index 0000000..f0e6acf
--- /dev/null
+++ b/programs/x509/load_roots.c
@@ -0,0 +1,165 @@
+/*
+ *  Root CA reading application
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include "mbedtls/build_info.h"
+
+#include "mbedtls/platform.h"
+
+#if !defined(MBEDTLS_X509_CRT_PARSE_C) || !defined(MBEDTLS_FS_IO) ||  \
+    !defined(MBEDTLS_TIMING_C)
+int main(void)
+{
+    mbedtls_printf("MBEDTLS_X509_CRT_PARSE_C and/or MBEDTLS_FS_IO and/or "
+                   "MBEDTLS_TIMING_C not defined.\n");
+    mbedtls_exit(0);
+}
+#else
+
+#include "mbedtls/error.h"
+#include "mbedtls/timing.h"
+#include "mbedtls/x509_crt.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DFL_ITERATIONS          1
+#define DFL_PRIME_CACHE         1
+
+#define USAGE \
+    "\n usage: load_roots param=<>... [--] FILE...\n"   \
+    "\n acceptable parameters:\n"                       \
+    "    iterations=%%d        Iteration count (not including cache priming); default: 1\n"  \
+    "    prime=%%d             Prime the disk read cache? Default: 1 (yes)\n"  \
+    "\n"
+
+
+/*
+ * global options
+ */
+struct options {
+    const char **filenames;     /* NULL-terminated list of file names */
+    unsigned iterations;        /* Number of iterations to time */
+    int prime_cache;            /* Prime the disk read cache? */
+} opt;
+
+
+int read_certificates(const char *const *filenames)
+{
+    mbedtls_x509_crt cas;
+    int ret = 0;
+    const char *const *cur;
+
+    mbedtls_x509_crt_init(&cas);
+
+    for (cur = filenames; *cur != NULL; cur++) {
+        ret = mbedtls_x509_crt_parse_file(&cas, *cur);
+        if (ret != 0) {
+#if defined(MBEDTLS_ERROR_C) || defined(MBEDTLS_ERROR_STRERROR_DUMMY)
+            char error_message[200];
+            mbedtls_strerror(ret, error_message, sizeof(error_message));
+            printf("\n%s: -0x%04x (%s)\n",
+                   *cur, (unsigned) -ret, error_message);
+#else
+            printf("\n%s: -0x%04x\n",
+                   *cur, (unsigned) -ret);
+#endif
+            goto exit;
+        }
+    }
+
+exit:
+    mbedtls_x509_crt_free(&cas);
+    return ret == 0;
+}
+
+int main(int argc, char *argv[])
+{
+    int exit_code = MBEDTLS_EXIT_FAILURE;
+    unsigned i, j;
+    struct mbedtls_timing_hr_time timer;
+    unsigned long ms;
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_status_t status = psa_crypto_init();
+    if (status != PSA_SUCCESS) {
+        mbedtls_fprintf(stderr, "Failed to initialize PSA Crypto implementation: %d\n",
+                        (int) status);
+        goto exit;
+    }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    if (argc <= 1) {
+        mbedtls_printf(USAGE);
+        goto exit;
+    }
+
+    opt.filenames = NULL;
+    opt.iterations = DFL_ITERATIONS;
+    opt.prime_cache = DFL_PRIME_CACHE;
+
+    for (i = 1; i < (unsigned) argc; i++) {
+        char *p = argv[i];
+        char *q = NULL;
+
+        if (strcmp(p, "--") == 0) {
+            break;
+        }
+        if ((q = strchr(p, '=')) == NULL) {
+            break;
+        }
+        *q++ = '\0';
+
+        for (j = 0; p + j < q; j++) {
+            if (argv[i][j] >= 'A' && argv[i][j] <= 'Z') {
+                argv[i][j] |= 0x20;
+            }
+        }
+
+        if (strcmp(p, "iterations") == 0) {
+            opt.iterations = atoi(q);
+        } else if (strcmp(p, "prime") == 0) {
+            opt.iterations = atoi(q) != 0;
+        } else {
+            mbedtls_printf("Unknown option: %s\n", p);
+            mbedtls_printf(USAGE);
+            goto exit;
+        }
+    }
+
+    opt.filenames = (const char **) argv + i;
+    if (*opt.filenames == 0) {
+        mbedtls_printf("Missing list of certificate files to parse\n");
+        goto exit;
+    }
+
+    mbedtls_printf("Parsing %u certificates", argc - i);
+    if (opt.prime_cache) {
+        if (!read_certificates(opt.filenames)) {
+            goto exit;
+        }
+        mbedtls_printf(" ");
+    }
+
+    (void) mbedtls_timing_get_timer(&timer, 1);
+    for (i = 1; i <= opt.iterations; i++) {
+        if (!read_certificates(opt.filenames)) {
+            goto exit;
+        }
+        mbedtls_printf(".");
+    }
+    ms = mbedtls_timing_get_timer(&timer, 0);
+    mbedtls_printf("\n%u iterations -> %lu ms\n", opt.iterations, ms);
+    exit_code = MBEDTLS_EXIT_SUCCESS;
+
+exit:
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_psa_crypto_free();
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    mbedtls_exit(exit_code);
+}
+#endif /* necessary configuration */
diff --git a/programs/x509/req_app.c b/programs/x509/req_app.c
new file mode 100644
index 0000000..fff0983
--- /dev/null
+++ b/programs/x509/req_app.c
@@ -0,0 +1,132 @@
+/*
+ *  Certificate request reading application
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include "mbedtls/build_info.h"
+
+#include "mbedtls/platform.h"
+
+#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) ||  \
+    !defined(MBEDTLS_X509_CSR_PARSE_C) || !defined(MBEDTLS_FS_IO) || \
+    defined(MBEDTLS_X509_REMOVE_INFO)
+int main(void)
+{
+    mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
+                   "MBEDTLS_X509_CSR_PARSE_C and/or MBEDTLS_FS_IO not defined and/or "
+                   "MBEDTLS_X509_REMOVE_INFO defined.\n");
+    mbedtls_exit(0);
+}
+#else
+
+#include "mbedtls/x509_csr.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DFL_FILENAME            "cert.req"
+#define DFL_DEBUG_LEVEL         0
+
+#define USAGE \
+    "\n usage: req_app param=<>...\n"                   \
+    "\n acceptable parameters:\n"                       \
+    "    filename=%%s         default: cert.req\n"      \
+    "\n"
+
+
+/*
+ * global options
+ */
+struct options {
+    const char *filename;       /* filename of the certificate request  */
+} opt;
+
+int main(int argc, char *argv[])
+{
+    int ret = 1;
+    int exit_code = MBEDTLS_EXIT_FAILURE;
+    unsigned char buf[100000];
+    mbedtls_x509_csr csr;
+    int i;
+    char *p, *q;
+
+    /*
+     * Set to sane values
+     */
+    mbedtls_x509_csr_init(&csr);
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_status_t status = psa_crypto_init();
+    if (status != PSA_SUCCESS) {
+        mbedtls_fprintf(stderr, "Failed to initialize PSA Crypto implementation: %d\n",
+                        (int) status);
+        goto exit;
+    }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    if (argc < 2) {
+usage:
+        mbedtls_printf(USAGE);
+        goto exit;
+    }
+
+    opt.filename            = DFL_FILENAME;
+
+    for (i = 1; i < argc; i++) {
+        p = argv[i];
+        if ((q = strchr(p, '=')) == NULL) {
+            goto usage;
+        }
+        *q++ = '\0';
+
+        if (strcmp(p, "filename") == 0) {
+            opt.filename = q;
+        } else {
+            goto usage;
+        }
+    }
+
+    /*
+     * 1.1. Load the CSR
+     */
+    mbedtls_printf("\n  . Loading the CSR ...");
+    fflush(stdout);
+
+    ret = mbedtls_x509_csr_parse_file(&csr, opt.filename);
+
+    if (ret != 0) {
+        mbedtls_printf(" failed\n  !  mbedtls_x509_csr_parse_file returned %d\n\n", ret);
+        mbedtls_x509_csr_free(&csr);
+        goto exit;
+    }
+
+    mbedtls_printf(" ok\n");
+
+    /*
+     * 1.2 Print the CSR
+     */
+    mbedtls_printf("  . CSR information    ...\n");
+    ret = mbedtls_x509_csr_info((char *) buf, sizeof(buf) - 1, "      ", &csr);
+    if (ret == -1) {
+        mbedtls_printf(" failed\n  !  mbedtls_x509_csr_info returned %d\n\n", ret);
+        mbedtls_x509_csr_free(&csr);
+        goto exit;
+    }
+
+    mbedtls_printf("%s\n", buf);
+
+    exit_code = MBEDTLS_EXIT_SUCCESS;
+
+exit:
+    mbedtls_x509_csr_free(&csr);
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_psa_crypto_free();
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    mbedtls_exit(exit_code);
+}
+#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_X509_CSR_PARSE_C &&
+          MBEDTLS_FS_IO */