MINOR: quic-tls: Add quic_hkdf_extract_and_expand() for HKDF
This is a wrapper function around OpenSSL HKDF API functions to
use the "extract-then-expand" HKDF mode as defined by rfc5869.
This function will be used to derived stateless reset tokens
from secrets ("cluster-secret" conf. keyword) and CIDs (as salts).
diff --git a/include/haproxy/quic_tls.h b/include/haproxy/quic_tls.h
index 8616aa3..0a0483d 100644
--- a/include/haproxy/quic_tls.h
+++ b/include/haproxy/quic_tls.h
@@ -79,6 +79,12 @@
unsigned char *hp_key, size_t hp_keylen,
const unsigned char *secret, size_t secretlen);
+int quic_hkdf_extract_and_expand(const EVP_MD *md,
+ unsigned char *buf, size_t buflen,
+ const unsigned char *key, size_t keylen,
+ const unsigned char *salt, size_t saltlen,
+ const unsigned char *label, size_t labellen);
+
int quic_tls_rx_ctx_init(EVP_CIPHER_CTX **rx_ctx,
const EVP_CIPHER *aead, unsigned char *key);
int quic_tls_tx_ctx_init(EVP_CIPHER_CTX **tx_ctx,
diff --git a/src/quic_tls.c b/src/quic_tls.c
index f8d11a3..12a2133 100644
--- a/src/quic_tls.c
+++ b/src/quic_tls.c
@@ -123,6 +123,44 @@
EVP_PKEY_CTX_free(ctx);
return 0;
}
+
+/* Extracts a peudo-random secret key from <key> which is eventually not
+ * pseudo-random and expand it to a new pseudo-random key into
+ * <buf> with <buflen> as key length according to HKDF specifications
+ * (https://datatracker.ietf.org/doc/html/rfc5869).
+ * According to this specifications it is highly recommended to use
+ * a salt, even if optional (NULL value).
+ * Return 1 if succeeded, 0 if not.
+ */
+int quic_hkdf_extract_and_expand(const EVP_MD *md,
+ unsigned char *buf, size_t buflen,
+ const unsigned char *key, size_t keylen,
+ const unsigned char *salt, size_t saltlen,
+ const unsigned char *label, size_t labellen)
+{
+ EVP_PKEY_CTX *ctx;
+
+ ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
+ if (!ctx)
+ return 0;
+
+ if (EVP_PKEY_derive_init(ctx) <= 0 ||
+ EVP_PKEY_CTX_hkdf_mode(ctx, EVP_PKEY_HKDEF_MODE_EXTRACT_AND_EXPAND) <= 0 ||
+ EVP_PKEY_CTX_set_hkdf_md(ctx, md) <= 0 ||
+ EVP_PKEY_CTX_set1_hkdf_salt(ctx, salt, saltlen) <= 0 ||
+ EVP_PKEY_CTX_set1_hkdf_key(ctx, key, keylen) <= 0 ||
+ EVP_PKEY_CTX_add1_hkdf_info(ctx, label, labellen) <= 0 ||
+ EVP_PKEY_derive(ctx, buf, &buflen) <= 0)
+ goto err;
+
+ EVP_PKEY_CTX_free(ctx);
+ return 1;
+
+ err:
+ EVP_PKEY_CTX_free(ctx);
+ return 0;
+}
+
#endif
/* https://quicwg.org/base-drafts/draft-ietf-quic-tls.html#protection-keys