diff --git a/services/std_svc/rmmd/rmmd.mk b/services/std_svc/rmmd/rmmd.mk
index bac0a9f..bcf54e1 100644
--- a/services/std_svc/rmmd/rmmd.mk
+++ b/services/std_svc/rmmd/rmmd.mk
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2021-2022, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -12,7 +12,8 @@
 
 RMMD_SOURCES	+=	$(addprefix services/std_svc/rmmd/,	\
 			${ARCH}/rmmd_helpers.S			\
-			rmmd_main.c)
+			rmmd_main.c				\
+			rmmd_attest.c)
 
 # Let the top-level Makefile know that we intend to include RMM image
 NEED_RMM	:=	yes
diff --git a/services/std_svc/rmmd/rmmd_attest.c b/services/std_svc/rmmd/rmmd_attest.c
new file mode 100644
index 0000000..d111b88
--- /dev/null
+++ b/services/std_svc/rmmd/rmmd_attest.c
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2022, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#include <stdint.h>
+#include <string.h>
+#include <common/debug.h>
+#include <lib/spinlock.h>
+#include <lib/xlat_tables/xlat_tables_v2.h>
+#include <plat/common/platform.h>
+#include "rmmd_private.h"
+#include <services/rmmd_svc.h>
+
+static spinlock_t lock;
+
+/* For printing Realm attestation token hash */
+#define DIGITS_PER_BYTE				2UL
+#define LENGTH_OF_TERMINATING_ZERO_IN_BYTES	1UL
+#define BYTES_PER_LINE_BASE			4UL
+
+static void print_challenge(uint8_t *hash, size_t hash_size)
+{
+	size_t leftover;
+	/*
+	 * bytes_per_line is always a power of two, so it can be used to
+	 * construct mask with it when it is necessary to count remainder.
+	 *
+	 */
+	const size_t bytes_per_line = 1 << BYTES_PER_LINE_BASE;
+	char hash_text[(1 << BYTES_PER_LINE_BASE) * DIGITS_PER_BYTE +
+		LENGTH_OF_TERMINATING_ZERO_IN_BYTES];
+	const char hex_chars[] = {'0', '1', '2', '3', '4', '5', '6', '7',
+				  '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
+	unsigned int i;
+
+	for (i = 0U; i < hash_size; ++i) {
+		hash_text[(i & (bytes_per_line - 1)) * DIGITS_PER_BYTE] =
+			hex_chars[hash[i] >> 4];
+		hash_text[(i & (bytes_per_line - 1)) * DIGITS_PER_BYTE + 1] =
+			hex_chars[hash[i] & 0x0f];
+		if (((i + 1) & (bytes_per_line - 1)) == 0U) {
+			hash_text[bytes_per_line * DIGITS_PER_BYTE] = '\0';
+			VERBOSE("hash part %u = %s\n",
+				(i >> BYTES_PER_LINE_BASE) + 1, hash_text);
+		}
+	}
+
+	leftover = (size_t)i & (bytes_per_line - 1);
+
+	if (leftover != 0UL) {
+		hash_text[leftover * DIGITS_PER_BYTE] = '\0';
+		VERBOSE("hash part %u = %s\n", (i >> BYTES_PER_LINE_BASE) + 1,
+			hash_text);
+	}
+}
+
+/*
+ * TODO: Have different error codes for different errors so that the caller can
+ * differentiate various error cases.
+ */
+int rmmd_attest_get_platform_token(uint64_t buf_pa, uint64_t *buf_len, uint64_t challenge_hash_len)
+{
+	int err;
+	uintptr_t va;
+	uint8_t temp_buf[SHA512_DIGEST_SIZE];
+
+	/*
+	 * TODO: Currently we don't validate incoming buf_pa. This is a
+	 * prototype and we will need to allocate static buffer for EL3-RMM
+	 * communication.
+	 */
+
+	/* We need a page of buffer to pass data */
+	if (*buf_len != PAGE_SIZE) {
+		ERROR("Invalid buffer length\n");
+		return RMMD_ERR_INVAL;
+	}
+
+	if ((challenge_hash_len != SHA256_DIGEST_SIZE) &&
+	    (challenge_hash_len != SHA384_DIGEST_SIZE) &&
+	    (challenge_hash_len != SHA512_DIGEST_SIZE)) {
+		ERROR("Invalid hash size: %lu\n", challenge_hash_len);
+		return RMMD_ERR_INVAL;
+	}
+
+	spin_lock(&lock);
+
+	/* Map the buffer that was provided by the RMM. */
+	err = mmap_add_dynamic_region_alloc_va(buf_pa, &va, PAGE_SIZE,
+					       MT_RW_DATA | MT_REALM);
+	if (err != 0) {
+		ERROR("mmap_add_dynamic_region_alloc_va failed: %d (%p).\n"
+		      , err, (void *)buf_pa);
+		spin_unlock(&lock);
+		return RMMD_ERR_NOMEM;
+	}
+
+	(void)memcpy(temp_buf, (void *)va, challenge_hash_len);
+
+	print_challenge((uint8_t *)temp_buf, challenge_hash_len);
+
+	/* Get the platform token. */
+	err = plat_get_cca_attest_token(va,
+		buf_len, (uintptr_t)temp_buf, challenge_hash_len);
+
+	if (err != 0) {
+		ERROR("Failed to get platform token: %d.\n", err);
+		err = RMMD_ERR_UNK;
+	}
+
+	/* Unmap RMM memory. */
+	(void)mmap_remove_dynamic_region(va, PAGE_SIZE);
+	spin_unlock(&lock);
+
+	return err;
+}
+
diff --git a/services/std_svc/rmmd/rmmd_main.c b/services/std_svc/rmmd/rmmd_main.c
index 7f4a010..c59e68a 100644
--- a/services/std_svc/rmmd/rmmd_main.c
+++ b/services/std_svc/rmmd/rmmd_main.c
@@ -372,6 +372,9 @@
 	case RMMD_GTSI_UNDELEGATE:
 		ret = gpt_undelegate_pas(x1, PAGE_SIZE_4KB, SMC_FROM_REALM);
 		SMC_RET1(handle, gpt_to_gts_error(ret, smc_fid, x1));
+	case RMMD_ATTEST_GET_PLAT_TOKEN:
+		ret = rmmd_attest_get_platform_token(x1, &x2, x3);
+		SMC_RET2(handle, ret, x2);
 	default:
 		WARN("RMMD: Unsupported RMM-EL3 call 0x%08x\n", smc_fid);
 		SMC_RET1(handle, SMC_UNK);
diff --git a/services/std_svc/rmmd/rmmd_private.h b/services/std_svc/rmmd/rmmd_private.h
index ca2c37c..d7ef4e1 100644
--- a/services/std_svc/rmmd/rmmd_private.h
+++ b/services/std_svc/rmmd/rmmd_private.h
@@ -51,6 +51,10 @@
 uint64_t rmmd_rmm_sync_entry(rmmd_rmm_context_t *ctx);
 __dead2 void rmmd_rmm_sync_exit(uint64_t rc);
 
+/* Functions implementing attestation utilities for RMM */
+int rmmd_attest_get_platform_token(uint64_t buf_pa, uint64_t *buf_len,
+				   uint64_t challenge_hash_len);
+
 /* Assembly helpers */
 uint64_t rmmd_rmm_enter(uint64_t *c_rt_ctx);
 void __dead2 rmmd_rmm_exit(uint64_t c_rt_ctx, uint64_t ret);