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- /*
- * Copyright 2021-2023 The OpenSSL Project Authors. All Rights Reserved.
- *
- * Licensed under the Apache License 2.0 (the "License"). You may not use
- * this file except in compliance with the License. You can obtain a copy
- * in the file LICENSE in the source distribution or at
- * https://www.openssl.org/source/license.html
- */
- #include <stdio.h>
- #include <stdlib.h>
- #include <openssl/core_names.h>
- #include <openssl/evp.h>
- #include <openssl/params.h>
- #include <openssl/err.h>
- /*
- * Taken from NIST's GCM Test Vectors
- * http://csrc.nist.gov/groups/STM/cavp/
- */
- /*
- * Hard coding the key into an application is very bad.
- * It is done here solely for educational purposes.
- */
- static unsigned char key[] = {
- 0x77, 0xbe, 0x63, 0x70, 0x89, 0x71, 0xc4, 0xe2,
- 0x40, 0xd1, 0xcb, 0x79, 0xe8, 0xd7, 0x7f, 0xeb
- };
- /*
- * The initialisation vector (IV) is better not being hard coded too.
- * Repeating password/IV pairs compromises the integrity of GMAC.
- * The IV is not considered secret information and is safe to store with
- * an encrypted password.
- */
- static unsigned char iv[] = {
- 0xe0, 0xe0, 0x0f, 0x19, 0xfe, 0xd7, 0xba,
- 0x01, 0x36, 0xa7, 0x97, 0xf3
- };
- static unsigned char data[] = {
- 0x7a, 0x43, 0xec, 0x1d, 0x9c, 0x0a, 0x5a, 0x78,
- 0xa0, 0xb1, 0x65, 0x33, 0xa6, 0x21, 0x3c, 0xab
- };
- static const unsigned char expected_output[] = {
- 0x20, 0x9f, 0xcc, 0x8d, 0x36, 0x75, 0xed, 0x93,
- 0x8e, 0x9c, 0x71, 0x66, 0x70, 0x9d, 0xd9, 0x46
- };
- /*
- * A property query used for selecting the GMAC implementation and the
- * underlying GCM mode cipher.
- */
- static char *propq = NULL;
- int main(int argc, char **argv)
- {
- int ret = EXIT_FAILURE;
- EVP_MAC *mac = NULL;
- EVP_MAC_CTX *mctx = NULL;
- unsigned char out[16];
- OSSL_PARAM params[4], *p = params;
- OSSL_LIB_CTX *library_context = NULL;
- size_t out_len = 0;
- library_context = OSSL_LIB_CTX_new();
- if (library_context == NULL) {
- fprintf(stderr, "OSSL_LIB_CTX_new() returned NULL\n");
- goto end;
- }
- /* Fetch the GMAC implementation */
- mac = EVP_MAC_fetch(library_context, "GMAC", propq);
- if (mac == NULL) {
- fprintf(stderr, "EVP_MAC_fetch() returned NULL\n");
- goto end;
- }
- /* Create a context for the GMAC operation */
- mctx = EVP_MAC_CTX_new(mac);
- if (mctx == NULL) {
- fprintf(stderr, "EVP_MAC_CTX_new() returned NULL\n");
- goto end;
- }
- /* GMAC requires a GCM mode cipher to be specified */
- *p++ = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_CIPHER,
- "AES-128-GCM", 0);
- /*
- * If a non-default property query is required when fetching the GCM mode
- * cipher, it needs to be specified too.
- */
- if (propq != NULL)
- *p++ = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_PROPERTIES,
- propq, 0);
- /* Set the initialisation vector (IV) */
- *p++ = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_IV,
- iv, sizeof(iv));
- *p = OSSL_PARAM_construct_end();
- /* Initialise the GMAC operation */
- if (!EVP_MAC_init(mctx, key, sizeof(key), params)) {
- fprintf(stderr, "EVP_MAC_init() failed\n");
- goto end;
- }
- /* Make one or more calls to process the data to be authenticated */
- if (!EVP_MAC_update(mctx, data, sizeof(data))) {
- fprintf(stderr, "EVP_MAC_update() failed\n");
- goto end;
- }
- /* Make one call to the final to get the MAC */
- if (!EVP_MAC_final(mctx, out, &out_len, sizeof(out))) {
- fprintf(stderr, "EVP_MAC_final() failed\n");
- goto end;
- }
- printf("Generated MAC:\n");
- BIO_dump_indent_fp(stdout, out, out_len, 2);
- putchar('\n');
- if (out_len != sizeof(expected_output)) {
- fprintf(stderr, "Generated MAC has an unexpected length\n");
- goto end;
- }
- if (CRYPTO_memcmp(expected_output, out, sizeof(expected_output)) != 0) {
- fprintf(stderr, "Generated MAC does not match expected value\n");
- goto end;
- }
- ret = EXIT_SUCCESS;
- end:
- EVP_MAC_CTX_free(mctx);
- EVP_MAC_free(mac);
- OSSL_LIB_CTX_free(library_context);
- if (ret != EXIT_SUCCESS)
- ERR_print_errors_fp(stderr);
- return ret;
- }
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