| /* |
| * Copyright 2021-2022 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 rv = 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; |
| } |
| |
| rv = EXIT_SUCCESS; |
| end: |
| EVP_MAC_CTX_free(mctx); |
| EVP_MAC_free(mac); |
| OSSL_LIB_CTX_free(library_context); |
| if (rv != EXIT_SUCCESS) |
| ERR_print_errors_fp(stderr); |
| return rv; |
| } |