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Diffstat (limited to 'programs/psa/hmac_demo.c')
| -rw-r--r-- | programs/psa/hmac_demo.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/programs/psa/hmac_demo.c b/programs/psa/hmac_demo.c new file mode 100644 index 00000000000..205505407fb --- /dev/null +++ b/programs/psa/hmac_demo.c @@ -0,0 +1,159 @@ +/** + * PSA API multi-part HMAC demonstration. + * + * This programs computes the HMAC of two messages using the multi-part API. + * + * It comes with a companion program hash/md_hmac_demo.c, which does the same + * operations with the legacy MD API. The goal is that comparing the two + * programs will help people migrating to the PSA Crypto API. + * + * When it comes to multi-part HMAC operations, the `mbedtls_md_context` + * serves a dual purpose (1) hold the key, and (2) save progress information + * for the current operation. With PSA those roles are held by two disinct + * objects: (1) a psa_key_id_t to hold the key, and (2) a psa_operation_t for + * multi-part progress. + * + * This program and its companion hash/md_hmac_demo.c illustrate this by doing + * the same sequence of multi-part HMAC computation with both APIs; looking at + * the two side by side should make the differences and similarities clear. + */ + +/* + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ + +/* First include Mbed TLS headers to get the Mbed TLS configuration and + * platform definitions that we'll use in this program. Also include + * standard C headers for functions we'll use here. */ +#include "mbedtls/build_info.h" + +#include "psa/crypto.h" + +#include "mbedtls/platform_util.h" // for mbedtls_platform_zeroize + +#include <stdlib.h> +#include <stdio.h> + +/* If the build options we need are not enabled, compile a placeholder. */ +#if !defined(MBEDTLS_PSA_CRYPTO_C) || \ + defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER) +int main(void) +{ + printf("MBEDTLS_PSA_CRYPTO_C not defined, " + "and/or MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER defined\r\n"); + return 0; +} +#else + +/* The real program starts here. */ + +/* Dummy inputs for HMAC */ +const unsigned char msg1_part1[] = { 0x01, 0x02 }; +const unsigned char msg1_part2[] = { 0x03, 0x04 }; +const unsigned char msg2_part1[] = { 0x05, 0x05 }; +const unsigned char msg2_part2[] = { 0x06, 0x06 }; + +/* Dummy key material - never do this in production! + * This example program uses SHA-256, so a 32-byte key makes sense. */ +const unsigned char key_bytes[32] = { 0 }; + +/* Print the contents of a buffer in hex */ +void print_buf(const char *title, uint8_t *buf, size_t len) +{ + printf("%s:", title); + for (size_t i = 0; i < len; i++) { + printf(" %02x", buf[i]); + } + printf("\n"); +} + +/* Run a PSA function and bail out if it fails. + * The symbolic name of the error code can be recovered using: + * programs/psa/psa_constant_name status <value> */ +#define PSA_CHECK(expr) \ + do \ + { \ + status = (expr); \ + if (status != PSA_SUCCESS) \ + { \ + printf("Error %d at line %d: %s\n", \ + (int) status, \ + __LINE__, \ + #expr); \ + goto exit; \ + } \ + } \ + while (0) + +/* + * This function demonstrates computation of the HMAC of two messages using + * the multipart API. + */ +psa_status_t hmac_demo(void) +{ + psa_status_t status; + const psa_algorithm_t alg = PSA_ALG_HMAC(PSA_ALG_SHA_256); + uint8_t out[PSA_MAC_MAX_SIZE]; // safe but not optimal + /* PSA_MAC_LENGTH(PSA_KEY_TYPE_HMAC, 8 * sizeof( key_bytes ), alg) + * should work but see https://github.com/Mbed-TLS/mbedtls/issues/4320 */ + + psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; + psa_key_id_t key = 0; + + /* prepare key */ + psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_MESSAGE); + psa_set_key_algorithm(&attributes, alg); + psa_set_key_type(&attributes, PSA_KEY_TYPE_HMAC); + psa_set_key_bits(&attributes, 8 * sizeof(key_bytes)); // optional + + status = psa_import_key(&attributes, + key_bytes, sizeof(key_bytes), &key); + if (status != PSA_SUCCESS) { + return status; + } + + /* prepare operation */ + psa_mac_operation_t op = PSA_MAC_OPERATION_INIT; + size_t out_len = 0; + + /* compute HMAC(key, msg1_part1 | msg1_part2) */ + PSA_CHECK(psa_mac_sign_setup(&op, key, alg)); + PSA_CHECK(psa_mac_update(&op, msg1_part1, sizeof(msg1_part1))); + PSA_CHECK(psa_mac_update(&op, msg1_part2, sizeof(msg1_part2))); + PSA_CHECK(psa_mac_sign_finish(&op, out, sizeof(out), &out_len)); + print_buf("msg1", out, out_len); + + /* compute HMAC(key, msg2_part1 | msg2_part2) */ + PSA_CHECK(psa_mac_sign_setup(&op, key, alg)); + PSA_CHECK(psa_mac_update(&op, msg2_part1, sizeof(msg2_part1))); + PSA_CHECK(psa_mac_update(&op, msg2_part2, sizeof(msg2_part2))); + PSA_CHECK(psa_mac_sign_finish(&op, out, sizeof(out), &out_len)); + print_buf("msg2", out, out_len); + +exit: + psa_mac_abort(&op); // needed on error, harmless on success + psa_destroy_key(key); + mbedtls_platform_zeroize(out, sizeof(out)); + + return status; +} + +int main(void) +{ + psa_status_t status = PSA_SUCCESS; + + /* Initialize the PSA crypto library. */ + PSA_CHECK(psa_crypto_init()); + + /* Run the demo */ + PSA_CHECK(hmac_demo()); + + /* Deinitialize the PSA crypto library. */ + mbedtls_psa_crypto_free(); + +exit: + return status == PSA_SUCCESS ? EXIT_SUCCESS : EXIT_FAILURE; +} + +#endif |