quickjs-tart

quickjs-based runtime for wallet-core logic
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md_hmac_demo.c (4685B)

      1 /**
      2  * MD API multi-part HMAC demonstration.
      3  *
      4  * This programs computes the HMAC of two messages using the multi-part API.
      5  *
      6  * This is a companion to psa/hmac_demo.c, doing the same operations with the
      7  * legacy MD API. The goal is that comparing the two programs will help people
      8  * migrating to the PSA Crypto API.
      9  *
     10  * When it comes to multi-part HMAC operations, the `mbedtls_md_context`
     11  * serves a dual purpose (1) hold the key, and (2) save progress information
     12  * for the current operation. With PSA those roles are held by two disinct
     13  * objects: (1) a psa_key_id_t to hold the key, and (2) a psa_operation_t for
     14  * multi-part progress.
     15  *
     16  * This program and its companion psa/hmac_demo.c illustrate this by doing the
     17  * same sequence of multi-part HMAC computation with both APIs; looking at the
     18  * two side by side should make the differences and similarities clear.
     19  */
     20 
     21 /*
     22  *  Copyright The Mbed TLS Contributors
     23  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
     24  */
     25 
     26 /* First include Mbed TLS headers to get the Mbed TLS configuration and
     27  * platform definitions that we'll use in this program. Also include
     28  * standard C headers for functions we'll use here. */
     29 #include "mbedtls/build_info.h"
     30 
     31 #include "mbedtls/md.h"
     32 
     33 #include "mbedtls/platform_util.h" // for mbedtls_platform_zeroize
     34 
     35 #include <stdlib.h>
     36 #include <stdio.h>
     37 
     38 /* If the build options we need are not enabled, compile a placeholder. */
     39 #if !defined(MBEDTLS_MD_C)
     40 int main(void)
     41 {
     42     printf("MBEDTLS_MD_C not defined\r\n");
     43     return 0;
     44 }
     45 #else
     46 
     47 /* The real program starts here. */
     48 
     49 /* Dummy inputs for HMAC */
     50 const unsigned char msg1_part1[] = { 0x01, 0x02 };
     51 const unsigned char msg1_part2[] = { 0x03, 0x04 };
     52 const unsigned char msg2_part1[] = { 0x05, 0x05 };
     53 const unsigned char msg2_part2[] = { 0x06, 0x06 };
     54 
     55 /* Dummy key material - never do this in production!
     56  * This example program uses SHA-256, so a 32-byte key makes sense. */
     57 const unsigned char key_bytes[32] = { 0 };
     58 
     59 /* Print the contents of a buffer in hex */
     60 static void print_buf(const char *title, unsigned char *buf, size_t len)
     61 {
     62     printf("%s:", title);
     63     for (size_t i = 0; i < len; i++) {
     64         printf(" %02x", buf[i]);
     65     }
     66     printf("\n");
     67 }
     68 
     69 /* Run an Mbed TLS function and bail out if it fails.
     70  * A string description of the error code can be recovered with:
     71  * programs/util/strerror <value> */
     72 #define CHK(expr)                                             \
     73     do                                                          \
     74     {                                                           \
     75         ret = (expr);                                         \
     76         if (ret != 0)                                          \
     77         {                                                       \
     78             printf("Error %d at line %d: %s\n",                \
     79                    ret,                                        \
     80                    __LINE__,                                   \
     81                    #expr);                                    \
     82             goto exit;                                          \
     83         }                                                       \
     84     } while (0)
     85 
     86 /*
     87  * This function demonstrates computation of the HMAC of two messages using
     88  * the multipart API.
     89  */
     90 static int hmac_demo(void)
     91 {
     92     int ret;
     93     const mbedtls_md_type_t alg = MBEDTLS_MD_SHA256;
     94     unsigned char out[MBEDTLS_MD_MAX_SIZE]; // safe but not optimal
     95 
     96     mbedtls_md_context_t ctx;
     97 
     98     mbedtls_md_init(&ctx);
     99 
    100     /* prepare context and load key */
    101     // the last argument to setup is 1 to enable HMAC (not just hashing)
    102     const mbedtls_md_info_t *info = mbedtls_md_info_from_type(alg);
    103     CHK(mbedtls_md_setup(&ctx, info, 1));
    104     CHK(mbedtls_md_hmac_starts(&ctx, key_bytes, sizeof(key_bytes)));
    105 
    106     /* compute HMAC(key, msg1_part1 | msg1_part2) */
    107     CHK(mbedtls_md_hmac_update(&ctx, msg1_part1, sizeof(msg1_part1)));
    108     CHK(mbedtls_md_hmac_update(&ctx, msg1_part2, sizeof(msg1_part2)));
    109     CHK(mbedtls_md_hmac_finish(&ctx, out));
    110     print_buf("msg1", out, mbedtls_md_get_size(info));
    111 
    112     /* compute HMAC(key, msg2_part1 | msg2_part2) */
    113     CHK(mbedtls_md_hmac_reset(&ctx));     // prepare for new operation
    114     CHK(mbedtls_md_hmac_update(&ctx, msg2_part1, sizeof(msg2_part1)));
    115     CHK(mbedtls_md_hmac_update(&ctx, msg2_part2, sizeof(msg2_part2)));
    116     CHK(mbedtls_md_hmac_finish(&ctx, out));
    117     print_buf("msg2", out, mbedtls_md_get_size(info));
    118 
    119 exit:
    120     mbedtls_md_free(&ctx);
    121     mbedtls_platform_zeroize(out, sizeof(out));
    122 
    123     return ret;
    124 }
    125 
    126 int main(void)
    127 {
    128     int ret;
    129 
    130     CHK(hmac_demo());
    131 
    132 exit:
    133     return ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
    134 }
    135 
    136 #endif