pk_sign.c

/*
 *  Public key-based signature creation program
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */

#define MBEDTLS_DECLARE_PRIVATE_IDENTIFIERS

#include "mbedtls/build_info.h"

#include "mbedtls/platform.h"
/* md.h is included this early since MD_CAN_XXX macros are defined there. */
#include "mbedtls/md.h"

#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_ENTROPY_C) ||  \
    !defined(PSA_WANT_ALG_SHA_256) || !defined(MBEDTLS_MD_C) || \
    !defined(MBEDTLS_PK_PARSE_C) || !defined(MBEDTLS_FS_IO) ||    \
    !defined(MBEDTLS_CTR_DRBG_C)
int main(void)
{
    mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_ENTROPY_C and/or "
                   "PSA_WANT_ALG_SHA_256 and/or MBEDTLS_MD_C and/or "
                   "MBEDTLS_PK_PARSE_C and/or MBEDTLS_FS_IO and/or "
                   "MBEDTLS_CTR_DRBG_C not defined.\n");
    mbedtls_exit(0);
}
#else

#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/pk.h"

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[])
{
    FILE *f;
    int ret = 1;
    int exit_code = MBEDTLS_EXIT_FAILURE;
    mbedtls_pk_context pk;
    mbedtls_entropy_context entropy;
    mbedtls_ctr_drbg_context ctr_drbg;
    unsigned char hash[32];
    unsigned char buf[MBEDTLS_PK_SIGNATURE_MAX_SIZE];
    char filename[512];
    const char *pers = "mbedtls_pk_sign";
    size_t olen = 0;

    mbedtls_entropy_init(&entropy);
    mbedtls_ctr_drbg_init(&ctr_drbg);
    mbedtls_pk_init(&pk);

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    psa_status_t status = psa_crypto_init();
    if (status != PSA_SUCCESS) {
        mbedtls_fprintf(stderr, "Failed to initialize PSA Crypto implementation: %d\n",
                        (int) status);
        goto exit;
    }
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    if (argc != 3) {
        mbedtls_printf("usage: mbedtls_pk_sign <key_file> <filename>\n");

#if defined(_WIN32)
        mbedtls_printf("\n");
#endif

        goto exit;
    }

    mbedtls_printf("\n  . Seeding the random number generator...");
    fflush(stdout);

    if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
                                     (const unsigned char *) pers,
                                     strlen(pers))) != 0) {
        mbedtls_printf(" failed\n  ! mbedtls_ctr_drbg_seed returned -0x%04x\n",
                       (unsigned int) -ret);
        goto exit;
    }

    mbedtls_printf("\n  . Reading private key from '%s'", argv[1]);
    fflush(stdout);

    if ((ret = mbedtls_pk_parse_keyfile(&pk, argv[1], "")) != 0) {
        mbedtls_printf(" failed\n  ! Could not parse '%s'\n", argv[1]);
        goto exit;
    }

    /*
     * Compute the SHA-256 hash of the input file,
     * then calculate the signature of the hash.
     */
    mbedtls_printf("\n  . Generating the SHA-256 signature");
    fflush(stdout);

    if ((ret = mbedtls_md_file(
             mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
             argv[2], hash)) != 0) {
        mbedtls_printf(" failed\n  ! Could not open or read %s\n\n", argv[2]);
        goto exit;
    }

    if ((ret = mbedtls_pk_sign(&pk, MBEDTLS_MD_SHA256, hash, 0,
                               buf, sizeof(buf), &olen)) != 0) {
        mbedtls_printf(" failed\n  ! mbedtls_pk_sign returned -0x%04x\n", (unsigned int) -ret);
        goto exit;
    }

    /*
     * Write the signature into <filename>.sig
     */
    mbedtls_snprintf(filename, sizeof(filename), "%s.sig", argv[2]);

    if ((f = fopen(filename, "wb+")) == NULL) {
        mbedtls_printf(" failed\n  ! Could not create %s\n\n", filename);
        goto exit;
    }

    if (fwrite(buf, 1, olen, f) != olen) {
        mbedtls_printf("failed\n  ! fwrite failed\n\n");
        fclose(f);
        goto exit;
    }

    fclose(f);

    mbedtls_printf("\n  . Done (created \"%s\")\n\n", filename);

    exit_code = MBEDTLS_EXIT_SUCCESS;

exit:
    mbedtls_pk_free(&pk);
    mbedtls_ctr_drbg_free(&ctr_drbg);
    mbedtls_entropy_free(&entropy);
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    mbedtls_psa_crypto_free();
#endif /* MBEDTLS_USE_PSA_CRYPTO */

#if defined(MBEDTLS_ERROR_C)
    if (exit_code != MBEDTLS_EXIT_SUCCESS) {
        mbedtls_printf("Error code: %d", ret);
        /* mbedtls_strerror(ret, (char *) buf, sizeof(buf));
           mbedtls_printf("  !  Last error was: %s\n", buf); */
    }
#endif

    mbedtls_exit(exit_code);
}
#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C &&
          PSA_WANT_ALG_SHA_256 && MBEDTLS_PK_PARSE_C && MBEDTLS_FS_IO &&
          MBEDTLS_CTR_DRBG_C */