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/*-
* Copyright 2019-2021 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
*/
/*-
* Example of using EVP_MD_fetch and EVP_Digest* methods to calculate
* a digest of static buffers
* You can find SHA3 test vectors from NIST here:
* https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Algorithm-Validation-Program/documents/sha3/sha-3bytetestvectors.zip
* For example, contains these lines:
Len = 80
Msg = 1ca984dcc913344370cf
MD = 6915ea0eeffb99b9b246a0e34daf3947852684c3d618260119a22835659e4f23d4eb66a15d0affb8e93771578f5e8f25b7a5f2a55f511fb8b96325ba2cd14816
* use xxd convert the hex message string to binary input for BIO_f_md:
* echo "1ca984dcc913344370cf" | xxd -r -p | ./BIO_f_md
* and then verify the output matches MD above.
*/
#include <string.h>
#include <stdio.h>
#include <openssl/err.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
/*-
* This demonstration will show how to digest data using
* a BIO configured with a message digest
* A message digest name may be passed as an argument.
* The default digest is SHA3-512
*/
int main(int argc, char * argv[])
{
int ret = EXIT_FAILURE;
OSSL_LIB_CTX *library_context = NULL;
BIO *input = NULL;
BIO *bio_digest = NULL, *reading = NULL;
EVP_MD *md = NULL;
unsigned char buffer[512];
int digest_size;
char *digest_value = NULL;
int j;
input = BIO_new_fd( fileno(stdin), 1 );
if (input == NULL) {
fprintf(stderr, "BIO_new_fd() for stdin returned NULL\n");
goto cleanup;
}
library_context = OSSL_LIB_CTX_new();
if (library_context == NULL) {
fprintf(stderr, "OSSL_LIB_CTX_new() returned NULL\n");
goto cleanup;
}
/*
* Fetch a message digest by name
* The algorithm name is case insensitive.
* See providers(7) for details about algorithm fetching
*/
md = EVP_MD_fetch( library_context, "SHA3-512", NULL );
if (md == NULL) {
fprintf(stderr, "EVP_MD_fetch did not find SHA3-512.\n");
goto cleanup;
}
digest_size = EVP_MD_get_size(md);
if (digest_size <= 0) {
fprintf(stderr, "EVP_MD_get_size returned invalid size.\n");
goto cleanup;
}
digest_value = OPENSSL_malloc(digest_size);
if (digest_value == NULL) {
fprintf(stderr, "Can't allocate %lu bytes for the digest value.\n", (unsigned long)digest_size);
goto cleanup;
}
/* Make a bio that uses the digest */
bio_digest = BIO_new(BIO_f_md());
if (bio_digest == NULL) {
fprintf(stderr, "BIO_new(BIO_f_md()) returned NULL\n");
goto cleanup;
}
/* set our bio_digest BIO to digest data */
if (BIO_set_md(bio_digest,md) != 1) {
fprintf(stderr, "BIO_set_md failed.\n");
goto cleanup;
}
/*-
* We will use BIO chaining so that as we read, the digest gets updated
* See the man page for BIO_push
*/
reading = BIO_push(bio_digest, input);
while (BIO_read(reading, buffer, sizeof(buffer)) > 0)
;
/*-
* BIO_gets must be used to calculate the final
* digest value and then copy it to digest_value.
*/
if (BIO_gets(bio_digest, digest_value, digest_size) != digest_size) {
fprintf(stderr, "BIO_gets(bio_digest) failed\n");
goto cleanup;
}
for (j=0; j<digest_size; j++) {
fprintf(stdout, "%02x", (unsigned char)digest_value[j]);
}
fprintf(stdout, "\n");
ret = EXIT_SUCCESS;
cleanup:
if (ret != EXIT_SUCCESS)
ERR_print_errors_fp(stderr);
OPENSSL_free(digest_value);
BIO_free(input);
BIO_free(bio_digest);
EVP_MD_free(md);
OSSL_LIB_CTX_free(library_context);
return ret;
}
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