1 /*-
2 * Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 /*-
11 * Example of using EVP_MD_fetch and EVP_Digest* methods to calculate
12 * a digest of static buffers
13 * You can find SHA3 test vectors from NIST here:
14 * https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Algorithm-Validation-Program/documents/sha3/sha-3bytetestvectors.zip
15 * For example, contains these lines:
16 Len = 80
17 Msg = 1ca984dcc913344370cf
18 MD = 6915ea0eeffb99b9b246a0e34daf3947852684c3d618260119a22835659e4f23d4eb66a15d0affb8e93771578f5e8f25b7a5f2a55f511fb8b96325ba2cd14816
19 * use xxd convert the hex message string to binary input for BIO_f_md:
20 * echo "1ca984dcc913344370cf" | xxd -r -p | ./BIO_f_md
21 * and then verify the output matches MD above.
22 */
23
24 #include <string.h>
25 #include <stdio.h>
26 #include <openssl/err.h>
27 #include <openssl/bio.h>
28 #include <openssl/evp.h>
29
30 /*-
31 * This demonstration will show how to digest data using
32 * a BIO configured with a message digest
33 * A message digest name may be passed as an argument.
34 * The default digest is SHA3-512
35 */
36
main(int argc,char * argv[])37 int main(int argc, char * argv[])
38 {
39 int result = 1;
40 OSSL_LIB_CTX *library_context = NULL;
41 BIO *input = NULL;
42 BIO *bio_digest = NULL;
43 EVP_MD *md = NULL;
44 unsigned char buffer[512];
45 size_t readct, writect;
46 size_t digest_size;
47 char *digest_value=NULL;
48 int j;
49
50 input = BIO_new_fd(fileno(stdin), 1);
51 if (input == NULL) {
52 fprintf(stderr, "BIO_new_fd() for stdin returned NULL\n");
53 goto cleanup;
54 }
55 library_context = OSSL_LIB_CTX_new();
56 if (library_context == NULL) {
57 fprintf(stderr, "OSSL_LIB_CTX_new() returned NULL\n");
58 goto cleanup;
59 }
60
61 /*
62 * Fetch a message digest by name
63 * The algorithm name is case insensitive.
64 * See providers(7) for details about algorithm fetching
65 */
66 md = EVP_MD_fetch(library_context, "SHA3-512", NULL);
67 if (md == NULL) {
68 fprintf(stderr, "EVP_MD_fetch did not find SHA3-512.\n");
69 goto cleanup;
70 }
71 digest_size = EVP_MD_get_size(md);
72 digest_value = OPENSSL_malloc(digest_size);
73 if (digest_value == NULL) {
74 fprintf(stderr, "Can't allocate %lu bytes for the digest value.\n", (unsigned long)digest_size);
75 goto cleanup;
76 }
77 /* Make a bio that uses the digest */
78 bio_digest = BIO_new(BIO_f_md());
79 if (bio_digest == NULL) {
80 fprintf(stderr, "BIO_new(BIO_f_md()) returned NULL\n");
81 goto cleanup;
82 }
83 /* set our bio_digest BIO to digest data */
84 if (BIO_set_md(bio_digest, md) != 1) {
85 fprintf(stderr, "BIO_set_md failed.\n");
86 goto cleanup;
87 }
88 /*-
89 * We will use BIO chaining so that as we read, the digest gets updated
90 * See the man page for BIO_push
91 */
92 BIO *reading = BIO_push(bio_digest, input);
93
94 while (BIO_read(reading, buffer, sizeof(buffer)) > 0)
95 ;
96
97 /*-
98 * BIO_gets must be used to calculate the final
99 * digest value and then copy it to digest_value.
100 */
101 if (BIO_gets(bio_digest, digest_value, digest_size) != digest_size) {
102 fprintf(stderr, "BIO_gets(bio_digest) failed\n");
103 goto cleanup;
104 }
105 for (j = 0; j < digest_size; j++) {
106 fprintf(stdout, "%02x", (unsigned char)digest_value[j]);
107 }
108 fprintf(stdout, "\n");
109 result = 0;
110
111 cleanup:
112 if (result != 0)
113 ERR_print_errors_fp(stderr);
114
115 OPENSSL_free(digest_value);
116 BIO_free(input);
117 BIO_free(bio_digest);
118 EVP_MD_free(md);
119 OSSL_LIB_CTX_free(library_context);
120
121 return result;
122 }
123
