xref: /openssl/demos/mac/siphash.c (revision da1c088f)
1 /*
2  * Copyright 2021-2023 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 #include <stdio.h>
11 #include <stdlib.h>
12 #include <openssl/core_names.h>
13 #include <openssl/evp.h>
14 #include <openssl/params.h>
15 #include <openssl/err.h>
16 
17 /*
18  * Taken from the test vector from the paper "SipHash: a fast short-input PRF".
19  * https://www.aumasson.jp/siphash/siphash.pdf
20  */
21 
22 /*
23  * Hard coding the key into an application is very bad.
24  * It is done here solely for educational purposes.
25  */
26 static unsigned char key[] = {
27     0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
28     0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f
29 };
30 
31 static unsigned char data[] = {
32     0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
33     0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e
34 };
35 
36 static const unsigned char expected_output[] = {
37     0xe5, 0x45, 0xbe, 0x49, 0x61, 0xca, 0x29, 0xa1
38 };
39 
40 /*
41  * A property query used for selecting the SIPHASH implementation.
42  */
43 static char *propq = NULL;
44 
main(int argc,char ** argv)45 int main(int argc, char **argv)
46 {
47     int ret = EXIT_FAILURE;
48     EVP_MAC *mac = NULL;
49     EVP_MAC_CTX *mctx = NULL;
50     unsigned char out[8];
51     OSSL_PARAM params[4], *p = params;
52     OSSL_LIB_CTX *library_context = NULL;
53     unsigned int digest_len = 8, c_rounds = 2, d_rounds = 4;
54     size_t out_len = 0;
55 
56     library_context = OSSL_LIB_CTX_new();
57     if (library_context == NULL) {
58         fprintf(stderr, "OSSL_LIB_CTX_new() returned NULL\n");
59         goto end;
60     }
61 
62     /* Fetch the SipHash implementation */
63     mac = EVP_MAC_fetch(library_context, "SIPHASH", propq);
64     if (mac == NULL) {
65         fprintf(stderr, "EVP_MAC_fetch() returned NULL\n");
66         goto end;
67     }
68 
69     /* Create a context for the SipHash operation */
70     mctx = EVP_MAC_CTX_new(mac);
71     if (mctx == NULL) {
72         fprintf(stderr, "EVP_MAC_CTX_new() returned NULL\n");
73         goto end;
74     }
75 
76     /* SipHash can support either 8 or 16-byte digests. */
77     *p++ = OSSL_PARAM_construct_uint(OSSL_MAC_PARAM_SIZE, &digest_len);
78 
79     /*
80      * The number of C-rounds and D-rounds is configurable. Standard SipHash
81      * uses values of 2 and 4 respectively. The following lines are unnecessary
82      * as they set the default, but demonstrate how to change these values.
83      */
84     *p++ = OSSL_PARAM_construct_uint(OSSL_MAC_PARAM_C_ROUNDS, &c_rounds);
85     *p++ = OSSL_PARAM_construct_uint(OSSL_MAC_PARAM_D_ROUNDS, &d_rounds);
86 
87     *p = OSSL_PARAM_construct_end();
88 
89     /* Initialise the SIPHASH operation */
90     if (!EVP_MAC_init(mctx, key, sizeof(key), params)) {
91         fprintf(stderr, "EVP_MAC_init() failed\n");
92         goto end;
93     }
94 
95     /* Make one or more calls to process the data to be authenticated */
96     if (!EVP_MAC_update(mctx, data, sizeof(data))) {
97         fprintf(stderr, "EVP_MAC_update() failed\n");
98         goto end;
99     }
100 
101     /* Make one call to the final to get the MAC */
102     if (!EVP_MAC_final(mctx, out, &out_len, sizeof(out))) {
103         fprintf(stderr, "EVP_MAC_final() failed\n");
104         goto end;
105     }
106 
107     printf("Generated MAC:\n");
108     BIO_dump_indent_fp(stdout, out, out_len, 2);
109     putchar('\n');
110 
111     if (out_len != sizeof(expected_output)) {
112         fprintf(stderr, "Generated MAC has an unexpected length\n");
113         goto end;
114     }
115 
116     if (CRYPTO_memcmp(expected_output, out, sizeof(expected_output)) != 0) {
117         fprintf(stderr, "Generated MAC does not match expected value\n");
118         goto end;
119     }
120 
121     ret = EXIT_SUCCESS;
122 end:
123     EVP_MAC_CTX_free(mctx);
124     EVP_MAC_free(mac);
125     OSSL_LIB_CTX_free(library_context);
126     if (ret != EXIT_SUCCESS)
127         ERR_print_errors_fp(stderr);
128     return ret;
129 }
130