demos/mac/siphash.c

   1 /*
   2  * Copyright 2021-2022 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
  45 int main(int argc, char **argv)
  46 {
  47     int rv = 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     rv = EXIT_SUCCESS;
 122 end:
 123     EVP_MAC_CTX_free(mctx);
 124     EVP_MAC_free(mac);
 125     OSSL_LIB_CTX_free(library_context);
 126     if (rv != EXIT_SUCCESS)
 127         ERR_print_errors_fp(stderr);
 128     return rv;
 129 }