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      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 }
    130