mirror of
https://github.com/openssl/openssl.git
synced 2024-12-15 06:01:37 +08:00
09ff84bd27
The demo code is quite often block copied for new demos, so this PR changes demos to use EXIT_SUCCESS & EXIT_FAILURE instead of using 0 and 1. Internal functions use the normal notation of 0 = error, 1 = success, but the value returned by main() must use EXIT_SUCCESS and EXIT_FAILURE. Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from https://github.com/openssl/openssl/pull/20545)
133 lines
3.9 KiB
C
133 lines
3.9 KiB
C
/*-
|
|
* Copyright 2022 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
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <openssl/err.h>
|
|
#include <openssl/evp.h>
|
|
#include <openssl/core_names.h>
|
|
|
|
/*
|
|
* Example of using an extendable-output hash function (XOF). A XOF is a hash
|
|
* function with configurable output length and which can generate an
|
|
* arbitrarily large output.
|
|
*
|
|
* This example uses SHAKE256, an extendable output variant of SHA3 (Keccak).
|
|
*
|
|
* To generate different output lengths, you can pass a single integer argument
|
|
* on the command line, which is the output size in bytes. By default, a 20-byte
|
|
* output is generated and (for this length only) a known answer test is
|
|
* performed.
|
|
*/
|
|
|
|
/* Our input to the XOF hash function. */
|
|
const char message[] = "This is a test message.";
|
|
|
|
/* Expected output when an output length of 20 bytes is used. */
|
|
static const char known_answer[] = {
|
|
0x52, 0x97, 0x93, 0x78, 0x27, 0x58, 0x7d, 0x62,
|
|
0x8b, 0x00, 0x25, 0xb5, 0xec, 0x39, 0x5e, 0x2d,
|
|
0x7f, 0x3e, 0xd4, 0x19
|
|
};
|
|
|
|
/*
|
|
* A property query used for selecting the SHAKE256 implementation.
|
|
*/
|
|
static const char *propq = NULL;
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
int ret = EXIT_FAILURE;
|
|
OSSL_LIB_CTX *libctx = NULL;
|
|
EVP_MD *md = NULL;
|
|
EVP_MD_CTX *ctx = NULL;
|
|
unsigned int digest_len = 20;
|
|
int digest_len_i;
|
|
unsigned char *digest = NULL;
|
|
|
|
/* Allow digest length to be changed for demonstration purposes. */
|
|
if (argc > 1) {
|
|
digest_len_i = atoi(argv[1]);
|
|
if (digest_len_i <= 0) {
|
|
fprintf(stderr, "Specify a non-negative digest length\n");
|
|
goto end;
|
|
}
|
|
|
|
digest_len = (unsigned int)digest_len_i;
|
|
}
|
|
|
|
/*
|
|
* Retrieve desired algorithm. This must be a hash algorithm which supports
|
|
* XOF.
|
|
*/
|
|
md = EVP_MD_fetch(libctx, "SHAKE256", propq);
|
|
if (md == NULL) {
|
|
fprintf(stderr, "Failed to retrieve SHAKE256 algorithm\n");
|
|
goto end;
|
|
}
|
|
|
|
/* Create context. */
|
|
ctx = EVP_MD_CTX_new();
|
|
if (ctx == NULL) {
|
|
fprintf(stderr, "Failed to create digest context\n");
|
|
goto end;
|
|
}
|
|
|
|
/* Initialize digest context. */
|
|
if (EVP_DigestInit(ctx, md) == 0) {
|
|
fprintf(stderr, "Failed to initialize digest\n");
|
|
goto end;
|
|
}
|
|
|
|
/*
|
|
* Feed our message into the digest function.
|
|
* This may be called multiple times.
|
|
*/
|
|
if (EVP_DigestUpdate(ctx, message, sizeof(message)) == 0) {
|
|
fprintf(stderr, "Failed to hash input message\n");
|
|
goto end;
|
|
}
|
|
|
|
/* Allocate enough memory for our digest length. */
|
|
digest = OPENSSL_malloc(digest_len);
|
|
if (digest == NULL) {
|
|
fprintf(stderr, "Failed to allocate memory for digest\n");
|
|
goto end;
|
|
}
|
|
|
|
/* Get computed digest. The digest will be of whatever length we specify. */
|
|
if (EVP_DigestFinalXOF(ctx, digest, digest_len) == 0) {
|
|
fprintf(stderr, "Failed to finalize hash\n");
|
|
goto end;
|
|
}
|
|
|
|
printf("Output digest:\n");
|
|
BIO_dump_indent_fp(stdout, digest, digest_len, 2);
|
|
|
|
/* If digest length is 20 bytes, check it matches our known answer. */
|
|
if (digest_len == 20) {
|
|
/*
|
|
* Always use a constant-time function such as CRYPTO_memcmp
|
|
* when comparing cryptographic values. Do not use memcmp(3).
|
|
*/
|
|
if (CRYPTO_memcmp(digest, known_answer, sizeof(known_answer)) != 0) {
|
|
fprintf(stderr, "Output does not match expected result\n");
|
|
goto end;
|
|
}
|
|
}
|
|
|
|
ret = EXIT_SUCCESS;
|
|
end:
|
|
OPENSSL_free(digest);
|
|
EVP_MD_CTX_free(ctx);
|
|
EVP_MD_free(md);
|
|
OSSL_LIB_CTX_free(libctx);
|
|
return ret;
|
|
}
|