openssl3.2 - 官方demo学习 - digest - EVP_MD_stdin.c

openssl3.2 - 官方demo学习 - digest - EVP_MD_stdin.c

概述

使用 SHA3-512 对stdin输入做摘要, 并输出摘要值.

笔记

/*!
\file EVP_MD_stdin.c
\note openssl3.2 - 官方demo学习 - digest - EVP_MD_stdin.c
使用 SHA3-512 对stdin输入做摘要, 并输出摘要值.
*/

/*-
 * Copyright 2019-2023 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
 */

 /*-
  * Example of using EVP_MD_fetch and EVP_Digest* methods to calculate
  * a digest of static buffers
  * You can find SHA3 test vectors from NIST here:
  * https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Algorithm-Validation-Program/documents/sha3/sha-3bytetestvectors.zip
  * For example, contains these lines:
	 Len = 80
	 Msg = 1ca984dcc913344370cf
	 MD = 6915ea0eeffb99b9b246a0e34daf3947852684c3d618260119a22835659e4f23d4eb66a15d0affb8e93771578f5e8f25b7a5f2a55f511fb8b96325ba2cd14816
  * use xxd convert the hex message string to binary input for EVP_MD_stdin:
  * echo "1ca984dcc913344370cf" | xxd -r -p | ./EVP_MD_stdin
  * and then verify the output matches MD above.
  */

#include <string.h>
#include <stdio.h>
#include <openssl/err.h>
#include <openssl/evp.h>

#include "my_openSSL_lib.h"

  /*-
   * This demonstration will show how to digest data using
   * a BIO created to read from stdin
   */

int demonstrate_digest(BIO* bio_input)
{
	OSSL_LIB_CTX* _ossl_lib_ctx = NULL;
	int ret = 0;
	const char* _psz_option_properties = NULL;
	EVP_MD* _evp_md_message_digest = NULL;
	EVP_MD_CTX* _evp_md_ctx_digest_context = NULL;
	unsigned int digest_length;
	unsigned char* _psz_digest_value = NULL;
	unsigned char buffer[512];
	int i;

	_ossl_lib_ctx = OSSL_LIB_CTX_new();
	if (_ossl_lib_ctx == NULL) {
		fprintf(stderr, "OSSL_LIB_CTX_new() returned NULL\n");
		goto cleanup;
	}

	/*
	 * Fetch a message digest by name
	 * The algorithm name is case insensitive.
	 * See providers(7) for details about algorithm fetching
	 */
	_evp_md_message_digest = EVP_MD_fetch(_ossl_lib_ctx,
		"SHA3-512", _psz_option_properties);
	if (_evp_md_message_digest == NULL) {
		fprintf(stderr, "EVP_MD_fetch could not find SHA3-512.");
		ERR_print_errors_fp(stderr);
		OSSL_LIB_CTX_free(_ossl_lib_ctx);
		return 0;
	}
	/* Determine the length of the fetched digest type */
	digest_length = EVP_MD_get_size(_evp_md_message_digest);
	if (digest_length <= 0) {
		fprintf(stderr, "EVP_MD_get_size returned invalid size.\n");
		goto cleanup;
	}

	_psz_digest_value = OPENSSL_malloc(digest_length);
	if (_psz_digest_value == NULL) {
		fprintf(stderr, "No memory.\n");
		goto cleanup;
	}
	/*
	 * Make a message digest context to hold temporary state
	 * during digest creation
	 */
	_evp_md_ctx_digest_context = EVP_MD_CTX_new();
	if (_evp_md_ctx_digest_context == NULL) {
		fprintf(stderr, "EVP_MD_CTX_new failed.\n");
		ERR_print_errors_fp(stderr);
		goto cleanup;
	}
	/*
	 * Initialize the message digest context to use the fetched
	 * digest provider
	 */
	if (EVP_DigestInit(_evp_md_ctx_digest_context, _evp_md_message_digest) != 1) {
		fprintf(stderr, "EVP_DigestInit failed.\n");
		ERR_print_errors_fp(stderr);
		goto cleanup;
	}
	while ((i = BIO_read(bio_input, buffer, sizeof(buffer))) > 0) {
		if (EVP_DigestUpdate(_evp_md_ctx_digest_context, buffer, i) != 1) {
			fprintf(stderr, "EVP_DigestUpdate() failed.\n");
			goto cleanup;
		}

		break; /*! 只处理一次用户输入就拉到了, 实际应用中可以多次调用EVP_DigestUpdate  */
	}
	if (EVP_DigestFinal(_evp_md_ctx_digest_context, _psz_digest_value, &digest_length) != 1) {
		fprintf(stderr, "EVP_DigestFinal() failed.\n");
		goto cleanup;
	}
	ret = 1;
	for (i = 0; i < (int)digest_length; i++) {
		fprintf(stdout, "%02x", _psz_digest_value[i]);
	}
	fprintf(stdout, "\n");

cleanup:
	if (ret != 1)
		ERR_print_errors_fp(stderr);
	/* OpenSSL free functions will ignore NULL arguments */
	EVP_MD_CTX_free(_evp_md_ctx_digest_context);
	OPENSSL_free(_psz_digest_value);
	EVP_MD_free(_evp_md_message_digest);

	OSSL_LIB_CTX_free(_ossl_lib_ctx);
	return ret;
}

int main(void)
{
	int ret = EXIT_FAILURE;
	BIO* input = BIO_new_fd(fileno(stdin), 1);

	if (input != NULL) {
		ret = (demonstrate_digest(input) ? EXIT_SUCCESS : EXIT_FAILURE);
		BIO_free(input);
	}
	if (ret != EXIT_SUCCESS)
		ERR_print_errors_fp(stderr);
	return ret;
}

END