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 = 80Msg = 1ca984dcc913344370cfMD = 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