openssl3.2 - 官方demo学习 - pkey - EVP_PKEY_EC_keygen.c

概述

给定椭圆曲线名字, 产生上下文_evp_pkey_ctx
设置_evp_pkey_ctx的椭圆曲线参数(有默认参数, 不用特意设置, 给熟悉的人用), 不熟悉密码学的人, 只选椭圆曲线的名字就行
从_evp_pkey_ctx产生ec key;
打印 ec EVP_PKEY 的值(可以取出椭圆曲线的名字, 公钥, 私钥).

笔记

/*!
\file EVP_PKEY_EC_keygen.c
\note 
openssl3.2 - 官方demo学习 - pkey - EVP_PKEY_EC_keygen.c给定椭圆曲线名字, 产生上下文_evp_pkey_ctx
设置_evp_pkey_ctx的椭圆曲线参数(有默认参数, 不用特意设置, 给熟悉的人用), 不熟悉密码学的人, 只选椭圆曲线的名字就行
从_evp_pkey_ctx产生ec key;
打印 ec EVP_PKEY 的值(可以取出椭圆曲线的名字, 公钥, 私钥).
*//*-* Copyright 2021-2023 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 showing how to generate an EC key and extract values from the* generated key.*/#include <string.h>
#include <stdio.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/core_names.h>#include "my_openSSL_lib.h"static int get_key_values(EVP_PKEY* pkey);/** The following code shows how to generate an EC key from a curve name* with additional parameters. If only the curve name is required then the* simple helper can be used instead i.e. Either* pkey = EVP_EC_gen(curvename); OR* pkey = EVP_PKEY_Q_keygen(libctx, propq, "EC", curvename);*/
static EVP_PKEY* do_ec_keygen(void)
{/** The libctx and propq can be set if required, they are included here* to show how they are passed to EVP_PKEY_CTX_new_from_name().*/OSSL_LIB_CTX* _ossl_lib_ctx = NULL;const char* propq = NULL;EVP_PKEY* key = NULL;OSSL_PARAM _ossl_param[3];EVP_PKEY_CTX* _evp_pkey_ctx = NULL;const char* curvename = "P-256"; /*! 椭圆曲线的名字 */int use_cofactordh = 1;_evp_pkey_ctx = EVP_PKEY_CTX_new_from_name(_ossl_lib_ctx, "EC", propq);if (_evp_pkey_ctx == NULL) {fprintf(stderr, "EVP_PKEY_CTX_new_from_name() failed\n");goto cleanup;}if (EVP_PKEY_keygen_init(_evp_pkey_ctx) <= 0) {fprintf(stderr, "EVP_PKEY_keygen_init() failed\n");goto cleanup;}_ossl_param[0] = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_GROUP_NAME,(char*)curvename, 0);/** This is an optional parameter.* For many curves where the cofactor is 1, setting this has no effect.*/_ossl_param[1] = OSSL_PARAM_construct_int(OSSL_PKEY_PARAM_USE_COFACTOR_ECDH,&use_cofactordh);_ossl_param[2] = OSSL_PARAM_construct_end();if (!EVP_PKEY_CTX_set_params(_evp_pkey_ctx, _ossl_param)) {fprintf(stderr, "EVP_PKEY_CTX_set_params() failed\n");goto cleanup;}fprintf(stdout, "Generating EC key\n\n");if (EVP_PKEY_generate(_evp_pkey_ctx, &key) <= 0) {fprintf(stderr, "EVP_PKEY_generate() failed\n");goto cleanup;}
cleanup:EVP_PKEY_CTX_free(_evp_pkey_ctx);return key;
}/** The following code shows how retrieve key data from the generated* EC key. See doc/man7/EVP_PKEY-EC.pod for more information.** EVP_PKEY_print_private() could also be used to display the values.*/
static int get_key_values(EVP_PKEY* pkey)
{int ret = 0;char out_curvename[80];unsigned char out_pubkey[80];unsigned char out_privkey[80];BIGNUM* out_priv = NULL;size_t out_pubkey_len, out_privkey_len = 0;if (!EVP_PKEY_get_utf8_string_param(pkey, OSSL_PKEY_PARAM_GROUP_NAME,out_curvename, sizeof(out_curvename),NULL)) {fprintf(stderr, "Failed to get curve name\n");goto cleanup;}if (!EVP_PKEY_get_octet_string_param(pkey, OSSL_PKEY_PARAM_PUB_KEY,out_pubkey, sizeof(out_pubkey),&out_pubkey_len)) {fprintf(stderr, "Failed to get public key\n");goto cleanup;}if (!EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_PRIV_KEY, &out_priv)) {fprintf(stderr, "Failed to get private key\n");goto cleanup;}out_privkey_len = BN_bn2bin(out_priv, out_privkey);if (out_privkey_len <= 0 || out_privkey_len > sizeof(out_privkey)) {fprintf(stderr, "BN_bn2bin failed\n");goto cleanup;}fprintf(stdout, "Curve name: %s\n", out_curvename);fprintf(stdout, "Public key:\n");BIO_dump_indent_fp(stdout, out_pubkey, (int)out_pubkey_len, 2);fprintf(stdout, "Private Key:\n");BIO_dump_indent_fp(stdout, out_privkey, (int)out_privkey_len, 2);ret = 1;
cleanup:/* Zeroize the private key data when we free it */BN_clear_free(out_priv);return ret;
}int main(void)
{int ret = EXIT_FAILURE;EVP_PKEY* _evp_pkey_ec;_evp_pkey_ec = do_ec_keygen();if (_evp_pkey_ec == NULL)goto cleanup;if (!get_key_values(_evp_pkey_ec))goto cleanup;/** At this point we can write out the generated key using* i2d_PrivateKey() and i2d_PublicKey() if required.*/ret = EXIT_SUCCESS;
cleanup:if (ret != EXIT_SUCCESS)ERR_print_errors_fp(stderr);EVP_PKEY_free(_evp_pkey_ec);return ret;
}

END