因为我的项目须要验证签名，这里不做签名，只验签间接上代码：
应用办法：openssl版本：1.0.2g 其余的自行验证编译：g++ x509.cpp -o x509 -lssl -lcrypto执行：./x509
#include <openssl/pem.h>#include <openssl/x509.h>#include <openssl/x509v3.h>#include <cstring>#include <iostream>// base64 编码char *base64_encode(const char *buffer, int length) { BIO *bmem = NULL; BIO *b64 = NULL; BUF_MEM *bptr; char *buff = NULL; b64 = BIO_new(BIO_f_base64()); BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL); bmem = BIO_new(BIO_s_mem()); b64 = BIO_push(b64, bmem); BIO_write(b64, buffer, length); BIO_flush(b64); BIO_get_mem_ptr(b64, &bptr); BIO_set_close(b64, BIO_NOCLOSE); buff = (char *)malloc(bptr->length + 1); memcpy(buff, bptr->data, bptr->length); buff[bptr->length] = 0; BIO_free_all(b64); return buff;}// base64 解码char *base64_decode(char *input, int length) { BIO *b64 = NULL; BIO *bmem = NULL; char *buffer = NULL; buffer = (char *)malloc(length); memset(buffer, 0, length); b64 = BIO_new(BIO_f_base64()); BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL); bmem = BIO_new_mem_buf(input, length); bmem = BIO_push(b64, bmem); BIO_read(bmem, buffer, length); BIO_free_all(bmem); return buffer;}int get_str_len(const char *in) { int num = 0; if(in == NULL) { return 0; } while (!((*(in + num) == NULL) && (*(in + num + 1) == NULL) \ && (*(in + num + 2) == NULL) && (*(in + num + 3) == NULL) \ && (*(in + num + 4) == NULL)&& (*(in + num + 5) == NULL) \ && (*(in + num + 6) == NULL)&& (*(in + num + 7) == NULL))) { num++; } return num;}static const char hex_table[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};// 字节转十六进制字符串std::string BytesToHexStr(const char* aInStr, int len){ std::string hex_str; for (int i = 0; i < len; ++i) { hex_str.append(&hex_table[(aInStr[i] & 0xF0) >> 4], 1); hex_str.append(&hex_table[aInStr[i] & 0xF], 1); } std::cout << hex_str << std::endl; return hex_str;}// 字符串截取char* substring(char* ch,int pos,int length) { // 定义字符指针 指向传递进来的ch地址 char *pch = ch; // 通过calloc来调配一个length长度的字符数组，返回的是字符指针。 char *subch = (char*)calloc(sizeof(char),length+1); int i; // 只有在C99下for循环中才能够申明变量，这里写在里面，进步兼容性。 pch = pch + pos; // 是pch指针指向pos地位。 for(i = 0; i < length; i++) { subch[i] = *(pch++); // 循环遍历赋值数组。 } subch[length]='\0'; // 加上字符串结束符。 return subch; // 返回调配的字符数组地址。} int ECDSA_WithSHA256_do_verify(const char *strx509, char *message, unsigned int messageLen, char *signBuf, unsigned int signLen) { EC_KEY * ec_key; EVP_MD_CTX md_ctx; int ret = -1; char *Sigbuff = NULL, *Signature = NULL, *r = NULL, *s = NULL; char dst_str[2][512+1]; unsigned char digest[EVP_MAX_MD_SIZE]; unsigned int digestLen = 0; BIO *bio_mem = BIO_new(BIO_s_mem()); BIO_puts(bio_mem, strx509); X509 * x509 = PEM_read_bio_X509(bio_mem, NULL, NULL, NULL); EVP_PKEY *pkey = X509_get_pubkey(x509); // 获取证书的公钥 if (pkey->type == EVP_PKEY_EC) { ec_key = EVP_PKEY_get1_EC_KEY(pkey); if (!ec_key) { printf("get EVP_PKEY_get1_EC_KEY fail \n"); } } EVP_PKEY_free(pkey); Sigbuff = base64_decode(message,messageLen); // base64解码后的验证数据 Signature = base64_decode(signBuf,signLen); // base64解码后的签名数据 printf("Sigbuff: %s\n", Sigbuff); printf("Signature: %s\n Signature len: %d\n EVP_MAX_MD_SIZE: %d\n", Signature,get_str_len(Signature), EVP_MAX_MD_SIZE); r = substring(Signature,0,get_str_len(Signature)/2); s = substring(Signature,get_str_len(Signature)/2,get_str_len(Signature)); std::string rSignatureInHex = BytesToHexStr(r,get_str_len(Signature)/2); std::string sSignatureInHex = BytesToHexStr(s,get_str_len(Signature)/2); free(r); free(s); EVP_MD_CTX_init(&md_ctx); if (!EVP_DigestInit(&md_ctx, EVP_sha256())) { printf("EVP_digest fail \n"); } if (!EVP_DigestUpdate(&md_ctx, (const void *)Sigbuff, get_str_len(Sigbuff))) { printf("EVP_DigestUpdate fail \n"); } if (!EVP_DigestFinal(&md_ctx, digest, &digestLen)) { printf("EVP_DigestFinal fail \n"); } free(Sigbuff); free(Signature); ECDSA_SIG *sig = (ECDSA_SIG *)malloc(sizeof(ECDSA_SIG)); strncpy(dst_str[0], rSignatureInHex.c_str(), 512); strncpy(dst_str[1], sSignatureInHex.c_str(), 512); printf("dst_str[0]: %s\n", &dst_str[0]); printf("dst_str[1]: %s\n", &dst_str[1]); sig->r = BN_new(); sig->s = BN_new(); BN_hex2bn(&(sig->r), dst_str[0]); //十六进制转二进制 BN_hex2bn(&(sig->s), dst_str[1]); /*do verify*/ ret = ECDSA_do_verify((const unsigned char*)digest, digestLen, sig, ec_key); if (ret == -1) { printf("ECDSA_verify failed\n"); } else if (ret == 0) { printf("ECDSA_verify incorrect signature\n"); } else { printf("ECDSA_verify ok\n"); } BN_free(sig->r); BN_free(sig->s); free(sig); if (ec_key) { EC_KEY_free(ec_key); ec_key = NULL; } BIO_free(bio_mem); X509_free(x509); return ret;}int main(int argc, char **argv){ OpenSSL_add_all_algorithms(); // 须要验证的数据的base64编码 char message[] = "hGpTaWduYXR1cmUxTaIESDSaQrDC0HKOASZAWQECpAQaZF2BgAYaYUOemQFiSVQ5AQOhAaRhdoGqYmRuAWJtYW1PUkctMTAwMDAxNjk5YnZwajExMTkzMDUwMDViZHRqMjAyMS0wNS0wNWJjb2JJVGJjaXgmMDFJVDVBMUM2NEYyREYwODQ3RjI5Rjc0MTA2MjA1OEFGQUUwIzFibXBsRVUvMS8yMS8xNTI5Ymlzdk1pbmlzdGVybyBkZWxsYSBTYWx1dGVic2QBYnRnaTg0MDUzOTAwNmNuYW2kY2ZudGdQQU5ESU5JYmZuZ1BBTkRJTkljZ250ZkFORFJFQWJnbmZBTkRSRUFjdmVyZTEuMC4wY2RvYmoxOTUyLTA5LTI4"; // 摘要签名数据的base64编码 char signBuf[] = "a0KNpWa23iFQue19IioU/jrUPd/Utoo9A4prMG9LvS3FCsNEHHAwoAUpO4/KIfLB6R1MiIakaIJo4lIBawvUOA=="; // 证书 std::string str = "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"; str.insert(0,"-----BEGIN CERTIFICATE-----" "\n"); str.append( "\n" "-----END CERTIFICATE-----" "\n"); int ret = ECDSA_WithSHA256_do_verify(str.c_str(), message, sizeof(message), signBuf, sizeof(signBuf)); printf("ECDSA_WithSHA256 ret = %d\n", ret);}/*应用办法：openssl版本：1.0.2g 其余的自行验证编译：g++ x509.cpp -o x509 -lssl -lcrypto执行：./x509*/