1.直接上源码：
#include <stdio.h> #include <string.h> #include <openssl/ecdsa.h> #include <openssl/pem.h> #include <openssl/err.h> // 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; } //公钥验证签名 int my_verify(const char *input, int input_len, ECDSA_SIG *signret, const char *pub_key_fn) { EC_KEY *p_dsa = NULL; FILE *file = NULL; int ret = 0; unsigned char digest[EVP_MAX_MD_SIZE]; unsigned int digest_len = 0; EVP_MD_CTX md_ctx; if((file = fopen(pub_key_fn, "rb")) == NULL) { ret = -1; return ret; } if((p_dsa = PEM_read_EC_PUBKEY(file, NULL,NULL,NULL )) == NULL) { // 获取公钥的ec key ret = -2; fclose(file); return ret; } fclose(file); EVP_MD_CTX_init(&md_ctx); if (!EVP_DigestInit(&md_ctx, EVP_sha256())) { printf("EVP_digest fail \n"); return -1; } if (!EVP_DigestUpdate(&md_ctx, (const void *)input, input_len)) { printf("EVP_DigestUpdate fail \n"); return -1; } if (!EVP_DigestFinal(&md_ctx, digest, &digest_len)) { // 待签名消息用sha256生成256比特的签名摘要 printf("EVP_DigestFinal fail \n"); return -1; } printf("verify digest: %s\n", digest); ret = ECDSA_do_verify(digest, digest_len, signret, p_dsa); // 对签名摘要进行验签得到结果 if (ret == -1) { ret = -3; printf("ECDSA_verify err!\n"); EC_KEY_free(p_dsa); return ret; } else if (ret == 0) { ret = -3; printf("ECDSA_verify err incorrect signature!\n"); EC_KEY_free(p_dsa); return ret; } else { printf("ECDSA_verify ok\n"); } printf("verify is ok!\n"); EC_KEY_free(p_dsa); return 0; } //私钥签名 int my_sign(const char *input, int input_len, const char *pri_key_fn) { EC_KEY *p_dsa = NULL; ECDSA_SIG *s; FILE *file = NULL; unsigned char *data[2]; int nid; int signlen = 0; int i = 0; int ret = 0; unsigned char digest[EVP_MAX_MD_SIZE]; unsigned int digest_len = 0; EVP_MD_CTX md_ctx; memset(data, 0x00, sizeof(data)); nid = 0; file = fopen(pri_key_fn, "rb"); if(!file) { ret = -1; return ret; } if((p_dsa = PEM_read_ECPrivateKey(file, NULL, NULL, NULL)) == NULL) { // 获取私钥的ec key ret = -2; fclose(file); return ret; } fclose(file); EVP_MD_CTX_init(&md_ctx); if (!EVP_DigestInit(&md_ctx, EVP_sha256())) { printf("EVP_digest fail \n"); return -1; } if (!EVP_DigestUpdate(&md_ctx, (const void *)input, input_len)) { printf("EVP_DigestUpdate fail \n"); return -1; } if (!EVP_DigestFinal(&md_ctx, digest, &digest_len)) { // 待签名消息用sha256生成256比特的签名摘要 printf("EVP_DigestFinal fail \n"); return -1; } printf("sign digest: %s\n", digest); s = ECDSA_do_sign(digest, digest_len, p_dsa); // 对签名摘要进行签名得到签名数据s if(s == NULL) { ret = -3; EC_KEY_free(p_dsa); return ret; } data[0] = BN_bn2hex(s->r); //二进制转十六进制 data[1] = BN_bn2hex(s->s); EC_KEY_free(p_dsa); ECDSA_SIG_free(s); printf("%s\n", data[0]); printf("%s\n", data[1]); free(data[0]); free(data[1]); return 0; } int main(int argc, char**argv) { char src[512+1]; char dst_str[2][512+1]; int src_len; int ret; FILE *f; memset(src, 0x00, sizeof(src)); memset(dst_str, 0x00, sizeof(dst_str)); if(argv[1][0] == 's') { strcpy(src, "hello world"); // 待签名消息 src_len = strlen(src) ; ret = my_sign(src, src_len, argv[2]); if(ret) { fprintf(stderr, "Error\n"); } } else { ECDSA_SIG *s = (ECDSA_SIG *)malloc(sizeof(ECDSA_SIG)); strcpy(src, "hello world"); // 需要验证的签名消息 strncpy(dst_str[0], argv[2], 512); strncpy(dst_str[1], argv[3], 512); src_len = strlen(src); s->r = BN_new(); s->s = BN_new(); BN_hex2bn(&(s->r), dst_str[0]); //十六进制转二进制 BN_hex2bn(&(s->s), dst_str[1]); ret = my_verify(src, src_len, s, argv[1]); if(ret) { fprintf(stderr, "Error\n"); } BN_free(s->r); BN_free(s->s); free(s); } return 0; }
2.编译环境
openssl版本为1.0.2g，openssl version查看openssl的版本，其他版本自行验证
base的编解码代码也有，这里demo暂不使用
3.编译
gcc ecdsa.c -o ecdsa -lssl -lcrypto
4.生成私钥和公钥
openssl ecparam -genkey -name prime256v1 -out eccpri256.key openssl ec -in eccpri256.key -pubout -out eccpri256.pem
5.运行结果
root@ubuntu:/home/workspace/test/demo_sign# ./ecdsa s eccpri256.key sign digest: ¹M'¹M¥.Rؚ}«尣zSΩ E948080F0496BEAF2303A184BF9F67491AB95920BD3951DBABA36813768273DF 568224ECBA9A83161E1494DAB02884B123A376DE57A9A7BA4F018A5BB9E38404 root@ubuntu:/home/workspace/test/demo_sign# ./ecdsa eccpri256.pem E948080F0496BEAF2303A184BF9F67491AB95920BD3951DBABA36813768273DF 568224ECBA9A83161E1494DAB02884B123A376DE57A9A7BA4F018A5BB9E38404 verify digest: ¹M'¹M¥.Rؚ}«尣zSΩ3*fO@ ECDSA_verify ok verify is ok!
