使用visual studio调用 My_GenKeyPair 产生非对称密钥对； 调用 SM2Sig 进行签名，pbUserID=NULL； 再调用 SM2VerifySig 验证签名并详细编写My_GenKeyPair,SM2Sig,SM2VerifySig函数代码

下面是使用 Visual Studio 编写 My_GenKeyPair、SM2Sig 和 SM2VerifySig 函数的代码。

My_GenKeyPair 函数：

#include <openssl/ec.h>
#include <openssl/obj_mac.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>

#define KEY_LENGTH 1024

int My_GenKeyPair(char *pubkeyfile, char *privkeyfile)
{
    int ret = 0;
    RSA *r = NULL;
    BIGNUM *bne = NULL;
    BIO *bp_public = NULL, *bp_private = NULL;

    int bits = KEY_LENGTH;
    unsigned long e = RSA_F4;

    // 生成 RSA 密钥对
    bne = BN_new();
    ret = BN_set_word(bne, e);
    if (ret != 1) {
        goto finish;
    }

    r = RSA_new();
    ret = RSA_generate_key_ex(r, bits, bne, NULL);
    if (ret != 1) {
        goto finish;
    }

    // 将密钥对写入文件
    bp_public = BIO_new_file(pubkeyfile, "w+");
    ret = PEM_write_bio_RSAPublicKey(bp_public, r);
    if (ret != 1) {
        goto finish;
    }

    bp_private = BIO_new_file(privkeyfile, "w+");
    ret = PEM_write_bio_RSAPrivateKey(bp_private, r, NULL, NULL, 0, NULL, NULL);
    if (ret != 1) {
        goto finish;
    }

finish:
    if (r) {
        RSA_free(r);
    }
    if (bne) {
        BN_free(bne);
    }
    if (bp_public) {
        BIO_free_all(bp_public);
    }
    if (bp_private) {
        BIO_free_all(bp_private);
    }

    return ret;
}

SM2Sig 函数：

#include <openssl/bn.h>
#include <openssl/ec.h>
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <openssl/sm2.h>

int SM2Sig(const unsigned char *msg, size_t msglen, const char *privkeyfile, unsigned char *sig, size_t *siglen)
{
    int ret = 0;
    EC_KEY *ec_key = NULL;
    EVP_MD_CTX *md_ctx = NULL;
    unsigned char dgst[32];
    size_t dgstlen;
    const EVP_MD *md;
    BIGNUM *k = NULL;
    EC_POINT *P = NULL;

    // 读取私钥
    ec_key = EC_KEY_new_by_curve_name(NID_sm2);
    if (!ec_key) {
        goto finish;
    }

    FILE *fp = fopen(privkeyfile, "r");
    if (!fp) {
        goto finish;
    }

    PEM_read_ECPrivateKey(fp, &ec_key, NULL, NULL);
    fclose(fp);
    fp = NULL;

    // 计算消息摘要
    md = EVP_sm3();
    md_ctx = EVP_MD_CTX_new();
    EVP_DigestInit_ex(md_ctx, md, NULL);
    EVP_DigestUpdate(md_ctx, msg, msglen);
    EVP_DigestFinal_ex(md_ctx, dgst, &dgstlen);
    EVP_MD_CTX_free(md_ctx);
    md_ctx = NULL;

    // 生成随机数 k
    k = BN_new();
    ret = BN_rand_range(k, EC_GROUP_order(EC_KEY_get0_group(ec_key)));
    if (ret != 1) {
        goto finish;
    }

    // 计算椭圆曲线点 P = [k]G
    P = EC_POINT_new(EC_KEY_get0_group(ec_key));
    ret = EC_POINT_mul(EC_KEY_get0_group(ec_key), P, k, NULL, NULL, NULL);
    if (ret != 1) {
        goto finish;
    }

    // 计算 r = (e + x1) mod n
    BIGNUM *r = BN_new();
    const EC_POINT *pubkey = EC_KEY_get0_public_key(ec_key);
    EC_POINT_get_affine_coordinates(EC_KEY_get0_group(ec_key), pubkey, r, NULL, NULL);
    BN_add(r, r, dgst);
    BN_mod(r, r, EC_GROUP_order(EC_KEY_get0_group(ec_key)), NULL);

    // 计算 s = ((1 + dA)^-1 * (k - r * dA)) mod n
    BIGNUM *s = BN_new();
    BIGNUM *dA = BN_new();
    const BIGNUM *privkey = EC_KEY_get0_private_key(ec_key);
    BN_copy(dA, privkey);
    BN_mod_add(dA, dA, EC_GROUP_order(EC_KEY_get0_group(ec_key)), EC_GROUP_order(EC_KEY_get0_group(ec_key)), NULL);
    BN_add_word(dA, 1);
    BN_mod_inverse(dA, dA, EC_GROUP_order(EC_KEY_get0_group(ec_key)), NULL);
    BN_mul(s, r, privkey, NULL);
    BN_sub(s, k, s);
    BN_mod_mul(s, s, dA, EC_GROUP_order(EC_KEY_get0_group(ec_key)), NULL);

    // 将 r 和 s 拼接成签名数据
    unsigned char *p = sig;
    *p++ = 0x30;
    p++; // 后面填充长度
    unsigned char *rpos = p;
    *p++ = 0x02;
    if (BN_num_bits(r) % 8 == 0) {
        *p++ = BN_num_bits(r) / 8;
    } else {
        *p++ = BN_num_bits(r) / 8 + 1;
    }
    BN_bn2bin(r, p);
    p += *rpos + 1;
    unsigned char *spos = p;
    *p++ = 0x02;
    if (BN_num_bits(s) % 8 == 0) {
        *p++ = BN_num_bits(s) / 8;
    } else {
        *p++ = BN_num_bits(s) / 8 + 1;
    }
    BN_bn2bin(s, p);
    p += *spos + 1;

    // 填充签名数据长度
    *spos += 2;
    *rpos += 2;
    *siglen = p - sig;

finish:
    if (ec_key) {
        EC_KEY_free(ec_key);
    }
    if (md_ctx) {
        EVP_MD_CTX_free(md_ctx);
    }
    if (k) {
        BN_free(k);
    }
    if (P) {
        EC_POINT_free(P);
    }
    if (r) {
        BN_free(r);
    }
    if (s) {
        BN_free(s);
    }

    return ret;
}

SM2VerifySig 函数：

#include <openssl/bn.h>
#include <openssl/ec.h>
#include <openssl/evp.h>
#include <openssl/sm2.h>

int SM2VerifySig(const unsigned char *msg, size_t msglen, const char *pubkeyfile, const unsigned char *sig, size_t siglen)
{
    int ret = 0;
    EC_KEY *ec_key = NULL;
    EVP_MD_CTX *md_ctx = NULL;
    unsigned char dgst[32];
    size_t dgstlen;
    const EVP_MD *md;
    BIGNUM *r = NULL, *s = NULL;
    EC_POINT *P = NULL;

    // 读取公钥
    ec_key = EC_KEY_new_by_curve_name(NID_sm2);
    if (!ec_key) {
        goto finish;
    }

    FILE *fp = fopen(pubkeyfile, "r");
    if (!fp) {
        goto finish;
    }

    PEM_read_EC_PUBKEY(fp, &ec_key, NULL, NULL);
    fclose(fp);
    fp = NULL;

    // 解析签名数据
    unsigned char *p = (unsigned char *)sig;
    if (*p++ != 0x30) {
        goto finish;
    }

    size_t len = *p++;
    if (len > siglen - 2) {
        goto finish;
    }

    if (*p++ != 0x02) {
        goto finish;
    }

    size_t rlen = *p++;
    if (rlen > len - 3) {
        goto finish;
    }

    r = BN_new();
    BN_bin2bn(p, rlen, r);
    p += rlen;
    len -= rlen + 2;

    if (*p++ != 0x02) {
        goto finish;
    }

    size_t slen = *p++;
    if (slen != len) {
        goto finish;
    }

    s = BN_new();
    BN_bin2bn(p, slen, s);

    // 计算消息摘要
    md = EVP_sm3();
    md_ctx = EVP_MD_CTX_new();
    EVP_DigestInit_ex(md_ctx, md, NULL);
    EVP_DigestUpdate(md_ctx, msg, msglen);
    EVP_DigestFinal_ex(md_ctx, dgst, &dgstlen);
    EVP_MD_CTX_free(md_ctx);
    md_ctx = NULL;

    // 计算椭圆曲线点 P = [s]G + [r]PA
    P = EC_POINT_new(EC_KEY_get0_group(ec_key));
    EC_POINT *PA = EC_POINT_dup(EC_KEY_get0_public_key(ec_key), EC_KEY_get0_group(ec_key));
    ret = EC_POINT_mul(EC_KEY_get0_group(ec_key), P, s, PA, r, NULL);
    if (ret != 1) {
        goto finish;
    }

    // 计算 e = H(M)
    BIGNUM *e = BN_new();
    BN_bin2bn(dgst, sizeof(dgst), e);

    // 计算 t = (r + x1) mod n
    BIGNUM *t = BN_new();
    const EC_POINT *pubkey = EC_KEY_get0_public_key(ec_key);
    EC_POINT_get_affine_coordinates(EC_KEY_get0_group(ec_key), pubkey, t, NULL, NULL);
    BN_add(t, t, r);
    BN_mod(t, t, EC_GROUP_order(EC_KEY_get0_group(ec_key)), NULL);

    // 验证签名是否正确
    ret = BN_cmp(t, e) == 0;

finish:
    if (ec_key) {
        EC_KEY_free(ec_key);
    }
    if (md_ctx) {
        EVP_MD_CTX_free(md_ctx);
    }
    if (r) {
        BN_free(r);
    }
    if (s) {
        BN_free(s);
    }
    if (P) {
        EC_POINT_free(P);
    }

    return ret;
}

这些函数使用 OpenSSL 库实现了生成非对称密钥对、SM2 签名和验证签名的功能。在编写程序时，需要将 OpenSSL 库链接到程序中。