SM2、SM3和SM4详细算法C语言编写

以下是SM2、SM3和SM4算法的C语言实现：

SM2算法：

#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/evp.h>
#include <openssl/bn.h>
#include <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/objects.h>

int sm2_keypair(unsigned char *pubkey, unsigned char *prikey) {
    EC_KEY *key = EC_KEY_new_by_curve_name(NID_sm2);
    if (key == NULL) {
        return 0;
    }

    if (!EC_KEY_generate_key(key)) {
        return 0;
    }

    const EC_GROUP *group = EC_KEY_get0_group(key);
    const EC_POINT *point = EC_KEY_get0_public_key(key);
    const BIGNUM *pkey = EC_KEY_get0_private_key(key);

    BIGNUM *x = BN_new();
    BIGNUM *y = BN_new();
    BN_CTX *ctx = BN_CTX_new();

    if (!EC_POINT_get_affine_coordinates_GFp(group, point, x, y, NULL)) {
        return 0;
    }

    int len = 32;
    if (len > BN_num_bytes(pkey)) {
        len = BN_num_bytes(pkey);
    }
    memset(prikey, 0, 32 - len);
    BN_bn2bin(pkey, prikey + 32 - len);
    BN_bn2bin(x, pubkey);
    BN_bn2bin(y, pubkey + 32);

    BN_free(x);
    BN_free(y);
    BN_CTX_free(ctx);
    EC_KEY_free(key);

    return 1;
}

SM3算法：

#include <openssl/evp.h>
#include <openssl/sm3.h>
#include <string.h>

int sm3(unsigned char *in, size_t ilen, unsigned char *out) {
    EVP_MD_CTX *mdctx;
    const EVP_MD *md;
    unsigned int md_len;
    md = EVP_sm3();
    mdctx = EVP_MD_CTX_create();
    EVP_DigestInit_ex(mdctx, md, NULL);
    EVP_DigestUpdate(mdctx, in, ilen);
    EVP_DigestFinal_ex(mdctx, out, &md_len);
    EVP_MD_CTX_destroy(mdctx);

    return 1;
}

SM4算法：

#include <openssl/evp.h>
#include <openssl/sm4.h>
#include <string.h>

int sm4_ecb_encrypt(unsigned char *in, int inlen, unsigned char *out, unsigned char *key, int keylen, int enc) {
    EVP_CIPHER_CTX *ctx;
    const EVP_CIPHER *cipher;

    cipher = EVP_sm4_ecb();
    ctx = EVP_CIPHER_CTX_new();
    EVP_CipherInit_ex(ctx, cipher, NULL, key, NULL, enc);
    EVP_CIPHER_CTX_set_padding(ctx, 0);
    int outlen;
    EVP_CipherUpdate(ctx, out, &outlen, in, inlen);
    int tmplen;
    EVP_CipherFinal_ex(ctx, out + outlen, &tmplen);
    outlen += tmplen;
    EVP_CIPHER_CTX_free(ctx);

    return outlen;
}

以上代码基于OpenSSL库实现，可以在Linux或Windows平台上编译运行。