OpenSSL-SM2

sm2_sign.c:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/ec.h>
#include <openssl/evp.h>

int main(void) {
int ret = -1, i;
EVP_PKEY_CTX *pctx = NULL, *ectx = NULL;
EVP_PKEY *pkey = NULL;
unsigned char message[16] = "2020121220201212";//{ 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF };
size_t message_len = sizeof(message);
unsigned char *ciphertext = NULL, *plaintext = NULL;
size_t ciphertext_len, plaintext_len;
EC_KEY *key_pair = NULL;
const BIGNUM *priv_key = NULL;
char *priv_key_str = NULL;

const EC_GROUP *group = NULL;
const EC_POINT *pub_key = NULL;
BN_CTX *ctx = NULL;
BIGNUM *x_coordinate = NULL, *y_coordinate = NULL;
char *x_coordinate_str = NULL, *y_coordinate_str = NULL;

/* create SM2 Ellipse Curve parameters and key pair */
if ( !(pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_EC, NULL)) ) {
goto clean_up;
}

if ( (EVP_PKEY_paramgen_init(pctx)) != 1 ) {
goto clean_up;
}

if ( (EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, NID_sm2)) <= 0 ) {
goto clean_up;
}

if ( (EVP_PKEY_keygen_init(pctx)) != 1 ) {
goto clean_up;
}

if ( (EVP_PKEY_keygen(pctx, &pkey)) != 1 ) {
goto clean_up;
}

/* print SM2 key pair */
if ( !(key_pair = EVP_PKEY_get0_EC_KEY(pkey)) ) {
goto clean_up;
}

if ( !(priv_key = EC_KEY_get0_private_key(key_pair)) ) {
goto clean_up;
}

if ( !(priv_key_str = BN_bn2hex(priv_key)) ) {
goto clean_up;
}
printf("SM2 private key (in hex form):\n");
printf("%s\n\n", priv_key_str);

if ( !(pub_key = EC_KEY_get0_public_key(key_pair)) ) {
goto clean_up;
}

if ( !(group = EC_KEY_get0_group(key_pair)) ) {
goto clean_up;
}

if ( !(ctx = BN_CTX_new()) ) {
goto clean_up;
}
BN_CTX_start(ctx);
x_coordinate = BN_CTX_get(ctx);
y_coordinate = BN_CTX_get(ctx);
if ( !(y_coordinate) ) {
goto clean_up;
}
if ( !(EC_POINT_get_affine_coordinates(group, pub_key, x_coordinate, y_coordinate, ctx)) ) {
goto clean_up;
}
if ( !(x_coordinate_str = BN_bn2hex(x_coordinate)) ) {
goto clean_up;
}
printf("x coordinate in SM2 public key (in hex form):\n");
printf("%s\n\n", x_coordinate_str);

if ( !(y_coordinate_str = BN_bn2hex(y_coordinate)) ) {
goto clean_up;
}
printf("y coordinate in SM2 public key (in hex form):\n");
printf("%s\n\n", y_coordinate_str);

/* compute SM2 encryption */
if ( (EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2)) != 1 ) {
goto clean_up;
}

if ( !(ectx = EVP_PKEY_CTX_new(pkey, NULL)) ) {
goto clean_up;
}

if ( (EVP_PKEY_encrypt_init(ectx)) != 1 ) {
goto clean_up;
}

if ( (EVP_PKEY_encrypt(ectx, NULL, &ciphertext_len, message, message_len)) != 1 ) {
goto clean_up;
}

if ( !(ciphertext = (unsigned char *)malloc(ciphertext_len)) ) {
goto clean_up;
}

if ( (EVP_PKEY_encrypt(ectx, ciphertext, &ciphertext_len, message, message_len)) != 1 ) {
goto clean_up;
}

printf("Message length: %ld bytes.\n", message_len);
printf("Message:\n");
for (i = 0; i < (int)message_len; i++) {
printf("0x%x ", message[i]);
}
printf("\n\n");

printf("Ciphertext length: %ld bytes.\n", ciphertext_len);
printf("Ciphertext (ASN.1 encode):\n");
for (i = 0; i < (int)ciphertext_len; i++) {
printf("0x%x ", ciphertext[i]);
}
printf("\n\n");

/* compute SM2 decryption */
if ( (EVP_PKEY_decrypt_init(ectx)) != 1 ) {
goto clean_up;
}

if ( (EVP_PKEY_decrypt(ectx, NULL, &plaintext_len, ciphertext, ciphertext_len)) != 1 ) {
goto clean_up;
}

if ( !(plaintext = (unsigned char *)malloc(plaintext_len)) ) {
goto clean_up;
}

if ( (EVP_PKEY_decrypt(ectx, plaintext, &plaintext_len, ciphertext, ciphertext_len)) != 1 ) {
goto clean_up;
}

printf("Decrypted plaintext length: %ld bytes.\n", plaintext_len);
printf("Decrypted plaintext:\n");
for (i = 0; i < (int)plaintext_len; i++) {
printf("0x%x ", plaintext[i]);
}
printf("\n\n");

if ( plaintext_len != message_len ) {
printf("Decrypted data length error!\n");
goto clean_up;
}

if ( memcmp(plaintext, message, message_len) ) {
printf("Decrypt data failed!\n");
goto clean_up;
} else {
printf("Encrypt and decrypt data succeeded!\n");
}

ret = 0;
clean_up:
if (pctx) {
EVP_PKEY_CTX_free(pctx);
}

if (pkey) {
EVP_PKEY_free(pkey);
}

if (priv_key_str) {
OPENSSL_free(priv_key_str);
}

if (ctx) {
BN_CTX_end(ctx);
BN_CTX_free(ctx);
}

if (x_coordinate_str) {
OPENSSL_free(x_coordinate_str);
}

if (y_coordinate_str) {
OPENSSL_free(y_coordinate_str);
}

if (ectx) {
EVP_PKEY_CTX_free(ectx);
}

if (ciphertext) {
free(ciphertext);
}

if (plaintext) {
free(plaintext);
}

return 0;
}

sm2_enc_dec.c: