Compute SM2 signature and verify it by invoking EVP interface in OpenSSL 1.1.1

        SM2 algorithm is supported in OpenSSL 1.1.1. A rough introduction on SM2 operation is given in: https://www.openssl.org/docs/manmaster/man7/SM2.html . But it is not sufficient for learners to grasp it. A demo program is provided here:

/**************************************************
* File name: EVP_sm2_sign_and_verify.c
* Author: HAN Wei
* Author's blog: https://blog.csdn.net/henter/
* Date: April 27th, 2020
* Description: demonstrate how to compute SM2 signature
               and verify it by invoking EVP interface
			   in OpenSSL 1.1.1
**************************************************/
 
#include <stdio.h>
#include <stdlib.h>
#include "openssl/ec.h"
#include "openssl/evp.h"
 
/**************************************************
* Main function return value:
    0:   main function executes successfully
    -1:  an error occurs
**************************************************/
int main(void)
{
	int ret = -1, i;
	EVP_PKEY_CTX *pctx = NULL, *sctx = NULL;
	EVP_PKEY *pkey = NULL;
	EVP_MD_CTX *md_ctx = NULL, * md_ctx_verify = NULL;
	unsigned char message[16] = {0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,
	                             0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF};
        size_t message_len = sizeof(message);
        unsigned char *sig = NULL;
        size_t sig_len;
        unsigned char sm2_id[] = {0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
                                  0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38};
        unsigned int sm2_id_len = sizeof(sm2_id);
	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_******_init(pctx)) != 1 )
	{
		goto clean_up; 
	}
	
	if ( (EVP_PKEY_******(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("SM2 public key x coordinate (in hex form):\n");
	printf("%s\n\n", x_coordinate_str);
 
	if ( !(y_coordinate_str = BN_bn2hex(y_coordinate)) )
	{
		goto clean_up;
	}
	printf("SM2 public key y coordinate (in hex form):\n");
	printf("%s\n\n", y_coordinate_str);
 
/* compute SM2 signature */
	if ( (EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2)) != 1 )
	{
		goto clean_up;
	}
 
	if ( !(md_ctx = EVP_MD_CTX_new()) )
	{
		goto clean_up;
	}
 
	if ( !(sctx = EVP_PKEY_CTX_new(pkey, NULL)) )
	{
		goto clean_up;
	}
 
	if ( EVP_PKEY_CTX_set1_id(sctx, sm2_id, sm2_id_len) <= 0 )
	{
		goto clean_up;
	}
 
	EVP_MD_CTX_set_pkey_ctx(md_ctx, sctx);
 
	if ( (EVP_DigestSignInit(md_ctx, NULL, EVP_sm3(), NULL, pkey)) != 1 )
	{
		goto clean_up;
	}
 
	if ( (EVP_DigestSignUpdate(md_ctx, message, message_len)) != 1 )
	{
		goto clean_up;
	}
 
	if ( (EVP_DigestSignFinal(md_ctx, NULL, &sig_len)) != 1 )
	{
		goto clean_up;
	}
 
	if ( !(sig = (unsigned char *)malloc(sig_len)) )
        {
        goto clean_up;
        }
 
	if ( (EVP_DigestSignFinal(md_ctx, sig, &sig_len)) != 1 )
	{
		goto clean_up;
	}
 
	printf("Message length: %d bytes.\n", message_len);
	printf("Message:\n");
	for (i = 0; i < (int)message_len; i++)
	{
		printf("0x%x  ", message[i]);
	}
	printf("\n\n");
 
	printf("SM2 signature length: %d bytes.\n", sig_len);
	printf("SM2 signature (ASN.1 encode):\n");
	for (i = 0; i < (int)sig_len; i++)
	{
		printf("0x%x  ", sig[i]);
	}
	printf("\n\n");
 
/* verify SM2 signature */
	if ( !(md_ctx_verify = EVP_MD_CTX_new()) )
	{
		goto clean_up;
	}
 
	EVP_MD_CTX_set_pkey_ctx(md_ctx_verify, sctx);
 
	if ( (EVP_DigestVerifyInit(md_ctx_verify, NULL, EVP_sm3(), NULL, pkey)) != 1 )
	{
		goto clean_up;
	}
 
	if ( (EVP_DigestVerifyUpdate(md_ctx_verify, message, sizeof(message))) != 1 )
	{
		goto clean_up;
	}
 
	if ( (EVP_DigestVerifyFinal(md_ctx_verify, sig, sig_len)) != 1 )
	{
		printf("Verify SM2 signature failed!\n");
		goto clean_up;
	}
	else
	{
		printf("Verify SM2 signature succeed!\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 (md_ctx)
	{
		EVP_MD_CTX_free(md_ctx);
	}
 
	if (sctx)
	{
		EVP_PKEY_CTX_free(sctx);
	}
 
	if (sig)
	{
		free(sig);
	}
 
	if (md_ctx_verify)
	{
		EVP_MD_CTX_free(md_ctx_verify);
	}
 
#if defined(_WIN32) || defined(_WIN64)
	system("pause");
#endif
	return ret;
}

        The result is as below: