Update some demos

demos/sm2/sm2-encrypt.c

@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <libgen.h>
+#include <openssl/ec.h>
+#include <openssl/sm2.h>
+#include <openssl/evp.h>
+#include <openssl/err.h>
+#include <openssl/rand.h>
+#include <openssl/objects.h>
+#include <openssl/is_gmssl.h>
+
+
+int main(int argc, char **argv)
+{
+	int ret = -1;
+	EC_KEY *ec_key = NULL;
+	unsigned char key[64];
+	unsigned char cbuf[1024];
+	unsigned char pbuf[1024] = {0};
+	size_t clen = sizeof(cbuf);
+	size_t plen = sizeof(pbuf);
+	int i;
+
+	/* generate sm2 key pair */
+	if (!(ec_key = EC_KEY_new_by_curve_name(NID_sm2p256v1))
+		|| !EC_KEY_generate_key(ec_key)) {
+		ERR_print_errors_fp(stderr);
+		goto end;
+	}
+
+	/* generate to be encrypted symmetric key
+	 * Notice: sm2 encrypt should only be used to encrypt short data
+	 */
+	if (!RAND_bytes(key, sizeof(key))) {
+		ERR_print_errors_fp(stderr);
+		goto end;
+	}
+
+	printf("M = ");
+	for (i = 0; i < sizeof(key); i++) {
+		printf("%02X", key[i]);
+	}
+	printf("\n");
+
+	/* sm2 encrypt, hash algorithm is required for KDF */
+	if (!SM2_encrypt(NID_sm3, key, sizeof(key), cbuf, &clen, ec_key)) {
+		ERR_print_errors_fp(stderr);
+		goto end;
+	}
+
+	printf("C = ");
+	for (i = 0; i < clen; i++) {
+		printf("%02X", cbuf[i]);
+	}
+	printf("\n");
+
+	/* sm2 decrypt */
+	if (!SM2_decrypt(NID_sm3, cbuf, clen, pbuf, &plen, ec_key)) {
+		ERR_print_errors_fp(stderr);
+		goto end;
+	}
+
+	printf("M' = ");
+	for (i = 0; i < plen; i++) {
+		printf("%02X", pbuf[i]);
+	}
+	printf("\n");
+
+	ret = 0;
+
+end:
+	EC_KEY_free(ec_key);
+	return ret;
+}