Add SM9 demos

demos/sm9/sm9_sign_demo.c

@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <gmssl/sm9.h>
+#include <gmssl/error.h>
+
+
+int main(void)
+{
+	SM9_SIGN_MASTER_KEY sign_master;
+	SM9_SIGN_MASTER_KEY sign_master_public;
+	SM9_SIGN_KEY sign_key;
+	SM9_SIGN_CTX sign_ctx;
+	const char *id = "Alice";
+	uint8_t sig[SM9_SIGNATURE_SIZE];
+	size_t siglen;
+	uint8_t buf[512];
+	uint8_t *p = buf;
+	const uint8_t *cp = buf;
+	size_t len;
+	int ret;
+
+	sm9_sign_master_key_generate(&sign_master);
+
+	sm9_sign_master_key_extract_key(&sign_master, id, strlen(id), &sign_key);
+
+	sm9_sign_init(&sign_ctx);
+	sm9_sign_update(&sign_ctx, (uint8_t *)"hello world", strlen("hello world"));
+	sm9_sign_finish(&sign_ctx, &sign_key, sig, &siglen);
+
+	format_bytes(stdout, 0, 0, "signature", sig, siglen);
+
+
+	sm9_sign_master_public_key_to_der(&sign_master, &p, &len);
+	sm9_sign_master_public_key_from_der(&sign_master_public, &cp, &len);
+
+	sm9_verify_init(&sign_ctx);
+	sm9_verify_update(&sign_ctx, (uint8_t *)"hello world", strlen("hello world"));
+	ret = sm9_verify_finish(&sign_ctx, sig, siglen, &sign_master_public, id, strlen(id));
+	printf("verify %s\n", ret == 1 ? "success" : "failure");
+
+
+	return 0;
+}