openssl编程之x509证书信息解析

// 从文件加载证书
X509* load_certificate_from_file(const char* filename) {
	BIO* bio = BIO_new_file(filename, "r");
	if (!bio) {
		fprintf(stderr, "Error opening certificate file: %s\n", filename);
		return NULL;
	}

	X509* cert = PEM_read_bio_X509(bio, NULL, NULL, NULL);
	BIO_free(bio);

	if (!cert) {
		fprintf(stderr, "Error reading certificate from: %s\n", filename);
	}

	return cert;
}


void print_certificate_details(X509* cert) {
	if (!cert) {
		fprintf(stderr, "Invalid certificate pointer\n");
		return;
	}

	printf("\n=== 证书详细信息 ===\n");

	// 1. 版本信息
	printf("1. 版本: X509v%d\n", X509_get_version(cert) + 1);

	// 2. 序列号
	ASN1_INTEGER* serial = X509_get_serialNumber(cert);
	if (serial) {
		BIGNUM* bn = ASN1_INTEGER_to_BN(serial, NULL);
		if (bn) {
			char* serial_str = BN_bn2dec(bn);
			printf("2. 序列号: %s\n", serial_str);
			OPENSSL_free(serial_str);
			BN_free(bn);
		}
	}

	// 3. 签名算法
	printf("3. 签名算法: ");
	const ASN1_OBJECT* sig_alg_obj = X509_get0_tbs_sigalg(cert)->algorithm;
	char sig_alg_buf[128];
	OBJ_obj2txt(sig_alg_buf, sizeof(sig_alg_buf), sig_alg_obj, 1);
	printf("%s\n", sig_alg_buf);

	// 4. 颁发者信息
	printf("4. 颁发者:\n");
	X509_NAME* issuer = X509_get_issuer_name(cert);
	if (issuer) {
		for (int i = 0; i < X509_NAME_entry_count(issuer); i++) {
			X509_NAME_ENTRY* entry = X509_NAME_get_entry(issuer, i);
			ASN1_OBJECT* obj = X509_NAME_ENTRY_get_object(entry);
			ASN1_STRING* data = X509_NAME_ENTRY_get_data(entry);

			char obj_buf[128];
			OBJ_obj2txt(obj_buf, sizeof(obj_buf), obj, 0);

			unsigned char* data_str = NULL;
			int len = ASN1_STRING_to_UTF8(&data_str, data);
			if (len > 0) {
				printf("   %s: %s\n", obj_buf, data_str);
				OPENSSL_free(data_str);
			}
		}
	}

	// 5. 有效期
	printf("5. 有效期:\n");
	ASN1_TIME* not_before = (ASN1_TIME*)X509_get0_notBefore(cert);
	ASN1_TIME* not_after =(ASN1_TIME*) X509_get0_notAfter(cert);

	if (not_before) {
		BIO* bio = BIO_new(BIO_s_mem());
		ASN1_TIME_print(bio, not_before);
		char time_buf[256];
		int len = BIO_read(bio, time_buf, sizeof(time_buf) - 1);
		time_buf[len] = '\0';
		printf("   生效时间: %s\n", time_buf);
		BIO_free(bio);
	}

	if (not_after) {
		BIO* bio = BIO_new(BIO_s_mem());
		ASN1_TIME_print(bio, not_after);
		char time_buf[256];
		int len = BIO_read(bio, time_buf, sizeof(time_buf) - 1);
		time_buf[len] = '\0';
		printf("   过期时间: %s\n", time_buf);
		BIO_free(bio);
	}

	// 6. 主体信息
	printf("6. 主体:\n");
	X509_NAME* subject = X509_get_subject_name(cert);
	if (subject) {
		for (int i = 0; i < X509_NAME_entry_count(subject); i++) {
			X509_NAME_ENTRY* entry = X509_NAME_get_entry(subject, i);
			ASN1_OBJECT* obj = X509_NAME_ENTRY_get_object(entry);
			ASN1_STRING* data = X509_NAME_ENTRY_get_data(entry);

			char obj_buf[128];
			OBJ_obj2txt(obj_buf, sizeof(obj_buf), obj, 0);

			unsigned char* data_str = NULL;
			int len = ASN1_STRING_to_UTF8(&data_str, data);
			if (len > 0) {
				printf("   %s: %s\n", obj_buf, data_str);
				OPENSSL_free(data_str);
			}
		}
	}

	// 7. 公钥信息
	printf("7. 公钥信息:\n");
	EVP_PKEY* pkey = X509_get_pubkey(cert);
	if (pkey) {
		int type = EVP_PKEY_id(pkey);
		printf("   算法: %s\n", OBJ_nid2ln(type));

		int bits = EVP_PKEY_bits(pkey);
		printf("   密钥长度: %d bits\n", bits);

		EVP_PKEY_free(pkey);
	}

	// 8. 扩展信息
	printf("8. 扩展信息:\n");
	int ext_count = X509_get_ext_count(cert);
	for (int i = 0; i < ext_count; i++) {
		X509_EXTENSION* ext = X509_get_ext(cert, i);
		ASN1_OBJECT* obj = X509_EXTENSION_get_object(ext);

		char ext_buf[128];
		OBJ_obj2txt(ext_buf, sizeof(ext_buf), obj, 0);

		printf("   %s", ext_buf);

		// 显示关键扩展
		if (X509_EXTENSION_get_critical(ext)) {
			printf(" (关键)");
		}
		printf("\n");

		// 显示特定扩展的详细信息
		if (OBJ_obj2nid(obj) == NID_subject_alt_name) {
			printf("     主题备用名称: ");
			BIO* bio = BIO_new(BIO_s_mem());
			//X509V3_EXT_print(bio, ext, 0, 0);
			//nmflag(名称显示标志)
			X509_print_ex(bio, cert, XN_FLAG_COMPAT , X509_FLAG_NO_EXTENSIONS);
			char ext_info[1024];
			int len = BIO_read(bio, ext_info, sizeof(ext_info) - 1);
			if (len > 0) {
				ext_info[len] = '\0';
				printf("%s", ext_info);
			}
			BIO_free(bio);
			printf("\n");
		}
	}

	// 9. 证书指纹
	printf("9. 指纹:\n");
	unsigned char md[EVP_MAX_MD_SIZE];
	unsigned int len;

	if (X509_digest(cert, EVP_sha1(), md, &len)) {
		printf("   SHA-1: ");
		for (unsigned int i = 0; i < len; i++) {
			printf("%02X", md[i]);
			if (i < len - 1) printf(":");
		}
		printf("\n");
	}

	if (X509_digest(cert, EVP_sha256(), md, &len)) {
		printf("   SHA-256: ");
		for (unsigned int i = 0; i < len; i++) {
			printf("%02X", md[i]);
			if (i < len - 1) printf(":");
		}
		printf("\n");
	}

	printf("=== 证书信息结束 ===\n\n");
}


int openssl_rsa() {
	

	X509 *x509=load_certificate_from_file("ca.crt");
	print_certificate_details(x509);

	return 0;
}