diff --git a/src/rand_unix.c b/src/rand_unix.c
new file mode 100644
index 00000000..a660dcdd
--- /dev/null
+++ b/src/rand_unix.c
@@ -0,0 +1,40 @@
+/*
+ *  Copyright 2014-2022 The GmSSL Project. All Rights Reserved.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the License); you may
+ *  not use this file except in compliance with the License.
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ */
+
+
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h> // in Linux
+//#include <sys/random.h> // in Apple
+#include <gmssl/rand.h>
+#include <gmssl/error.h>
+
+
+#define RAND_MAX_BUF_SIZE 256 // requirement of getentropy()
+
+int rand_bytes(uint8_t *buf, size_t len)
+{
+	if (!buf) {
+		error_print();
+		return -1;
+	}
+	if (!len || len > RAND_MAX_BUF_SIZE) {
+		error_print();
+		return -1;
+	}
+	if (getentropy(buf, len) != 0) {
+		error_print();
+		return -1;
+	}
+	return 1;
+}
+