diff --git a/src/sm3_kdf.c b/src/sm3_kdf.c
index a2f46bff..fd9a459e 100644
--- a/src/sm3_kdf.c
+++ b/src/sm3_kdf.c
@@ -1,5 +1,5 @@
 /*
- *  Copyright 2014-2022 The GmSSL Project. All Rights Reserved.
+ *  Copyright 2014-2023 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.
@@ -8,13 +8,17 @@
  */
 
 
-
 #include <string.h>
 #include <gmssl/sm3.h>
-#include <gmssl/endian.h>
 #include <gmssl/error.h>
 
 
+#define PUTU32(ptr,a) \
+	((ptr)[0] = (uint8_t)((a) >> 24), \
+	 (ptr)[1] = (uint8_t)((a) >> 16), \
+	 (ptr)[2] = (uint8_t)((a) >>  8), \
+	 (ptr)[3] = (uint8_t)(a))
+
 void sm3_kdf_init(SM3_KDF_CTX *ctx, size_t outlen)
 {
 	sm3_init(&ctx->sm3_ctx);
@@ -52,3 +56,15 @@ void sm3_kdf_finish(SM3_KDF_CTX *ctx, uint8_t *out)
 	memset(&sm3_ctx, 0, sizeof(SM3_CTX));
 	memset(dgst, 0, sizeof(dgst));
 }
+
+#if 0
+// add until v3.2.0
+void sm3_kdf(const uint8_t *in, size_t inlen, size_t outlen, uint8_t *out)
+{
+	SM3_KDF_CTX ctx;
+	sm3_kdf_init(&ctx, outlen);
+	sm3_kdf_update(&ctx, in, inlen);
+	sm3_kdf_finish(&ctx, out);
+	memset(&ctx, 0, sizeof(ctx));
+}
+#endif