--- a/signkey.h	Tue Jan 23 22:44:18 2018 +0800
+++ b/signkey.h	Thu Jan 25 21:55:25 2018 +0800
@@ -90,14 +90,14 @@
 void buf_put_pub_key(buffer* buf, sign_key *key, enum signkey_type type);
 void buf_put_priv_key(buffer* buf, sign_key *key, enum signkey_type type);
 void sign_key_free(sign_key *key);
-void buf_put_sign(buffer* buf, sign_key *key, enum signkey_type type, buffer *data_buf);
+void buf_put_sign(buffer* buf, sign_key *key, enum signkey_type type, const buffer *data_buf);
 #if DROPBEAR_SIGNKEY_VERIFY
-int buf_verify(buffer * buf, sign_key *key, buffer *data_buf);
-char * sign_key_fingerprint(unsigned char* keyblob, unsigned int keybloblen);
+int buf_verify(buffer * buf, sign_key *key, const buffer *data_buf);
+char * sign_key_fingerprint(const unsigned char* keyblob, unsigned int keybloblen);
 #endif
 int cmp_base64_key(const unsigned char* keyblob, unsigned int keybloblen, 
 					const unsigned char* algoname, unsigned int algolen, 
-					buffer * line, char ** fingerprint);
+					const buffer * line, char ** fingerprint);
 
 void** signkey_key_ptr(sign_key *key, enum signkey_type type);