--- a/svr-authpubkey.c	Tue Jan 23 23:27:40 2018 +0800
+++ b/svr-authpubkey.c	Sat Feb 17 19:29:51 2018 +0800
@@ -70,11 +70,11 @@
 #define MIN_AUTHKEYS_LINE 10 /* "ssh-rsa AB" - short but doesn't matter */
 #define MAX_AUTHKEYS_LINE 4200 /* max length of a line in authkeys */
 
-static int checkpubkey(char* algo, unsigned int algolen,
-		unsigned char* keyblob, unsigned int keybloblen);
+static int checkpubkey(const char* algo, unsigned int algolen,
+		const unsigned char* keyblob, unsigned int keybloblen);
 static int checkpubkeyperms(void);
-static void send_msg_userauth_pk_ok(char* algo, unsigned int algolen,
-		unsigned char* keyblob, unsigned int keybloblen);
+static void send_msg_userauth_pk_ok(const char* algo, unsigned int algolen,
+		const unsigned char* keyblob, unsigned int keybloblen);
 static int checkfileperm(char * filename);
 
 /* process a pubkey auth request, sending success or failure message as
@@ -173,8 +173,8 @@
 /* Reply that the key is valid for auth, this is sent when the user sends
  * a straight copy of their pubkey to test, to avoid having to perform
  * expensive signing operations with a worthless key */
-static void send_msg_userauth_pk_ok(char* algo, unsigned int algolen,
-		unsigned char* keyblob, unsigned int keybloblen) {
+static void send_msg_userauth_pk_ok(const char* algo, unsigned int algolen,
+		const unsigned char* keyblob, unsigned int keybloblen) {
 
 	TRACE(("enter send_msg_userauth_pk_ok"))
 	CHECKCLEARTOWRITE();
@@ -188,7 +188,7 @@
 
 }
 
-static int checkpubkey_line(buffer* line, int line_num, char* filename,
+static int checkpubkey_line(buffer* line, int line_num, const char* filename,
 		const char* algo, unsigned int algolen,
 		const unsigned char* keyblob, unsigned int keybloblen) {
 	buffer *options_buf = NULL;
@@ -292,8 +292,8 @@
 /* Checks whether a specified publickey (and associated algorithm) is an
  * acceptable key for authentication */
 /* Returns DROPBEAR_SUCCESS if key is ok for auth, DROPBEAR_FAILURE otherwise */
-static int checkpubkey(char* algo, unsigned int algolen,
-		unsigned char* keyblob, unsigned int keybloblen) {
+static int checkpubkey(const char* algo, unsigned int algolen,
+		const unsigned char* keyblob, unsigned int keybloblen) {
 
 	FILE * authfile = NULL;
 	char * filename = NULL;