diff --git a/include/sha1.h b/include/sha1.h
index 734d1fb..da09dab 100644
--- a/include/sha1.h
+++ b/include/sha1.h
@@ -59,7 +59,8 @@ void sha1_starts( sha1_context *ctx );
  * \param input    buffer holding the  data
  * \param ilen	   length of the input data
  */
-void sha1_update( sha1_context *ctx, unsigned char *input, int ilen );
+void sha1_update(sha1_context *ctx, const unsigned char *input,
+		 unsigned int ilen);
 
 /**
  * \brief	   SHA-1 final digest
@@ -76,8 +77,8 @@ void sha1_finish( sha1_context *ctx, unsigned char output[20] );
  * \param ilen	   length of the input data
  * \param output   SHA-1 checksum result
  */
-void sha1_csum( unsigned char *input, int ilen,
-		unsigned char output[20] );
+void sha1_csum(const unsigned char *input, unsigned int ilen,
+		unsigned char *output);
 
 /**
  * \brief	   Output = SHA-1( input buffer ), with watchdog triggering
@@ -87,17 +88,8 @@ void sha1_csum( unsigned char *input, int ilen,
  * \param output   SHA-1 checksum result
  * \param chunk_sz watchdog triggering period (in bytes of input processed)
  */
-void sha1_csum_wd (unsigned char *input, int ilen,
-		unsigned char output[20], unsigned int chunk_sz);
-
-/**
- * \brief	   Output = SHA-1( file contents )
- *
- * \param path	   input file name
- * \param output   SHA-1 checksum result
- * \return	   0 if successful, or 1 if fopen failed
- */
-int sha1_file( char *path, unsigned char output[20] );
+void sha1_csum_wd(const unsigned char *input, unsigned int ilen,
+		unsigned char *output, unsigned int chunk_sz);
 
 /**
  * \brief	   Output = HMAC-SHA-1( input buffer, hmac key )
@@ -108,9 +100,9 @@ int sha1_file( char *path, unsigned char output[20] );
  * \param ilen	   length of the input data
  * \param output   HMAC-SHA-1 result
  */
-void sha1_hmac( unsigned char *key, int keylen,
-		unsigned char *input, int ilen,
-		unsigned char output[20] );
+void sha1_hmac(const unsigned char *key, int keylen,
+		const unsigned char *input, unsigned int ilen,
+		unsigned char *output);
 
 /**
  * \brief	   Checkup routine
diff --git a/lib/sha1.c b/lib/sha1.c
index da5bc16..a121224 100644
--- a/lib/sha1.c
+++ b/lib/sha1.c
@@ -73,7 +73,7 @@ void sha1_starts (sha1_context * ctx)
 	ctx->state[4] = 0xC3D2E1F0;
 }
 
-static void sha1_process (sha1_context * ctx, unsigned char data[64])
+static void sha1_process(sha1_context *ctx, const unsigned char data[64])
 {
 	unsigned long temp, W[16], A, B, C, D, E;
 
@@ -230,7 +230,8 @@ static void sha1_process (sha1_context * ctx, unsigned char data[64])
 /*
  * SHA-1 process buffer
  */
-void sha1_update (sha1_context * ctx, unsigned char *input, int ilen)
+void sha1_update(sha1_context *ctx, const unsigned char *input,
+		 unsigned int ilen)
 {
 	int fill;
 	unsigned long left;
@@ -305,7 +306,8 @@ void sha1_finish (sha1_context * ctx, unsigned char output[20])
 /*
  * Output = SHA-1( input buffer )
  */
-void sha1_csum (unsigned char *input, int ilen, unsigned char output[20])
+void sha1_csum(const unsigned char *input, unsigned int ilen,
+	       unsigned char *output)
 {
 	sha1_context ctx;
 
@@ -318,12 +320,12 @@ void sha1_csum (unsigned char *input, int ilen, unsigned char output[20])
  * Output = SHA-1( input buffer ). Trigger the watchdog every 'chunk_sz'
  * bytes of input processed.
  */
-void sha1_csum_wd (unsigned char *input, int ilen, unsigned char output[20],
-			unsigned int chunk_sz)
+void sha1_csum_wd(const unsigned char *input, unsigned int ilen,
+		  unsigned char *output, unsigned int chunk_sz)
 {
 	sha1_context ctx;
 #if defined(CONFIG_HW_WATCHDOG) || defined(CONFIG_WATCHDOG)
-	unsigned char *end, *curr;
+	const unsigned char *end, *curr;
 	int chunk;
 #endif
 
@@ -350,8 +352,9 @@ void sha1_csum_wd (unsigned char *input, int ilen, unsigned char output[20],
 /*
  * Output = HMAC-SHA-1( input buffer, hmac key )
  */
-void sha1_hmac (unsigned char *key, int keylen,
-		unsigned char *input, int ilen, unsigned char output[20])
+void sha1_hmac(const unsigned char *key, int keylen,
+	       const unsigned char *input, unsigned int ilen,
+	       unsigned char *output)
 {
 	int i;
 	sha1_context ctx;