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[gnulib.git] / lib / hmac-sha1.c

diff --git a/lib/hmac-sha1.c b/lib/hmac-sha1.c
index 9c95791..f7a3fda 100644 (file)
--- a/lib/hmac-sha1.c
+++ b/lib/hmac-sha1.c
@@ -41,6 +41,8 @@ hmac_sha1 (const void *key, size_t keylen,
   char block[64];
   char innerhash[20];
 
+  /* Reduce the key's size, so that it becomes <= 64 bytes large.  */
+
   if (keylen > 64)
     {
       struct sha1_ctx keyhash;
@@ -53,6 +55,8 @@ hmac_sha1 (const void *key, size_t keylen,
       keylen = 20;
     }
 
+  /* Compute INNERHASH from KEY and IN.  */
+
   sha1_init_ctx (&inner);
 
   memset (block, IPAD, sizeof (block));
@@ -63,6 +67,8 @@ hmac_sha1 (const void *key, size_t keylen,
 
   sha1_finish_ctx (&inner, innerhash);
 
+  /* Compute result from KEY and INNERHASH.  */
+
   sha1_init_ctx (&outer);
 
   memset (block, OPAD, sizeof (block));