New internal functions _aes_set_key and _aes_invert.

1 files changed, 8 insertions, 29 deletions

diff --git a/aes-set-encrypt-key.c b/aes-set-encrypt-key.c
index d96a8ebc..a3f20a13 100644
--- a/aes-set-encrypt-key.c
+++ b/aes-set-encrypt-key.c
@@ -6,6 +6,7 @@
 /* nettle, low-level cryptographics library
  *
  * Copyright (C) 2000, 2001, 2002 Rafael R. Sevilla, Niels Möller
+ * Copyright (C) 2013 Niels Möller
  *  
  * The nettle library is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -32,50 +33,28 @@
 #include <assert.h>
 
 #include "aes-internal.h"
-#include "macros.h"
 
 void
 aes_set_encrypt_key(struct aes_ctx *ctx,
 		    size_t keysize, const uint8_t *key)
 {
-  static const uint8_t rcon[10] = {
-    0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0x1b,0x36,
-  };
-  unsigned nk, nr, i, lastkey;
-  uint32_t temp;
-  const uint8_t *rp;
+  unsigned nk, nr;
 
   assert(keysize >= AES_MIN_KEY_SIZE);
   assert(keysize <= AES_MAX_KEY_SIZE);
   
   /* Truncate keysizes to the valid key sizes provided by Rijndael */
-  if (keysize == 32) {
+  if (keysize == AES256_KEY_SIZE) {
     nk = 8;
-    nr = 14;
-  } else if (keysize >= 24) {
+    nr = _AES256_ROUNDS;
+  } else if (keysize >= AES192_KEY_SIZE) {
     nk = 6;
-    nr = 12;
+    nr = _AES192_ROUNDS;
   } else { /* must be 16 or more */
     nk = 4;
-    nr = 10;
+    nr = _AES128_ROUNDS;
   }
 
-  lastkey = (AES_BLOCK_SIZE/4) * (nr + 1);
   ctx->rounds = nr;
-
-  for (i=0, rp = rcon; i<nk; i++)
-    ctx->keys[i] = LE_READ_UINT32(key + i*4);
-
-  for (i=nk; i<lastkey; i++)
-    {
-      temp = ctx->keys[i-1];
-      if (i % nk == 0)
-	temp = SUBBYTE(ROTL32(24, temp), aes_sbox) ^ *rp++;
-
-      else if (nk > 6 && (i%nk) == 4)
-	temp = SUBBYTE(temp, aes_sbox);
-
-      ctx->keys[i] = ctx->keys[i-nk] ^ temp;
-    }
+  _aes_set_key (nr, nk, ctx->keys, key);
 }
-