Optimizze ocb_update.

1 files changed, 71 insertions, 44 deletions

diff --git a/ocb.c b/ocb.c
index 0c2a7f12..bf3bf72f 100644
--- a/ocb.c
+++ b/ocb.c
@@ -130,51 +130,21 @@ ocb_set_nonce (struct ocb_ctx *ctx,
   ctx->data_count = ctx->message_count = 0;
 }
 
-void
-ocb_update (struct ocb_ctx *ctx, const struct ocb_key *key,
-	    const void *cipher, nettle_cipher_func *f,
-	    size_t length, const uint8_t *data)
-{
-  assert (ctx->message_count == 0);
-
-  if (ctx->data_count == 0)
-    ctx->offset.u64[0] = ctx->offset.u64[1] = 0;
-
-  for (; length >= OCB_BLOCK_SIZE;
-       length -= OCB_BLOCK_SIZE, data += OCB_BLOCK_SIZE)
-    {
-      union nettle_block16 block;
-      update_offset (key, &ctx->offset, ++ctx->data_count);
-      memxor3 (block.b, ctx->offset.b, data, OCB_BLOCK_SIZE);
-      f (cipher, OCB_BLOCK_SIZE, block.b, block.b);
-      block16_xor (&ctx->sum, &block);
-    }
-  if (length > 0)
-    {
-      union nettle_block16 block;
-      pad_block (&block, length, data);
-      block16_xor (&ctx->offset, &key->L[0]);
-      block16_xor (&block, &ctx->offset);
-
-      f (cipher, OCB_BLOCK_SIZE, block.b, block.b);
-      block16_xor (&ctx->sum, &block);
-    }
-}
-
 static void
-ocb_fill_n (struct ocb_ctx *ctx, const struct ocb_key *key,
+ocb_fill_n (const struct ocb_key *key,
+	    union nettle_block16 *offset, size_t count,
 	    size_t n, union nettle_block16 *o)
 {
   assert (n > 0);
   union nettle_block16 *prev;
-  if (ctx->message_count & 1)
-    prev = &ctx->offset;
+  if (count & 1)
+    prev = offset;
   else
     {
       /* Do a single block to align block count. */
-      ++ctx->message_count; /* Always odd. */
-      block16_xor (&ctx->offset, &key->L[2]);
-      block16_set (&o[0], &ctx->offset);
+      count++; /* Always odd. */
+      block16_xor (offset, &key->L[2]);
+      block16_set (&o[0], offset);
       prev = o;
       n--; o++;
     }
@@ -182,24 +152,78 @@ ocb_fill_n (struct ocb_ctx *ctx, const struct ocb_key *key,
   for (; n >= 2; n -= 2, o += 2)
     {
       size_t i;
-      ctx->message_count += 2; /* Always odd. */
+      count += 2; /* Always odd. */
 
       /* Based on trailing zeros of ctx->message_count - 1, the
          initial shift below discards a one bit. */
       block16_mulx_be (&o[0], &key->L[2]);
-      for (i = ctx->message_count >> 1; !(i&1); i >>= 1)
+      for (i = count >> 1; !(i&1); i >>= 1)
 	block16_mulx_be (&o[0], &o[0]);
 
       block16_xor (&o[0], prev);
       block16_xor3 (&o[1], &o[0], &key->L[2]);
       prev = &o[1];
     }
-  block16_set(&ctx->offset, prev);
+  block16_set(offset, prev);
 
   if (n > 0)
     {
-      update_offset (key, &ctx->offset, ++ctx->message_count);
-      block16_set (o, &ctx->offset);
+      update_offset (key, offset, ++count);
+      block16_set (o, offset);
+    }
+}
+
+void
+ocb_update (struct ocb_ctx *ctx, const struct ocb_key *key,
+	    const void *cipher, nettle_cipher_func *f,
+	    size_t length, const uint8_t *data)
+{
+  union nettle_block16 block[OCB_MAX_BLOCKS];
+  size_t n = length / OCB_BLOCK_SIZE;
+  assert (ctx->message_count == 0);
+
+  if (ctx->data_count == 0)
+    ctx->offset.u64[0] = ctx->offset.u64[1] = 0;
+
+  while (n > OCB_MAX_BLOCKS)
+    {
+      size_t blocks = OCB_MAX_BLOCKS - 1 + (ctx->data_count & 1);
+      size_t size, i;
+      ocb_fill_n (key, &ctx->offset, ctx->data_count, blocks, block);
+      ctx->data_count += blocks;
+
+      size = blocks * OCB_BLOCK_SIZE;
+      memxor (block[0].b, data, size);
+      f (cipher, size, block[0].b, block[0].b);
+      for (i = 0; i < blocks; i++)
+	block16_xor(&ctx->sum, &block[i]);
+
+      n -= blocks; data += size;
+    }
+  if (n > 0)
+    {
+      size_t size, i;
+      ocb_fill_n (key, &ctx->offset, ctx->data_count, n, block);
+      ctx->data_count += n;
+
+      size = n * OCB_BLOCK_SIZE;
+      memxor (block[0].b, data, size);
+      f (cipher, size, block[0].b, block[0].b);
+      for (i = 0; i < n; i++)
+	block16_xor(&ctx->sum, &block[i]);
+
+      data += size;
+    }
+  length &= 15;
+  if (length > 0)
+    {
+      union nettle_block16 block;
+      pad_block (&block, length, data);
+      block16_xor (&ctx->offset, &key->L[0]);
+      block16_xor (&block, &ctx->offset);
+
+      f (cipher, OCB_BLOCK_SIZE, block.b, block.b);
+      block16_xor (&ctx->sum, &block);
     }
 }
 
@@ -214,7 +238,8 @@ ocb_crypt_n (struct ocb_ctx *ctx, const struct ocb_key *key,
   while (n > OCB_MAX_BLOCKS)
     {
       size_t blocks = OCB_MAX_BLOCKS - 1 + (ctx->message_count & 1);
-      ocb_fill_n (ctx, key, blocks, o);
+      ocb_fill_n (key, &ctx->offset, ctx->message_count, blocks, o);
+      ctx->message_count += n;
 
       size = blocks * OCB_BLOCK_SIZE;
       memxor3 (block[0].b, o[0].b, src, size);
@@ -223,7 +248,9 @@ ocb_crypt_n (struct ocb_ctx *ctx, const struct ocb_key *key,
 
       n -= blocks; src += size; dst -= size;
     }
-  ocb_fill_n (ctx, key, n, o);
+  ocb_fill_n (key, &ctx->offset, ctx->message_count, n, o);
+  ctx->message_count += n;
+
   size = n * OCB_BLOCK_SIZE;
   memxor3 (block[0].b, o[0].b, src, size);
   f (cipher, size, block[0].b, block[0].b);