replaced twofish implementation by a faster version

src/tf.c

@@ -465,6 +465,7 @@ int tf_cbc_decrypt (unsigned char *out, const unsigned char *in, size_t in_len,
                     const unsigned char *iv, tf_context_t *ctx) {
 
   uint8_t tmp[TF_BLOCK_SIZE];
+  uint8_t old[TF_BLOCK_SIZE];
   size_t i;
   size_t n;
 
@@ -472,9 +473,10 @@ int tf_cbc_decrypt (unsigned char *out, const unsigned char *in, size_t in_len,
 
   n = in_len / TF_BLOCK_SIZE;
   for(i=0; i < n; i++) {
+    memcpy(old, &in[i * TF_BLOCK_SIZE], TF_BLOCK_SIZE);
     twofish_internal_decrypt(ctx->K, ctx->QF, &out[i * TF_BLOCK_SIZE], &in[i * TF_BLOCK_SIZE]);
     fix_xor(&out[i * TF_BLOCK_SIZE], tmp);
-    memcpy(tmp, &in[i * TF_BLOCK_SIZE], TF_BLOCK_SIZE);
+    memcpy(tmp, old, TF_BLOCK_SIZE);
   }
 
   return n * TF_BLOCK_SIZE;

src/transform_tf.c

@@ -29,7 +29,7 @@
 
 // cbc mode is being used with random value prepended to plaintext
 // instead of iv so, actual iv is null_iv
-uint8_t null_iv[TF_IV_SIZE] = {0};
+const uint8_t null_iv[TF_IV_SIZE] = {0};
 
 typedef struct transop_tf {
   tf_context_t       *ctx;
@@ -70,6 +70,7 @@ static int transop_encode_tf(n2n_trans_op_t * arg,
   // the assembly buffer is a source for encrypting data
   // the whole contents of assembly are encrypted
   uint8_t assembly[N2N_PKT_BUF_SIZE];
+  uint8_t assembly2[N2N_PKT_BUF_SIZE];
   size_t idx = 0;
   int padded_len;
   uint8_t padding;
@@ -83,10 +84,10 @@ static int transop_encode_tf(n2n_trans_op_t * arg,
         // full block sized random value (128 bit)
 	// !!! replace with 2 calls to encode_uint64(...) as as available
         // !!! which is still under consideration in pull request 'revAes'
-	encode_uint32(assembly, &idx, 0);
+	encode_uint32(assembly, &idx, n2n_rand());
-	encode_uint32(assembly, &idx, 0);
+	encode_uint32(assembly, &idx, n2n_rand());
-	encode_uint32(assembly, &idx, 0);
+	encode_uint32(assembly, &idx, n2n_rand());
-	encode_uint32(assembly, &idx, 0);
+	encode_uint32(assembly, &idx, n2n_rand());
 
         // adjust for maybe differently chosen TF_PREAMBLE_SIZE
         idx = TF_PREAMBLE_SIZE;
@@ -100,7 +101,6 @@ static int transop_encode_tf(n2n_trans_op_t * arg,
         // pad the following bytes with zero, fixed length (TF_BLOCK_SIZE) seems to compile
         // to slightly faster code than run-time dependant 'padding'
         memset (assembly + idx, 0, TF_BLOCK_SIZE);
-
         tf_cbc_encrypt(outbuf, assembly, padded_len, null_iv, priv->ctx);
 
         if(padding) {
@@ -156,7 +156,9 @@ static int transop_decode_tf(n2n_trans_op_t * arg,
       //  write new penultimate block from buf
       memcpy(assembly + penultimate_block, buf, TF_BLOCK_SIZE);
       // regular cbc decryption on the re-arranged ciphertext
+
       tf_cbc_decrypt(assembly, assembly, in_len + TF_BLOCK_SIZE - rest, null_iv, priv->ctx);
+
       // check for expected zero padding and give a warning otherwise
       if (memcmp(assembly + in_len, null_iv, TF_BLOCK_SIZE - rest)) {
         traceEvent(TRACE_WARNING, "transop_decode_tf payload decryption failed with unexpected cipher text stealing padding");