Diff: crypto/crypto_aes_128_cbc.c

Revision:

4:cbaf466d717d

Parent:

2:527a66d0a1a9

diff -r eb324ffffd2b -r cbaf466d717d crypto/crypto_aes_128_cbc.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/crypto/crypto_aes_128_cbc.c	Tue Jun 10 14:23:09 2014 +0000
@@ -0,0 +1,103 @@
+/*
+MiniTLS - A super trimmed down TLS/SSL Library for embedded devices
+Author: Donatien Garnier
+Copyright (C) 2013-2014 AppNearMe Ltd
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+*//**
+ * \file crypto_aes_128_cbc.c
+ * \copyright Copyright (c) AppNearMe Ltd 2013
+ * \author Donatien Garnier
+ */
+
+#define __DEBUG__ 0
+#ifndef __MODULE__
+#define __MODULE__ "crypto_aes_128_cbc.c"
+#endif
+
+
+#include "core/fwk.h"
+#include "inc/minitls_errors.h"
+
+#include "crypto_aes_128_cbc.h"
+
+minitls_err_t crypto_aes_128_cbc_encrypt(crypto_aes_128_t* cipher, buffer_t* initialization_vector, buffer_t* buffer)
+{
+  uint8_t* text = buffer_current_read_position(buffer);
+  size_t size = buffer_length(buffer);
+
+  uint8_t* previous = buffer_current_read_position(initialization_vector);
+
+  if( (size % AES_128_BLOCK_SIZE) || (buffer_length(initialization_vector) != AES_128_BLOCK_SIZE) )
+  {
+    return MINITLS_ERR_WRONG_ALIGNMENT_FOR_CIPHER;
+  }
+
+  uint8_t xored_input[AES_128_BLOCK_SIZE]; //Xored input
+
+  while(size > 0)
+  {
+    for(int i = 0; i < AES_128_BLOCK_SIZE / sizeof(uint32_t); i++)
+    {
+      ((uint32_t*)xored_input)[i] = ((uint32_t*)previous)[i] ^ ((uint32_t*)text)[i];
+    }
+
+    crypto_aes_128_encrypt(cipher, xored_input, text);
+
+    previous = text; //Save previous ciphertext to use as initialization vector
+
+    text += AES_128_BLOCK_SIZE;
+    size -= AES_128_BLOCK_SIZE;
+  }
+
+  return MINITLS_OK;
+}
+
+minitls_err_t crypto_aes_128_cbc_decrypt(crypto_aes_128_t* cipher, buffer_t* initialization_vector, buffer_t* buffer)
+{
+  uint8_t* text = buffer_current_read_position(buffer);
+  size_t size = buffer_length(buffer);
+
+  if( (size % AES_128_BLOCK_SIZE) || (buffer_length(initialization_vector) != AES_128_BLOCK_SIZE) )
+  {
+    return MINITLS_ERR_WRONG_ALIGNMENT_FOR_CIPHER;
+  }
+
+  uint8_t xored_output[AES_128_BLOCK_SIZE]; //Xored input
+  uint8_t previous[AES_128_BLOCK_SIZE*2];
+
+  memcpy(previous, buffer_current_read_position(initialization_vector), AES_128_BLOCK_SIZE);
+
+  while(size > 0)
+  {
+    //Save cipher text (to use as initialization vector)
+    memcpy(previous + AES_128_BLOCK_SIZE, text, AES_128_BLOCK_SIZE);
+
+    crypto_aes_128_decrypt(cipher, text, xored_output);
+
+    for(int i = 0; i < AES_128_BLOCK_SIZE / sizeof(uint32_t); i++)
+    {
+      ((uint32_t*)text)[i] = ((uint32_t*)previous)[i] ^ ((uint32_t*)xored_output)[i];
+    }
+
+    memmove(previous, previous + AES_128_BLOCK_SIZE, AES_128_BLOCK_SIZE);
+
+    text += AES_128_BLOCK_SIZE;
+    size -= AES_128_BLOCK_SIZE;
+  }
+
+  return MINITLS_OK;
+}
+