old_contents: # Author: Trevor Perrin
  # See the LICENSE file for legal information regarding use of this file.
  
  """Pure-Python AES implementation."""
  
  from .cryptomath import *
  
  from .aes import *
  from .rijndael import rijndael
  
  def new(key, mode, IV):
      return Python_AES(key, mode, IV)
  
  class Python_AES(AES):
      def __init__(self, key, mode, IV):
          AES.__init__(self, key, mode, IV, "python")
          self.rijndael = rijndael(key, 16)
          self.IV = IV
  
      def encrypt(self, plaintext):
          AES.encrypt(self, plaintext)
  
          plaintextBytes = plaintext[:]
          chainBytes = self.IV[:]
  
          #CBC Mode: For each block...
          for x in range(len(plaintextBytes)//16):
  
              #XOR with the chaining block
              blockBytes = plaintextBytes[x*16 : (x*16)+16]
              for y in range(16):
                  blockBytes[y] ^= chainBytes[y]
  
              #Encrypt it
              encryptedBytes = self.rijndael.encrypt(blockBytes)
  
              #Overwrite the input with the output
              for y in range(16):
                  plaintextBytes[(x*16)+y] = encryptedBytes[y]
  
              #Set the next chaining block
              chainBytes = encryptedBytes
  
          self.IV = chainBytes[:]
          return plaintextBytes
  
      def decrypt(self, ciphertext):
          AES.decrypt(self, ciphertext)
  
          ciphertextBytes = ciphertext[:]
          chainBytes = self.IV[:]
  
          #CBC Mode: For each block...
          for x in range(len(ciphertextBytes)//16):
  
              #Decrypt it
              blockBytes = ciphertextBytes[x*16 : (x*16)+16]
              decryptedBytes = self.rijndael.decrypt(blockBytes)
  
              #XOR with the chaining block and overwrite the input with output
              for y in range(16):
                  decryptedBytes[y] ^= chainBytes[y]
                  ciphertextBytes[(x*16)+y] = decryptedBytes[y]
  
              #Set the next chaining block
              chainBytes = blockBytes
  
          self.IV = chainBytes[:]
          return ciphertextBytes
  
new_contents: # Author: Trevor Perrin
  # See the LICENSE file for legal information regarding use of this file.
  
  """Pure-Python AES implementation."""
  
  from .cryptomath import *
  import time
  
  from .aes import *
  from .rijndael import rijndael
  
  def new(key, mode, IV):
      return Python_AES(key, mode, IV)
  
  class Python_AES(AES):
      def __init__(self, key, mode, IV):
          AES.__init__(self, key, mode, IV, "python")
          self.rijndael = rijndael(key, 16)
          self.IV = IV
  
      def encrypt(self, plaintext):
          AES.encrypt(self, plaintext)
  
          plaintextBytes = plaintext[:]
          chainBytes = self.IV[:]
  
          encrypt = self.rijndael.encrypt
          
          starttime = time.clock()
          
          #CBC Mode: For each block...
          for x in xrange(len(plaintextBytes)//16):
   
              #XOR with the chaining block
              blockBytes = plaintextBytes[x*16 : (x*16)+16]
              for y in xrange(16):
                  blockBytes[y] ^= chainBytes[y]
                  
              #Encrypt it
              encryptedBytes = encrypt(blockBytes)
         
              #Overwrite the input with the output
              for y in xrange(16):
                  plaintextBytes[(x*16)+y] = encryptedBytes[y]
  
  
              #Set the next chaining block
              chainBytes = encryptedBytes
  
          self.IV = chainBytes[:]
  
          return plaintextBytes
  
      def decrypt(self, ciphertext):
          AES.decrypt(self, ciphertext)
  
          ciphertextBytes = ciphertext[:]
          chainBytes = self.IV[:]
  
  
          decrypt = self.rijndael.decrypt
                  
          #CBC Mode: For each block...
          for x in xrange(len(ciphertextBytes)//16):
  
              #Decrypt it
              blockBytes = ciphertextBytes[x*16 : (x*16)+16]
              decryptedBytes = decrypt(blockBytes)
  
              #XOR with the chaining block and overwrite the input with output
              for y in xrange(16):
                  decryptedBytes[y] ^= chainBytes[y]
                  ciphertextBytes[(x*16)+y] = decryptedBytes[y]
  
              #Set the next chaining block
              chainBytes = blockBytes
  
          self.IV = chainBytes[:]    
          
          return ciphertextBytes
  
subject: Update python_aes.py