Python AES-CBC implementation using AES-ECB

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Python AES-CBC implementation using AES-ECB














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$begingroup$


I am looking for ways to make this code more "pythonic" and any issues with my implementation. This was designed to solve Crytopal's Challenge 10. This challenge involves recreating the AES-CBC cipher using a library-provided AES-ECB function.



from Cryptodome.Cipher import AES

def decrypt_aes_ecb(data, key):
cipher = AES.new(key, AES.MODE_ECB)
return cipher.decrypt(data)

def encrypt_aes_ecb(data, key):
cipher = AES.new(key, AES.MODE_ECB)
return cipher.encrypt(data)

def pkcs7(val, block_size=16):
remaining = block_size - len(val) % block_size
if remaining == block_size:
remaining = 16
ret = val + chr(remaining).encode() * remaining

return ret

def unpkcs7(val, block_size=16):
pad_amount = val[-1]
if pad_amount == 0:
raise Exception
for i in range(len(val) - 1, len(val) - (pad_amount + 1), -1):
if val[i] != pad_amount:
raise Exception
return val[:-pad_amount]

def decrypt_aes_cbc(data, key, iv = b'x00' * 16, pad=True):
prev_chunk = iv

decrypted = []

for i in range(0, len(data), 16):
chunk = data[i : i + 16]
decrypted += xor(decrypt_aes_ecb(chunk, key), prev_chunk)
prev_chunk = chunk

if pad:
return unpkcs7(bytes(decrypted))
return bytes(decrypted)

def encrypt_aes_cbc(data, key, iv = b'x00' * 16, pad=True):
if pad:
padded = pkcs7(data)
else:
padded = data

prev_chunk = iv

encrypted = []

for i in range(0, len(padded), 16):
chunk = padded[i : i + 16]
encrypted_block = encrypt_aes_ecb(xor(chunk, prev_chunk), key)
encrypted += encrypted_block
prev_chunk = encrypted_block

return bytes(encrypted)








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    0












    $begingroup$


    I am looking for ways to make this code more "pythonic" and any issues with my implementation. This was designed to solve Crytopal's Challenge 10. This challenge involves recreating the AES-CBC cipher using a library-provided AES-ECB function.



    from Cryptodome.Cipher import AES

    def decrypt_aes_ecb(data, key):
    cipher = AES.new(key, AES.MODE_ECB)
    return cipher.decrypt(data)

    def encrypt_aes_ecb(data, key):
    cipher = AES.new(key, AES.MODE_ECB)
    return cipher.encrypt(data)

    def pkcs7(val, block_size=16):
    remaining = block_size - len(val) % block_size
    if remaining == block_size:
    remaining = 16
    ret = val + chr(remaining).encode() * remaining

    return ret

    def unpkcs7(val, block_size=16):
    pad_amount = val[-1]
    if pad_amount == 0:
    raise Exception
    for i in range(len(val) - 1, len(val) - (pad_amount + 1), -1):
    if val[i] != pad_amount:
    raise Exception
    return val[:-pad_amount]

    def decrypt_aes_cbc(data, key, iv = b'x00' * 16, pad=True):
    prev_chunk = iv

    decrypted = []

    for i in range(0, len(data), 16):
    chunk = data[i : i + 16]
    decrypted += xor(decrypt_aes_ecb(chunk, key), prev_chunk)
    prev_chunk = chunk

    if pad:
    return unpkcs7(bytes(decrypted))
    return bytes(decrypted)

    def encrypt_aes_cbc(data, key, iv = b'x00' * 16, pad=True):
    if pad:
    padded = pkcs7(data)
    else:
    padded = data

    prev_chunk = iv

    encrypted = []

    for i in range(0, len(padded), 16):
    chunk = padded[i : i + 16]
    encrypted_block = encrypt_aes_ecb(xor(chunk, prev_chunk), key)
    encrypted += encrypted_block
    prev_chunk = encrypted_block

    return bytes(encrypted)








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    $endgroup$














      0












      0








      0





      $begingroup$


      I am looking for ways to make this code more "pythonic" and any issues with my implementation. This was designed to solve Crytopal's Challenge 10. This challenge involves recreating the AES-CBC cipher using a library-provided AES-ECB function.



      from Cryptodome.Cipher import AES

      def decrypt_aes_ecb(data, key):
      cipher = AES.new(key, AES.MODE_ECB)
      return cipher.decrypt(data)

      def encrypt_aes_ecb(data, key):
      cipher = AES.new(key, AES.MODE_ECB)
      return cipher.encrypt(data)

      def pkcs7(val, block_size=16):
      remaining = block_size - len(val) % block_size
      if remaining == block_size:
      remaining = 16
      ret = val + chr(remaining).encode() * remaining

      return ret

      def unpkcs7(val, block_size=16):
      pad_amount = val[-1]
      if pad_amount == 0:
      raise Exception
      for i in range(len(val) - 1, len(val) - (pad_amount + 1), -1):
      if val[i] != pad_amount:
      raise Exception
      return val[:-pad_amount]

      def decrypt_aes_cbc(data, key, iv = b'x00' * 16, pad=True):
      prev_chunk = iv

      decrypted = []

      for i in range(0, len(data), 16):
      chunk = data[i : i + 16]
      decrypted += xor(decrypt_aes_ecb(chunk, key), prev_chunk)
      prev_chunk = chunk

      if pad:
      return unpkcs7(bytes(decrypted))
      return bytes(decrypted)

      def encrypt_aes_cbc(data, key, iv = b'x00' * 16, pad=True):
      if pad:
      padded = pkcs7(data)
      else:
      padded = data

      prev_chunk = iv

      encrypted = []

      for i in range(0, len(padded), 16):
      chunk = padded[i : i + 16]
      encrypted_block = encrypt_aes_ecb(xor(chunk, prev_chunk), key)
      encrypted += encrypted_block
      prev_chunk = encrypted_block

      return bytes(encrypted)








      share







      New contributor




      Infuzion is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      $endgroup$




      I am looking for ways to make this code more "pythonic" and any issues with my implementation. This was designed to solve Crytopal's Challenge 10. This challenge involves recreating the AES-CBC cipher using a library-provided AES-ECB function.



      from Cryptodome.Cipher import AES

      def decrypt_aes_ecb(data, key):
      cipher = AES.new(key, AES.MODE_ECB)
      return cipher.decrypt(data)

      def encrypt_aes_ecb(data, key):
      cipher = AES.new(key, AES.MODE_ECB)
      return cipher.encrypt(data)

      def pkcs7(val, block_size=16):
      remaining = block_size - len(val) % block_size
      if remaining == block_size:
      remaining = 16
      ret = val + chr(remaining).encode() * remaining

      return ret

      def unpkcs7(val, block_size=16):
      pad_amount = val[-1]
      if pad_amount == 0:
      raise Exception
      for i in range(len(val) - 1, len(val) - (pad_amount + 1), -1):
      if val[i] != pad_amount:
      raise Exception
      return val[:-pad_amount]

      def decrypt_aes_cbc(data, key, iv = b'x00' * 16, pad=True):
      prev_chunk = iv

      decrypted = []

      for i in range(0, len(data), 16):
      chunk = data[i : i + 16]
      decrypted += xor(decrypt_aes_ecb(chunk, key), prev_chunk)
      prev_chunk = chunk

      if pad:
      return unpkcs7(bytes(decrypted))
      return bytes(decrypted)

      def encrypt_aes_cbc(data, key, iv = b'x00' * 16, pad=True):
      if pad:
      padded = pkcs7(data)
      else:
      padded = data

      prev_chunk = iv

      encrypted = []

      for i in range(0, len(padded), 16):
      chunk = padded[i : i + 16]
      encrypted_block = encrypt_aes_ecb(xor(chunk, prev_chunk), key)
      encrypted += encrypted_block
      prev_chunk = encrypted_block

      return bytes(encrypted)






      python python-3.x programming-challenge cryptography





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      asked 2 mins ago









      InfuzionInfuzion

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      Infuzion is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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