API Documentation

package

cryptomsg

A simple python package to encrypt and decrypt messages with AES CBC mode.

  • Author: Quan Lin
  • License: MIT
  • Requires: pyaes (a pure python AES implementation)
Examples 
>>> from cryptomsg import CryptoMsg
>>> message = b'YOUR MESSAGE'
>>> # Use default key and iv, not secure.
>>> CryptoMsg().encrypt_msg(message)
b"E\xa8\x02\x08\xa3+m\xce'1\xc2\x1c\xa3\xeb\x06\x05"
>>> CryptoMsg().decrypt_msg(_)
b'YOUR MESSAGE'
>>> # Only set key, and iv is the same as key.
>>> CryptoMsg(b'YOUR KEY').encrypt_msg(message)
b'o\x8e\xa8\x13\xda )\x10zS\xfd\xf5\xae\x90\x95\xfb'
>>> CryptoMsg(b'YOUR KEY').decrypt_msg(_)
b'YOUR MESSAGE'
>>> # Set both key and iv, strongest encryption.
>>> CryptoMsg(b'YOUR KEY', b'YOUR IV').encrypt_msg(message)
b'\xbflr\xf6\xae\xc1\xf9W\xfc\xcd&\xf3R\xd3\x8b\xde'
>>> CryptoMsg(b'YOUR KEY', b'YOUR IV').decrypt_msg(_)
b'YOUR MESSAGE'
Classes
  • CryptoMsg — A class to encrypt and decrypt messages with AES CBC mode.
Functions
  • pad_msg16(msg) (bytes) — Pad message with space to the nearest length of multiple of 16.
function

cryptomsg.pad_msg16(msg)

Pad message with space to the nearest length of multiple of 16.

Parameters
  • msg (bytes) — The original message.
Returns (bytes)

Padded message to the nearest length of multiple of 16.

class

cryptomsg.CryptoMsg(aes_cbc_key=b'aes_cbc_key', aes_cbc_iv=None)

A class to encrypt and decrypt messages with AES CBC mode.

Parameters
  • aes_cbc_key (bytes, optional) — The key for AES CBC mode. (default is b"aes_cbc_key")
  • aes_cbc_iv (bytes, optional) — The initialization vector for AES CBC mode. (default is None)
Attributes
  • aes_cbc_iv (bytes) — The initialization vector for AES CBC mode.
  • aes_cbc_key (bytes) — The key for AES CBC mode.
  • decrypt_msg(cipher) — Decrypt message.
  • encrypt_msg(msg) — Encrypt message.

Notes

Initialization options

  1. With default key and iv, not secure. CryptoMsg()
  2. Only set key, and iv is the same as key. CryptoMsg(b'YOUR KEY')
  3. Set both key and iv, strongest encryption. CryptoMsg(b'YOUR KEY', b'YOUR IV')

The given key is padded with space to 16 bytes (if shorter than 16 bytes) or padded with space to 32 bytes (if length is between 16 and 32) or truncated to 32 bytes (if longer than 32 bytes). The given iv is padded with space or truncated to 16 bytes.

Methods
method
encrypt_msg(msg)

Encrypt message.

Parameters
  • msg (bytes) — The original message.
Returns (bytes)

The encrypted message.

method
decrypt_msg(cipher)

Decrypt message.

Parameters
  • cipher (bytes) — The encrypted message.
Returns (bytes)

The decrypted message.