symmetric.py

Contains functions for symmetric encryption/decryption, by default with AES_256_CBC although this can be set to an other encryption algorithm or key length in a later stage.

Note

The encrypted values are returned with the cipher prepended, as following: AES256CBC$encrypted_value

Class and function definitions:

exception core.encryption.symmetric.EncryptionException

Bases: exceptions.Exception

This exception is thrown when the cipher is unknown.

core.encryption.symmetric.get_max_length(max_length, cipher=<class core.encryption.AES.AES_256_CBC>)

Get the max_length to set on a field based on the max_length you want to store on the field..

Args:

• max_length: the max_length of the text to store
• cipher: override the default cipher

Returns:

The max length of the field to hold the AES encryption. based on the first: 2 ^ x which is high enough.

Raises:

EncryptionException: Cipher is unknown

core.encryption.symmetric.is_encrypted(value)

Check if the value is encrypted by comparing the first characters of the value to the list of known ciphers.

Args:

• value: the value to check (AES256CBC$#encrypted_value#)

Returns:

True if the cipher name could be found in the value else False

core.encryption.symmetric.encrypt(plain_text, key, cipher=default_cipher)

Encrypt wrapper function

Args:

• plain_text: the text to encrypt
• key: the key to use
• cipher: override the default cipher

Returns:

encrypted plain_text by key with use of cipher

Raises:

EncryptionException: Cipher is unknown

core.encryption.symmetric.decrypt(cipher_and_encrypted_text, key)

Decrypt wrapper function

the cipher_and_encrypted_text in ciphername$encrypted_text format with use of the key

Args:

• cipher_and_encrypted_text: encrypted value in ciphername$encrypted_text
• key: the key to use

Returns:

plain text if key is correct else crap.

Raises:

EncryptionException: Cipher is unknown