ez_crypto module

class ez_crypto.CryptoBaseClass

Bases: object

Base class defining common functions.

attribute_setter(**kwargs)

Sets kwargs as instance attributes.

return_dict(return_list)

Extracts instance attributes into dictionary from return_list.

exception ez_crypto.PrivateKeyError(value)

Bases: exceptions.Exception

PrivateKeyError exception is raised if the private key is not found or corrupted.

exception ez_crypto.PublicKeyError(value)

Bases: exceptions.Exception

PublicKeyError exception is raised if the public key is not found or corrupted.

class ez_crypto.eZ_AES(plaintext=None, **kwargs)

Bases: ez_crypto.CryptoBaseClass

AES cipher object. Provides symmetric encryption. Requires plaintext string or ciphered dictionary object. Dictionary object must contain following keys: [‘iv’, ‘key’, ‘cipher’] Encryption parameters as of crypt_mode_1: keylength = 32 Bytes, padding = ‘
...’, AES cipher mode = Cipher Block Chain.

add_padding(text)

Pads text to whole blocks (AES blocksize = 16). Padding scheme is binary ‘100000...’. If message length is multiple of blocksize, a whole additional block will be padded.

decrypt()

Produces plaintext from ciphertext, if provided with correct key and encryption parameters.

encrypt()

Creates random IV (Injection Vector) and random symmetric key. Encrypts padded text. Returns dictionary with base64 encoded ciphertext, key, IV and the crypt_mode used.

hmac_digest(key, plaintext)

Returns the hexdigest of a message, if provided with key.

hmac_verify(key, plaintext, hexmac_to_verify)

Return bool. True if verification sucessfull, False otherwise.

remove_padding(text)

Unpads decrypted text. Removes rightmost zeros and one (interrupt) byte.

class ez_crypto.eZ_CryptoScheme(**kwargs)

Bases: ez_crypto.CryptoBaseClass

Outer crypto API to encrypt+sign and decrypt+verify message objects. Encryption must be provided as dictionary with following keys: [‘etime’, ‘sender’, ‘recipient’, ‘content’]

decrypt_verify()

Decrypt and unpack cipher block, check HMAC. Return HMAC check result in ‘authorized’ key, as well as the other plaintext attributes.

encrypt_sign()

Pack content, exact time and sender to plaintext block. Sign and encrypt plaintext block. Return crypto items as dictionary.

class ez_crypto.eZ_RSA

Bases: ez_crypto.CryptoBaseClass

RSA cipher object. Provides asymmetric encrytpion. Recommended minimal keylength: 2048 bit.

RSA_KEY_SIZE = 2048

decrypt(private_key, ciphertext)

RSA decrypt method, PKCS1_OAEP. (See PyCrypto documentation for further information.)

encrypt(public_key, plaintext)

RSA encrypt method, PKCS1_OAEP. (See PyCrypto documentation for further information.)

generate_keys(user, testing=False)

Create RSA keypair, return the exported public key, which will be stored in the database, and write the exported private key to disc.

get_private_key(user)

Import the senders keypair from Harddisk.

get_public_key(user)

Get recipient public key from database.

priv_key_loc(user)

Sets the path for the private keyfiles. Base path retrieved from the user preferences.

sign(private_key, plaintext)

Sign plaintext with private key.

verify(public_key, plaintext, signature)

Verify signature against plaintext with public key. Return True if successful, false otherwise.