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oscrypto.symmetric API Documentation

The oscrypto.symmetric submodule implements symmetric/secret key encryption and decryption. The following functions comprise the public API:

aes_cbc_pkcs7_encrypt() function

def aes_cbc_pkcs7_encrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string either 16, 24 or 32 bytes long

    :param data:
        The plaintext - a byte string

    :param iv:
        The initialization vector - either a byte string 16-bytes long or None
        to generate an IV

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A tuple of two byte strings (iv, ciphertext)
    """

Encrypts plaintext using AES in CBC mode with a 128, 192 or 256 bit key and PKCS#7 padding.

aes_cbc_pkcs7_decrypt() function

def aes_cbc_pkcs7_decrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string either 16, 24 or 32 bytes long

    :param data:
        The ciphertext - a byte string

    :param iv:
        The initialization vector - a byte string 16-bytes long

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A byte string of the plaintext
    """

Decrypts AES ciphertext in CBC mode using a 128, 192 or 256 bit key

aes_cbc_no_padding_encrypt() function

def aes_cbc_no_padding_encrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string either 16, 24 or 32 bytes long

    :param data:
        The plaintext - a byte string

    :param iv:
        The initialization vector - either a byte string 16-bytes long or None
        to generate an IV

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A tuple of two byte strings (iv, ciphertext)
    """

Encrypts plaintext using AES in CBC mode with a 128, 192 or 256 bit key and no padding. This means the ciphertext must be an exact multiple of 16 bytes long.

aes_cbc_no_padding_decrypt() function

def aes_cbc_no_padding_decrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string either 16, 24 or 32 bytes long

    :param data:
        The ciphertext - a byte string

    :param iv:
        The initialization vector - a byte string 16-bytes long

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A byte string of the plaintext
    """

Decrypts AES ciphertext in CBC mode using a 128, 192 or 256 bit key and no padding.

tripledes_cbc_pkcs5_encrypt() function

def tripledes_cbc_pkcs5_encrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string 16 or 24 bytes long (2 or 3 key mode)

    :param data:
        The plaintext - a byte string

    :param iv:
        The initialization vector - a byte string 8-bytes long or None
        to generate an IV

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A tuple of two byte strings (iv, ciphertext)
    """

Encrypts plaintext using 3DES in CBC mode using either the 2 or 3 key variant (16 or 24 byte long key) and PKCS#5 padding.

tripledes_cbc_pkcs5_decrypt() function

def tripledes_cbc_pkcs5_decrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string 16 or 24 bytes long (2 or 3 key mode)

    :param data:
        The ciphertext - a byte string

    :param iv:
        The initialization vector - a byte string 8-bytes long

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A byte string of the plaintext
    """

Decrypts 3DES ciphertext in CBC mode using either the 2 or 3 key variant (16 or 24 byte long key) and PKCS#5 padding.

des_cbc_pkcs5_encrypt() function

def des_cbc_pkcs5_encrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string 8 bytes long (includes error correction bits)

    :param data:
        The plaintext - a byte string

    :param iv:
        The initialization vector - a byte string 8-bytes long or None
        to generate an IV

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A tuple of two byte strings (iv, ciphertext)
    """

Encrypts plaintext using DES in CBC mode with a 56 bit key and PKCS#5 padding.

des_cbc_pkcs5_decrypt() function

def des_cbc_pkcs5_decrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string 8 bytes long (includes error correction bits)

    :param data:
        The ciphertext - a byte string

    :param iv:
        The initialization vector - a byte string 8-bytes long

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A byte string of the plaintext
    """

Decrypts DES ciphertext in CBC mode using a 56 bit key and PKCS#5 padding.

rc4_encrypt() function

def rc4_encrypt(key, data):
    """
    :param key:
        The encryption key - a byte string 5-16 bytes long

    :param data:
        The plaintext - a byte string

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A byte string of the ciphertext
    """

Encrypts plaintext using RC4 with a 40-128 bit key

rc4_decrypt() function

def rc4_decrypt(key, data):
    """
    :param key:
        The encryption key - a byte string 5-16 bytes long

    :param data:
        The ciphertext - a byte string

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A byte string of the plaintext
    """

Decrypts RC4 ciphertext using a 40-128 bit key

rc2_cbc_pkcs5_encrypt() function

def rc2_cbc_pkcs5_encrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string 8 bytes long

    :param data:
        The plaintext - a byte string

    :param iv:
        The initialization vector - a byte string 8-bytes long or None
        to generate an IV

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A tuple of two byte strings (iv, ciphertext)
    """

Encrypts plaintext using RC2 in CBC mode with a 40-128 bit key and PKCS#5 padding.

rc2_cbc_pkcs5_decrypt() function

def rc2_cbc_pkcs5_decrypt(key, data, iv):
    """
    :param key:
        The encryption key - a byte string 8 bytes long

    :param data:
        The ciphertext - a byte string

    :param iv:
        The initialization vector - a byte string 8 bytes long

    :raises:
        ValueError - when any of the parameters contain an invalid value
        TypeError - when any of the parameters are of the wrong type
        OSError - when an error is returned by the OS crypto library

    :return:
        A byte string of the plaintext
    """

Decrypts RC2 ciphertext ib CBC mode using a 40-128 bit key and PKCS#5 padding.