docs/development/custom-vectors/cast5/generate_cast5.py

# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.

from __future__ import absolute_import, division, print_function

import binascii

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.ciphers import algorithms, base, modes


def encrypt(mode, key, iv, plaintext):
    cipher = base.Cipher(
        algorithms.CAST5(binascii.unhexlify(key)),
        mode(binascii.unhexlify(iv)),
        default_backend(),
    )
    encryptor = cipher.encryptor()
    ct = encryptor.update(binascii.unhexlify(plaintext))
    ct += encryptor.finalize()
    return binascii.hexlify(ct)


def build_vectors(mode, filename):
    count = 0
    output = []
    key = None
    iv = None
    plaintext = None

    with open(filename, "r") as vector_file:
        for line in vector_file:
            line = line.strip()
            if line.startswith("KEY"):
                if count != 0:
                    output.append(
                        "CIPHERTEXT = {}".format(
                            encrypt(mode, key, iv, plaintext)
                        )
                    )
                output.append("\nCOUNT = {}".format(count))
                count += 1
                name, key = line.split(" = ")
                output.append("KEY = {}".format(key))
            elif line.startswith("IV"):
                name, iv = line.split(" = ")
                iv = iv[0:16]
                output.append("IV = {}".format(iv))
            elif line.startswith("PLAINTEXT"):
                name, plaintext = line.split(" = ")
                output.append("PLAINTEXT = {}".format(plaintext))
        output.append(
            "CIPHERTEXT = {}".format(encrypt(mode, key, iv, plaintext))
        )
    return "\n".join(output)


def write_file(data, filename):
    with open(filename, "w") as f:
        f.write(data)


cbc_path = "tests/hazmat/primitives/vectors/ciphers/AES/CBC/CBCMMT128.rsp"
write_file(build_vectors(modes.CBC, cbc_path), "cast5-cbc.txt")
ofb_path = "tests/hazmat/primitives/vectors/ciphers/AES/OFB/OFBMMT128.rsp"
write_file(build_vectors(modes.OFB, ofb_path), "cast5-ofb.txt")
cfb_path = "tests/hazmat/primitives/vectors/ciphers/AES/CFB/CFB128MMT128.rsp"
write_file(build_vectors(modes.CFB, cfb_path), "cast5-cfb.txt")
ctr_path = "tests/hazmat/primitives/vectors/ciphers/AES/CTR/aes-128-ctr.txt"
write_file(build_vectors(modes.CTR, ctr_path), "cast5-ctr.txt")