mbed-os/targets/TARGET_Cypress/TARGET_PSOC6/sb-tools/imgtool/aes_cipher.py

122 lines
3.7 KiB
Python

# Copyright 2019 Cypress Semiconductor Corporation
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import click
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import padding
class AESCipher(object):
def __init__(self, key, IV):
self.backend = default_backend()
self.key = AESCipher.get_bytes(key)
self.iv = AESCipher.get_bytes(IV)
self.block_size = 128
@staticmethod
def get_bytes(inputdata):
if type(inputdata) is str:
return str.encode(inputdata,'utf-8')
elif type(inputdata) is bytes:
return inputdata
else:
raise Exception("Unknown input data type...")
class AESCipherCBC(AESCipher):
def __init__(self, key, IV):
super().__init__(key, IV)
self.cipher = Cipher(algorithms.AES(self.key), modes.CBC(self.iv), backend=self.backend)
def encrypt(self, raw):
encryptor = self.cipher.encryptor()
padder = padding.PKCS7(self.block_size).padder()
return encryptor.update(padder.update(raw) + padder.finalize()) + encryptor.finalize()
def decrypt(self, enc):
decryptor = self.cipher.decryptor()
unpadder = padding.PKCS7(self.block_size).unpadder()
return unpadder.update(decryptor.update(enc) + decryptor.finalize()) + unpadder.finalize()
class AESCipherGCM(AESCipher):
def __init__(self, key, IV, auth_data):
super().__init__(key, IV)
self.cipher = AESGCM(self.key)
self.auth_data = str.encode(auth_data,'utf-8')
def encrypt(self, raw):
return self.cipher.encrypt(self.iv, raw, self.auth_data)
def decrypt(self, enc):
return self.cipher.decrypt(self.iv, enc, self.auth_data)
def read_key_from_file(keyfile):
with open(keyfile) as f:
content = f.read().splitlines()
if len(content) < 2:
raise Exception("Not anough AES input data: in the file should be two lines: key, iv ...")
key = bytes.fromhex(content[0])
iv = bytes.fromhex(content[1])
if 8*len(key) not in set([128, 192, 256]):
raise Exception("Invalid AES Key length: should be 128, 192 or 256 bits")
check_iv_length(iv)
return key, iv
def check_iv_length(iv):
if 8*len(iv) != 128:
raise Exception("Invalid AES IV length: should be 128 bits")
return True
@click.command()
@click.option('-k', '--keyfile')
@click.option('-a', '--auth_data', default='default data')
@click.option('-m', '--mode', default='CBC')
@click.argument('inputfile')
@click.argument('outputfile')
def main(keyfile, auth_data, mode, inputfile, outputfile):
key, iv = read_key_from_file(keyfile)
if mode == 'CBC':
check_iv_length(iv)
aes = AESCipherCBC(key, iv)
elif mode == 'GCM':
aes = AESCipherGCM(key, iv, auth_data)
else:
raise Exception("Selected mode is not supported...")
inFile = open(inputfile,"rb")
outFile = open(outputfile,"wb")
outFile.write(aes.encrypt(inFile.read()))
inFile.close()
outFile.close()
if __name__ == "__main__":
main()