crypto.py 文件源码

def stretch(passw, iv1):

    # hash the external iv and the password 8192 times
    digest = iv1 + (16 * b"\x00")

    for i in range(8192):
        passHash = hashes.Hash(hashes.SHA256(), backend=default_backend())
        passHash.update(digest)
        passHash.update(bytes(passw, "utf_16_le"))
        digest = passHash.finalize()

    return digest


# encrypting function
# arguments:
# infile: plaintext file path
# outfile: ciphertext file path
# passw: encryption password
# bufferSize: encryption buffer size, must be a multiple of
#             AES block size (16)
#             using a larger buffer speeds up things when dealing
#             with big files