Python PyCrypto(PyCryptodome) ASE实现对文件加密和解密方法

1、PyCryptodome的padding方法

pad和unpad函数是从Crypto.Util复制的。填充并修改为只使用PKCS7填充。注意，当使用PKCS7填充时，填充最后一个块是很重要的，即使它的大小是块大小的倍数，否则您将无法正确地解填充。

try:
    from Crypto.Util.Padding import pad, unpad
except ImportError:
    from Crypto.Util.py3compat import bchr, bord
    def pad(data_to_pad, block_size):
        padding_len = block_size-len(data_to_pad)%block_size
        padding = bchr(padding_len)*padding_len
        return data_to_pad + padding
    def unpad(padded_data, block_size):
        pdata_len = len(padded_data)
        if pdata_len % block_size:
            raise ValueError("Input data is not padded")
        padding_len = bord(padded_data[-1])
        if padding_len<1 or padding_len>min(block_size, pdata_len):
            raise ValueError("Padding is incorrect.")
        if padded_data[-padding_len:]!=bchr(padding_len)*padding_len:
            raise ValueError("PKCS#7 padding is incorrect.")
        return padded_data[:-padding_len]

2、文件加密和解密方法

1）加密方法代码

def encrypt_file(key, in_filename, out_filename=None, chunksize=64*1024):    if not out_filename:        out_filename = in_filename + '.enc'    iv = os.urandom(16)    encryptor = AES.new(key, AES.MODE_CBC, iv)    filesize = os.path.getsize(in_filename)    with open(in_filename, 'rb') as infile:        with open(out_filename, 'wb') as outfile:            outfile.write(struct.pack('
2)解密方法代码
def decrypt_file(key, in_filename, out_filename=None, chunksize=64*1024):    if not out_filename:        out_filename = in_filename + '.dec'    with open(in_filename, 'rb') as infile:        filesize = struct.unpack('
注意：上面代码与Python2/Python3兼容，它应该可以与PyCryptodome或PyCrypto一起使用。
但是，虽然本文介绍的是PyCrypto，还是建议您更新到PyCryptodome。PyCryptodome是PyCrypto的一个分支，它公开了相同的API(因此您不需要过多地更改代码)，还提供了一些额外的特性:填充函数、经过身份验证的加密算法、KDFs等。另一方面，PyCrypto不再被维护，而且一些版本还存在基于堆的缓冲区溢出漏洞。
安装PyCryptodome使用下面命令：
pip install PyCryptodome
3、完整代码
import os, random, structfrom Crypto.Cipher import AEStry:    from Crypto.Util.Padding import pad, unpadexcept ImportError:    from Crypto.Util.py3compat import bchr, bord    def pad(data_to_pad, block_size):        padding_len = block_size-len(data_to_pad)%block_size        padding = bchr(padding_len)*padding_len        return data_to_pad + padding    def unpad(padded_data, block_size):        pdata_len = len(padded_data)        if pdata_len % block_size:            raise ValueError("Input data is not padded")        padding_len = bord(padded_data[-1])        if padding_len<1 or padding_len>min(block_size, pdata_len):            raise ValueError("Padding is incorrect.")        if padded_data[-padding_len:]!=bchr(padding_len)*padding_len:            raise ValueError("PKCS#7 padding is incorrect.")        return padded_data[:-padding_len]def encrypt_file(key, in_filename, out_filename=None, chunksize=64*1024):    if not out_filename:        out_filename = in_filename + '.enc'    iv = os.urandom(16)    encryptor = AES.new(key, AES.MODE_CBC, iv)    filesize = os.path.getsize(in_filename)    with open(in_filename, 'rb') as infile:        with open(out_filename, 'wb') as outfile:            outfile.write(struct.pack('