原文链接：http://joelinoff.com/blog/?p=885
这里的示例显示了如何使用python以与openssl aes-256-cbc完全兼容的方式加密和解密数据。它是基于我在本网站上发布的C ++ Cipher类中所做的工作。它适用于python-2.7和python-3.x。
关键思想是基于openssl生成密钥和iv密码的数据以及它使用的“Salted__”前缀的方式。
因为我也掌握openssl的内部细节，所以先留着，等以后要是遇到需要了，在研究
使用方法
代码：
#!/usr/bin/env python ''' Implement openssl compatible AES-256 CBC mode encryption/decryption. This module provides encrypt() and decrypt() functions that are compatible with the openssl algorithms. This is basically a python encoding of my C++ work on the Cipher class using the Crypto.Cipher.AES class. URL: http://projects.joelinoff.com/cipher-1.1/doxydocs/html/ ''' # LICENSE # # MIT Open Source # # Copyright (c) 2014 Joe Linoff # # Permission is hereby granted, free of charge, to any person # obtaining a copy of this software and associated documentation files # (the "Software"), to deal in the Software without restriction, # including without limitation the rights to use, copy, modify, merge, # publish, distribute, sublicense, and/or sell copies of the Software, # and to permit persons to whom the Software is furnished to do so, # subject to the following conditions: # # The above copyright notice and this permission notice shall be # included in all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE # SOFTWARE. import argparse import base64 import os import re import hashlib import inspect import sys from getpass import getpass from Crypto.Cipher import AES VERSION='1.2' # ================================================================ # debug # ================================================================ def _debug(msg, lev=1): ''' Print a debug message with some context. ''' sys.stderr.write('DEBUG:{} ofp {} '.format(inspect.stack()[lev][2], msg)) # ================================================================ # get_key_and_iv # ================================================================ def get_key_and_iv(password, salt, klen=32, ilen=16, msgdgst='md5'): ''' Derive the key and the IV from the given password and salt. This is a niftier implementation than my direct transliteration of the C++ code although I modified to support different digests. CITATION: http://stackoverflow.com/questions/13907841/implement-openssl-aes-encryption-in-python @param password The password to use as the seed. @param salt The salt. @param klen The key length. @param ilen The initialization vector length. @param msgdgst The message digest algorithm to use. ''' # equivalent to: # from hashlib import <mdi> as mdf # from hashlib import md5 as mdf # from hashlib import sha512 as mdf mdf = getattr(__import__('hashlib', fromlist=[msgdgst]), msgdgst) password = password.encode('ascii', 'ignore') # convert to ASCII try: maxlen = klen + ilen keyiv = mdf(password + salt).digest() tmp = [keyiv] while len(tmp) < maxlen: tmp.append( mdf(tmp[-1] + password + salt).digest() ) keyiv += tmp[-1] # append the last byte key = keyiv[:klen] iv = keyiv[klen:klen+ilen] return key, iv except UnicodeDecodeError: return None, None # ================================================================ # encrypt # ================================================================ def encrypt(password, plaintext, chunkit=True, msgdgst='md5'): ''' Encrypt the plaintext using the password using an openssl compatible encryption algorithm. It is the same as creating a file with plaintext contents and running openssl like this: $ cat plaintext <plaintext> $ openssl enc -e -aes-256-cbc -base64 -salt \ -pass pass:<password> -n plaintext @param password The password. @param plaintext The plaintext to encrypt. @param chunkit Flag that tells encrypt to split the ciphertext into 64 character (MIME encoded) lines. This does not affect the decrypt operation. @param msgdgst The message digest algorithm. ''' salt = os.urandom(8) key, iv = get_key_and_iv(password, salt, msgdgst=msgdgst) if key is None: return None # PKCS#7 padding padding_len = 16 - (len(plaintext) % 16) if isinstance(plaintext, str): padded_plaintext = plaintext + (chr(padding_len) * padding_len) else: # assume bytes padded_plaintext = plaintext + (bytearray([padding_len] * padding_len)) # Encrypt cipher = AES.new(key, AES.MODE_CBC, iv) ciphertext = cipher.encrypt(padded_plaintext) # Make openssl compatible. # I first discovered this when I wrote the C++ Cipher class. # CITATION: http://projects.joelinoff.com/cipher-1.1/doxydocs/html/ openssl_ciphertext = b'Salted__' + salt + ciphertext b64 = base64.b64encode(openssl_ciphertext) if not chunkit: return b64 LINELEN = 64 chunk = lambda s: b' '.join(s[i:min(i+LINELEN, len(s))] for i in range(0, len(s), LINELEN)) return chunk(b64) # ================================================================ # decrypt # ================================================================ def decrypt(password, ciphertext, msgdgst='md5'): ''' Decrypt the ciphertext using the password using an openssl compatible decryption algorithm. It is the same as creating a file with ciphertext contents and running openssl like this: $ cat ciphertext # ENCRYPTED <ciphertext> $ egrep -v '^#|^$' | \ openssl enc -d -aes-256-cbc -base64 -salt -pass pass:<password> -in ciphertext @param password The password. @param ciphertext The ciphertext to decrypt. @param msgdgst The message digest algorithm. @returns the decrypted data. ''' # unfilter -- ignore blank lines and comments if isinstance(ciphertext, str): filtered = '' nl = ' ' re1 = r'^s*$' re2 = r'^s*#' else: filtered = b'' nl = b' ' re1 = b'^\s*$' re2 = b'^\s*#' for line in ciphertext.split(nl): line = line.strip() if re.search(re1,line) or re.search(re2, line): continue filtered += line + nl # Base64 decode raw = base64.b64decode(filtered) assert(raw[:8] == b'Salted__' ) salt = raw[8:16] # get the salt # Now create the key and iv. key, iv = get_key_and_iv(password, salt, msgdgst=msgdgst) if key is None: return None # The original ciphertext ciphertext = raw[16:] # Decrypt cipher = AES.new(key, AES.MODE_CBC, iv) padded_plaintext = cipher.decrypt(ciphertext) if isinstance(padded_plaintext, str): padding_len = ord(padded_plaintext[-1]) else: padding_len = padded_plaintext[-1] plaintext = padded_plaintext[:-padding_len] return plaintext # include the code above ... # ================================================================ # _open_ios # ================================================================ def _open_ios(args): ''' Open the IO files. ''' ifp = sys.stdin ofp = sys.stdout if args.input is not None: try: ifp = open(args.input, 'rb') except IOError: print('ERROR: cannot read file: {}'.format(args.input)) sys.exit(1) if args.output is not None: try: ofp = open(args.output, 'wb') except IOError: print('ERROR: cannot write file: {}'.format(args.output)) sys.exit(1) return ifp, ofp # ================================================================ # _close_ios # ================================================================ def _close_ios(ifp, ofp): ''' Close the IO files if necessary. ''' if ifp != sys.stdin: ifp.close() if ofp != sys.stdout: ofp.close() # ================================================================ # _write # ================================================================ def _write(ofp, out, newline=False): ''' Write out the data in the correct format. ''' if ofp == sys.stdout and isinstance(out, bytes): out = out.decode('utf-8', 'ignored') ofp.write(out) if newline: ofp.write(' ') elif isinstance(out, str): ofp.write(out) if newline: ofp.write(' ') else: # assume bytes ofp.write(out) if newline: ofp.write(b' ') # ================================================================ # _write # ================================================================ def _read(ifp): ''' Read the data in the correct format. ''' return ifp.read() # ================================================================ # _runenc # ================================================================ def _runenc(args): ''' Encrypt data. ''' if args.passphrase is None: while True: passphrase = getpass('Passphrase: ') tmp = getpass('Re-enter passphrase: ') if passphrase == tmp: break print('') print('Passphrases do not match, please try again.') else: passphrase = args.passphrase ifp, ofp = _open_ios(args) text = _read(ifp) out = encrypt(passphrase, text, msgdgst=args.msgdgst) _write(ofp, out, True) _close_ios(ifp, ofp) # ================================================================ # _rundec # ================================================================ def _rundec(args): ''' Decrypt data. ''' if args.passphrase is None: passphrase = getpass('Passphrase: ') else: passphrase = args.passphrase ifp, ofp = _open_ios(args) text = _read(ifp) out = decrypt(passphrase, text, msgdgst=args.msgdgst) _write(ofp, out, False) _close_ios(ifp, ofp) # ================================================================ # _runtest # ================================================================ def _runtest(args): ''' Run a series of iteration where each iteration generates a random password from 8-32 characters and random text from 20 to 256 characters. The encrypts and decrypts the random data. It then compares the results to make sure that everything works correctly. The test output looks like this: $ crypt 2000 2000 of 2000 100.00% 15 139 2000 0 $ # ^ ^ ^ ^ ^ ^ $ # | | | | | +-- num failed $ # | | | | +---------- num passed $ # | | | +-------------- size of text for a test $ # | | +----------------- size of passphrase for a test $ # | +-------------------------- percent completed $ # +------------------------------- total # #+------------------------------------ current test @param args The args parse arguments. ''' import string import random from random import randint # Encrypt/decrypt N random sets of plaintext and passwords. num = args.test ofp = sys.stdout if args.output is not None: try: ofp = open(args.output, 'w') except IOError: print('ERROR: can open file for writing: {}'.format(args.output)) sys.exit(1) chset = string.printable passed = 0 failed = [] maxlen = len(str(num)) for i in range(num): ran1 = randint(8,32) password = ''.join(random.choice(chset) for x in range(ran1)) ran2 = randint(20, 256) plaintext = ''.join(random.choice(chset) for x in range(ran2)) ciphertext = encrypt(password, plaintext, msgdgst=args.msgdgst) verification = decrypt(password, ciphertext, msgdgst=args.msgdgst) if plaintext != verification: failed.append( [password, plaintext] ) else: passed += 1 output = '%*d of %d %6.2f%% %3d %3d %*d %*d %s' % (maxlen,i+1, num, 100*(i+1)/num, len(password), len(plaintext), maxlen, passed, maxlen, len(failed), args.msgdgst) if args.output is None: ofp.write(''*80) ofp.write(output) ofp.flush() else: ofp.write(output+' ') ofp.write(' ') if len(failed): for i in range(len(failed)): ofp.write('%3d %2d %-34s %3d %s ' % (i, len(failed[i][0]), '"'+failed[i][0]+'"', len(failed[i][1]), '"'+failed[i][1]+'"')) ofp.write(' ') if args.output is not None: ofp.close() # ================================================================ # _cli_opts # ================================================================ def _cli_opts(): ''' Parse command line options. @returns the arguments ''' mepath = os.path.abspath(sys.argv[0]).encode('utf-8') mebase = os.path.basename(mepath) description = ''' Implements encryption/decryption that is compatible with openssl AES-256 CBC mode. You can use it as follows: EXAMPLE 1: {0} -> {0} (MD5) $ # Encrypt and decrypt using {0}. $ echo 'Lorem ipsum dolor sit amet' | \ {0} -e -p secret | \ {0} -d -p secret Lorem ipsum dolor sit amet EXAMPLE 2: {0} -> openssl (MD5) $ # Encrypt using {0} and decrypt using openssl. $ echo 'Lorem ipsum dolor sit amet' | \ {0} -e -p secret | \ openssl enc -d -aes-256-cbc -md md5 -base64 -salt -pass pass:secret Lorem ipsum dolor sit amet EXAMPLE 3: openssl -> {0} (MD5) $ # Encrypt using openssl and decrypt using {0} $ echo 'Lorem ipsum dolor sit amet' | \ openssl enc -e -aes-256-cbc -md md5 -base64 -salt -pass pass:secret {0} -d -p secret Lorem ipsum dolor sit amet EXAMPLE 4: openssl -> openssl (MD5) $ # Encrypt and decrypt using openssl $ echo 'Lorem ipsum dolor sit amet' | \ openssl enc -e -aes-256-cbc -md md5 -base64 -salt -pass pass:secret openssl enc -d -aes-256-cbc -md md5 -base64 -salt -pass pass:secret Lorem ipsum dolor sit amet EXAMPLE 5: {0} -> {0} (SHA512) $ # Encrypt and decrypt using {0}. $ echo 'Lorem ipsum dolor sit amet' | \ {0} -e -m sha512 -p secret | \ {0} -d -m sha512 -p secret Lorem ipsum dolor sit amet EXAMPLE 6: {0} -> openssl (SHA512) $ # Encrypt using {0} and decrypt using openssl. $ echo 'Lorem ipsum dolor sit amet' | \ {0} -e -m sha512 -p secret | \ openssl enc -d -aes-256-cbc -md sha1=512 -base64 -salt -pass pass:secret Lorem ipsum dolor sit amet EXAMPLE 7: $ # Run internal tests. $ {0} -t 2000 2000 of 2000 100.00%% 21 104 2000 0 md5 $ # ^ ^ ^ ^ ^ ^ ^ $ # | | | | | | +- message digest $ # | | | | | +--- num failed $ # | | | | +----------- num passed $ # | | | +--------------- size of text for a test $ # | | +------------------ size of passphrase for a test $ # | +--------------------------- percent completed $ # +-------------------------------- total # #+------------------------------------- current test '''.format(mebase.decode('ascii', 'ignore')) parser = argparse.ArgumentParser(prog=mebase, formatter_class=argparse.RawDescriptionHelpFormatter, description=description, ) group = parser.add_mutually_exclusive_group(required=True) group.add_argument('-d', '--decrypt', action='store_true', help='decryption mode') group.add_argument('-e', '--encrypt', action='store_true', help='encryption mode') parser.add_argument('-i', '--input', action='store', help='input file, default is stdin') parser.add_argument('-m', '--msgdgst', action='store', default='md5', help='message digest (md5, sha, sha1, sha256, sha512), default is md5') parser.add_argument('-o', '--output', action='store', help='output file, default is stdout') parser.add_argument('-p', '--passphrase', action='store', help='passphrase for encrypt/decrypt operations') group.add_argument('-t', '--test', action='store', default=-1, type=int, help='test mode (TEST is an integer)') parser.add_argument('-v', '--verbose', action='count', help='the level of verbosity') parser.add_argument('-V', '--version', action='version', version='%(prog)s '+VERSION) args = parser.parse_args() return args # ================================================================ # main # ================================================================ def main(): args = _cli_opts() if args.test > 0: if args.input is not None: print('WARNING: input argument will be ignored.') if args.passphrase is not None: print('WARNING: passphrase argument will be ignored.') _runtest(args) elif args.encrypt: _runenc(args) elif args.decrypt: _rundec(args) # ================================================================ # MAIN # ================================================================ if __name__ == "__main__": main()