使用标准库在Python中进行私有/公共加密

Question

是否有一个模块,我的搜索无法发现,将允许编写如下代码？想要编写这样的代码的原因并不重要.我所追求的是一些代码,它有一个简单的API来生成公钥和私钥字节密钥,并使用这些密钥轻松编码和解码数据.

import module, os

method, bits, data = 'RSA', 1024, os.urandom(1024)
public, private = module.generate_keys(method, bits)

assert isinstance(public, bytes) and isinstance(private, bytes)
assert module.decode(module.encode(data, private), public) == data
assert module.decode(module.encode(data, public), private) == data

大多数似乎可用的东西需要下载一个包,并且只能在Python 2.x上运行.查找使用PEM文件或其他类型证书的库也很常见.我想避免处理这些文件,动态生成公钥和私钥,并快速处理内存中的数据.

Answer 1

公钥加密不在标准库中.虽然PyPi上有一些第三方库:

• PyCrypto
• RSA Python

如果你对它背后的数学感兴趣,Python可以很容易地进行实验:

code = pow(msg, 65537, 5551201688147)               # encode using a public key
plaintext = pow(code, 109182490673, 5551201688147)  # decode using a private key

密钥生成涉及更多一点.下面是如何使用urandom作为熵源在内存中进行密钥生成的简化示例.代码在Py2.6和Py3.x下运行:

import random

def gen_prime(N=10**8, bases=range(2,20000)):
    # XXX replace with a more sophisticated algorithm
    p = 1
    while any(pow(base, p-1, p) != 1 for base in bases):
        p = random.SystemRandom().randrange(N)
    return p

def multinv(modulus, value):
    '''Multiplicative inverse in a given modulus

        >>> multinv(191, 138)
        18
        >>> 18 * 138 % 191
        1

    '''
    # http://en.wikipedia.org/wiki/Extended_Euclidean_algorithm
    x, lastx = 0, 1
    a, b = modulus, value
    while b:
        a, q, b = b, a // b, a % b
        x, lastx = lastx - q * x, x
    result = (1 - lastx * modulus) // value
    return result + modulus if result < 0 else result

def keygen(N):
    '''Generate public and private keys from primes up to N.

        >>> pubkey, privkey = keygen(2**64)
        >>> msg = 123456789012345
        >>> coded = pow(msg, 65537, pubkey)
        >>> plain = pow(coded, privkey, pubkey)
        >>> assert msg == plain

    '''
    # http://en.wikipedia.org/wiki/RSA
    prime1 = gen_prime(N)
    prime2 = gen_prime(N)
    totient = (prime1 - 1) * (prime2 - 1)
    return prime1 * prime2, multinv(totient, 65537)