Python中RSA PKCS1_v1_5加解密加签

介绍

Python中实现RSA方式的加解密以及加签

依赖包

pycryptodome

加密加签

import base64
from Crypto.PublicKey import RSA
from Crypto.Hash import SHA256, MD5
from Crypto.Cipher import PKCS1_v1_5 as Cipher_pkcs1_v1_5
from Crypto.Signature import PKCS1_v1_5 as Signature_pkcs1_v1_5
import json
from copy import deepcopy
from collections import OrderedDict
from Crypto import Random

def rsa_pkcs1_encryptAndSign(thirdPublicKey, privateKey, requestJson):
    # 本例中，要加密的内容为 requestJson["bizContent"]
    # 加签后放在 requestJson["signContent"]
    # 用己方私钥加签（privateKey），第三方公钥加密（thirdPublicKey）　
    bizContent = json.dumps(requestJson["bizContent"])
    if "signContent" in requestJson.keys():
        del requestJson["signContent"]

    # 加密
    rsakey = RSA.importKey(base64.b64decode(thirdPublicKey))
    bizContent = bytes(bizContent, encoding="utf-8")
    cipher = Cipher_pkcs1_v1_5.new(rsakey)
    length = len(bizContent)
    default_length = 117
    offset = 0
    res = bytes()
    while length - offset > 0:
        if length - offset > default_length:
            _res = cipher.encrypt(bizContent[offset:offset + default_length])
        else:
            _res = cipher.encrypt(bizContent[offset:])
        offset += default_length
        res += _res
    requestJson["bizContent"] = base64.b64encode(res).decode('utf-8')

    # 加签
    # 这一部分参考双方约定，下方模仿Java中的map方法
    order_request = deepcopy(requestJson)
    linkedmap = OrderedDict()
    linkedkeys = sorted(order_request.keys())
    for _key in linkedkeys:
        linkedmap[_key] = str(order_request[_key])
    
    sign_request = "{"
    for key, value in linkedmap.items():
        _k_v = "{}={}, ".format(key, value)
        sign_request += _k_v  
    sign_request = sign_request[:-2] + "}"
    
    rsaprivatekey = RSA.importKey(base64.b64decode(bytes(privateKey, encoding='utf-8')))
    signer = Signature_pkcs1_v1_5.new(rsaprivatekey)
    digest = MD5.new(bytes(sign_request, encoding='utf-8'))
    sign = base64.b64encode(signer.sign(digest))

    requestJson["signContent"] = sign.decode('utf-8')
    return requestJson

解密

def decryptByPrivateKey(bizcontent, privateKey):
    # 用己方私钥解密 privateKey
    # bizcontent 对应上方加密过程

    MAX_DECRYPT_BLOCK = 128
    bizcontent = base64.b64decode(bytes(bizcontent, encoding='utf-8'))
    privateKey = base64.b64decode(bytes(privateKey, encoding='utf-8'))
    privateKey = RSA.import_key(privateKey)
    dsize = SHA256.digest_size
    sentinel = Random.new().read(15 + dsize)
    cipher = Cipher_pkcs1_v1_5.new(privateKey)
    input_len = len(bizcontent)
    off_set = 0
    _bizcontent = bytes()
    while input_len - off_set > 0:
        if input_len - off_set > MAX_DECRYPT_BLOCK:
            _cache = cipher.decrypt(bizcontent[off_set:MAX_DECRYPT_BLOCK + off_set], sentinel)
        else:
            _cache = cipher.decrypt(bizcontent[off_set:], sentinel)
        off_set += MAX_DECRYPT_BLOCK
        _bizcontent += _cache

    return json.loads(_bizcontent.decode('utf-8'))