最近在做Web系统的一个license许可功能的时候遇到了一个问题，当我用RSA对获取到的系统的特征值进行加密解密时，由于特征值字符串过长，导致RSA加解密的时候提示文本过长，失败。因此这里记录下我封装的对于长文本，RSA加解密的一个类。

提前准备好公钥和私钥文件.
公钥和私钥文件生成见文章Python生成RSA公钥public.pem私钥private.pem 

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from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_v1_5 as Cipher_pkcs1_v1_5
import base64


long_text = "helloworld......"  # 可自行加长补全


class RSAsys:
    public_pem = './public.pem'
    private_pem = './private.pem'

    # 加密
    @classmethod
    def rsa_encrypt(cls, message, p_length=200):
        rsakey = RSA.importKey(open(cls.public_pem).read())
        cipher = Cipher_pkcs1_v1_5.new(rsakey)  # 创建用于执行pkcs1_v1_5加密或解密的密码
        res = []
        for i in range(0, len(message), p_length):
            res.append(cipher.encrypt(message[i:i+p_length].encode()))
        cipher_text_byte = b''
        for b in res:
            cipher_text_byte += b
        cipher_text = base64.b64encode(cipher_text_byte)
        return cipher_text.decode('utf-8')

    # 解密
    @classmethod
    def rsa_decrypt(cls, cipher_text, p_length=256):
        encrypt_text = base64.b64decode(cipher_text.encode('utf-8'))
        rsakey = RSA.importKey(open(cls.private_pem).read())
        cipher = Cipher_pkcs1_v1_5.new(rsakey)  # 创建用于执行pkcs1_v1_5加密或解密的密码
        res = []
        for i in range(0, len(encrypt_text), p_length):
            res.append(cipher.decrypt(encrypt_text[i:i+p_length], "解密失败"))
        text = b''
        for b in res:
            text += b
        return text.decode('utf-8')


if __name__ == '__main__':
    en_text = RSAsys.rsa_encrypt(long_text)
    print(en_text)
    de_text = RSAsys.rsa_decrypt(en_text)
    print(de_text)