magicandy 2020-01-02
1、简单介绍:
RSA加密算法是一种非对称加密算法 是由已知加密密钥推导出解密密钥在计算上是不可行的”密码体制。加密密钥(即公开密钥)PK是公开信息,而解密密钥(即秘密密钥)SK是需要保密的。
RSA密钥至少为500位长,一般推荐使用1024位。RSA密钥长度随着保密级别提高,增加很快。
由于RSA的特性,一个1024位的密钥只能加密117位字节数据,当数据量超过117位字节的时候,程序就会抛出异常。 ——来自大佬
2、代码实现:
来一段大佬的代码:
import rsa # 一、生成公钥及私钥, 并保存 public_key, private_key = rsa.newkeys(1024) # 生成公钥和私钥 # 将生成的公钥和私钥进行转换,以便存储 pub = public_key.save_pkcs1() pri = private_key.save_pkcs1('PEM') # save_pkcsl()是内置方法,其默认参数是‘PEM’ with open('pubkey.pem', mode='wb') as f, open('privkey.pem', mode='wb') as f1: f.write(pub) # 打开两个文件,分别存储公钥及私钥 f1.write(pri) # 二. 使用公钥加密, 私钥解密 def func(): with open('pubkey.pem', mode='rb') as f, open('privkey.pem', 'rb') as f1: pub = f.read() # 从文件中再读出公钥和私钥 pri = f1.read() public_key = rsa.PublicKey.load_pkcs1(pub) # 转换为原始状态 private_key = rsa.PrivateKey.load_pkcs1(pri) message = "rsa加密测试" info = rsa.encrypt(message.encode('utf-8'), public_key) # 使用公钥加密内容,内容必须是二进制 msg = rsa.decrypt(info, private_key) # 使用私钥解密,获得解密后的内容 print(msg.decode('utf-8')) # 使用之前记得先解码
3、代码升级:
现在我将上述的代码段封装成一个Rsa class(包含的方法有:__init__
——初始化方法,key_transform_store
——存储公钥与私钥的方法、encry
——加密方法、decry
——解密方法),使用的时候,直接将下面的代码段拎到我们需要的地方去引用:先创建一Rsa对象,然后调用里面的方法即可:
import rsa class Rsa(object): """RSA加密、解密""" def __init__(self, number, pub_path='public_key.pem', priv_path='private_key.pem'): """ :param pub_path: the path to public key, default its path is public_key.pem :param priv_path: the path to private key, default its path is private_key.pem """ # Generate the public and private keys, and returns them self.public_key, self.private_key = rsa.newkeys(number) self.public_key_path = pub_path self.private_key_path = priv_path def key_transform_store(self): """ convert and save the generated public and private keys to a file :return: None """ # convert the generated public and private keys for storage pub = self.public_key.save_pkcs1() pri = self.private_key.save_pkcs1('PEM') # open two files to store the public key and private key respectively with open(self.public_key_path, mode='wb') as f: f.write(pub) with open(self.private_key_path, mode='wb') as f1: f1.write(pri) def encry(self, info): """ encrypt information :param info: the original string information to be encrypted :return:info_encrypted """ # read the public key from the file with open(self.public_key_path, mode='rb') as f: pub = f.read() # convert pub to original state public_key = rsa.PublicKey.load_pkcs1(pub) # use the public key to encrypt the content, which must be binary info_encrypted = rsa.encrypt(info.encode('utf-8'), public_key) return info_encrypted def decry(self, info_encrypted): """ decrypt information :param info_encrypted: encrypted information :return: info """ # read the private key from the file with open(self.private_key_path, 'rb') as f: pri = f.read() # convert pri to original state private_key = rsa.PrivateKey.load_pkcs1(pri) # decrypt with private key to obtain the decrypted content msg = rsa.decrypt(info_encrypted, private_key) info = msg.decode('utf-8') # decode return info rsa_obj = Rsa(1024) # 实例化 rsa_obj.key_transform_store() # info_encrypted = rsa_obj.encry('我是真心喜欢你的。') # 加密 print(info_encrypted) info = rsa_obj.decry(info_encrypted) # 解密 print(info) # 我是真心喜欢你的。
这里会出现一个问题:由于RSA的特性,一个1024位的密钥只能加密117位字节数据,当数据量超过117位字节的时候,程序就会抛出异常。如下测试会抛出:OverflowError: 189 bytes needed for message, but there is only space for 117
rsa_obj = Rsa(1024) # 实例化 rsa_obj.key_transform_store() # info_encrypted = rsa_obj.encry('我是真心喜欢你的。我是真心喜欢你的。我是真心喜欢你的。我是真心喜欢你的。我是真心喜欢你的。我是真心喜欢你的。我是真心喜欢你的。') # 加密 print(info_encrypted) info = rsa_obj.decry(info_encrypted) # 解密 print(info)
。。。。。。
后记: 通常使用中, 会先对数据进行bas64加密, 再对加密后的内容使用rsa加密, 最后对rsa解密后的内容进行bas64解密。
以上。