python 实现私钥加密公钥解密

摘要：实现私钥加密公钥解密业界普遍的用法是公钥用来加密，私钥来解密，许多人却不知道也可以用私钥加密，公钥来解密基础知识对称加密非对称加密公私钥的几个常见格式图片来源使用私钥加密待编辑使用公钥解密参考文档的实现公钥格式如下，若公钥已经是格式，则无需

业界普遍的用法是公钥用来加密，私钥来解密，许多人却不知道也可以用私钥加密，公钥来解密

图片来源： https://www.openssl.org/docs/...

待编辑

参考文档：

https://www.cnblogs.com/masak...
https://www.linuxidc.com/Linu...

from rsa import PublicKey, common, transform, core

# 公钥格式如下，若公钥已经是 RSAPublicKey 格式，则无需将 pub key 转换为 string
PUB_KEY_STRING = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCsKfRext58G0buLDabQQNBVWEB1/B62PapiZ2tSiITw/3X4cI00QB6m7dryMqs7pKntUD3MTGeMCj9zwXX0kmqkrA8og0H0eOHQnAeuw671lkSVYnD1YVcICPv+fbJ1JL+DP3RkXuy0+V2iQC2GDQmfgTcKVowU4c+ToQIp0pUBQIDAQAB"

class DecryptByPublicKey(object):
    """
    使用 publib key来解密用primary key加密后生成的base64类型的密文
    返回解密后的数据
    """
    def __init__(self, encrypt_text):
        self.encrypt_text = encrypt_text

    @staticmethod
    def str2key(s):
        # 对字符串解码, 解码成功返回 模数和指数
        b_str = base64.b64decode(s)
        if len(b_str) < 162:
            return False
        hex_str = ""
        # 按位转换成16进制
        for x in b_str:
            h = hex(ord(x))[2:]
            h = h.rjust(2, "0")
            hex_str += h
        # 找到模数和指数的开头结束位置
        m_start = 29 * 2
        e_start = 159 * 2
        m_len = 128 * 2
        e_len = 3 * 2
        modulus = hex_str[m_start:m_start + m_len]
        exponent = hex_str[e_start:e_start + e_len]
        return modulus,exponent

    @staticmethod
    def f(cipher, PUBLIC_KEY):
        """
        decrypt msg by public key
        """
        public_key = PublicKey.load_pkcs1(PUBLIC_KEY)
        encrypted = transform.bytes2int(cipher)
        decrypted = core.decrypt_int(encrypted, public_key.e, public_key.n)
        text = transform.int2bytes(decrypted)
        if len(text) > 0 and text[0] == "x01":
            pos = text.find("x00")
            if pos > 0:
                return text[pos+1:]
            else:
                return None

    def pub_decrypt_with_pubkeystr(self):
        """
        将 base64 编码的 pub_key 转成 bio 对象,
        再将bio对象转换成公钥对象
        """
        # 将 pub key 转换为 string
        # Note: 若公钥已经是 RSAPublicKey 格式，则无需执行这一步 ！
        try:
            key = self.str2key(PUB_KEY_STRING) # 将 base64 编码的公钥进行拆解，取出模数和指数
            if not key:
                raise Exception, "decode public key falid"
            modulus = int(key[0], 16)
            exponent = int(key[1], 16)
            rsa_pubkey = PublicKey(modulus, exponent) # 根据模数和指数生成 pubkey 对象
            self.pub_key = rsa_pubkey.save_pkcs1()    # 将 pubkey 对象导出为 RSAPublicKey 格式的公钥
        except Exception, e:
            assert False, "Invalid public_key"

    
        # 开始解密
        try:
            ret = self.f(self.encrypt_text.decode("base64"), self.pub_key)
        except Exception, e:
            self.error_info = str(e)
            assert False, "Decrypt by public key fails! Invalid encrypt_text"
        return ret

if __name__ == "__main__":
    encrypt_text = "xxxxxx"  # encrypt_text 是被私钥加密后的密文
    decrypt = DecryptByPublicKey(encrypt_text)
    result = decrypt.pub_decrypt_with_pubkeystr()
    print result

# 系统库
import six
import logging
import coloredlogs
# 第三方库
import rsa
import base64

p = logging.getLogger()
console_formatter = logging.StreamHandler()
console_formatter.setFormatter(coloredlogs.ColoredFormatter("%(asctime)s - %(module)-14s[line:%(lineno)3d] - %(levelname)-8s: %(message)s"))
p.addHandler(console_formatter)
p.setLevel(logging.DEBUG)

PUB_KEY_STRING = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCsKfRext58G0buLDabQQNBVWEB1/B62PapiZ2tSiITw/3X4cI00QB6m7dryMqs7pKntUD3MTGeMCj9zwXX0kmqkrA8og0H0eOHQnAeuw671lkSVYnD1YVcICPv+fbJ1JL+DP3RkXuy0+V2iQC2GDQmfgTcKVowU4c+ToQIp0pUBQIDAQAB"


class DecryptByPublicKey(object):
    """
        先产生模数因子
        然后生成rsa公钥
        再使用rsa公钥去解密传入的加密str
    """
    def __init__(self, encrypt_text):
        self._encrypt_text = encrypt_text
        self._pub_string_key = PUB_KEY_STRING
        # 使用公钥字符串求出模数和因子
        self._modulus = None   # 模数
        self._exponent = None  # 因子
        # 使用PublicKey(模数,因子)算出公钥
        self._pub_rsa_key = None

    def _gen_modulus_exponent(self, s) ->int:
        p.debug("Now base64 decode pub key,return modulus and exponent")
        # 对字符串解码, 解码成功返回 模数和指数
        b_str = base64.b64decode(s)
        if len(b_str) < 162:
            return False
        hex_str = b_str.hex()
        # 找到模数和指数的开头结束位置
        m_start = 29 * 2
        e_start = 159 * 2
        m_len = 128 * 2
        e_len = 3 * 2
        self._modulus = int(hex_str[m_start:m_start + m_len], 16)
        self._exponent = int(hex_str[e_start:e_start + e_len], 16)

    def _gen_rsa_pubkey(self):
        # 将pub key string 转换为 pub rsa key
        p.debug("Now turn key string to rsa key")
        try:
            rsa_pubkey = rsa.PublicKey(self._modulus, self._exponent)
            # 赋值到_pub_rsa_key
            self._pub_rsa_key = rsa_pubkey.save_pkcs1()
            # p.debug("self._pub_rsa_key：{}".format(self._pub_rsa_key))
        except Exception as e:
            p.error(e)
            p.error("Invalid public_key")
            raise e

    def decode(self) ->str:
        """
        decrypt msg by public key
        """
        p.debug("Now decrypt msg by public rsa key")
        b64decoded_encrypt_text = base64.b64decode(self._encrypt_text)
        public_key = rsa.PublicKey.load_pkcs1(self._pub_rsa_key)
        encrypted = rsa.transform.bytes2int(b64decoded_encrypt_text)
        decrypted = rsa.core.decrypt_int(encrypted, public_key.e, public_key.n)
        # p.debug("decrypted: {}".format(decrypted))
        decrypted_bytes = rsa.transform.int2bytes(decrypted)
        # 这里使用了six库的iterbytes()方法去模拟python2对bytes的轮询
        if len(decrypted_bytes) > 0 and list(six.iterbytes(decrypted_bytes))[0] == 1:
            try:
                raw_info = decrypted_bytes[decrypted_bytes.find(b"x00")+1:]
            except Exception as e:
                p.error(e)
                raise e
        return raw_info.decode("utf-8")

    def decrypt(self) -> str:
        """
        先产生模数因子
        然后生成rsa公钥
        再使用rsa公钥去解密
        """
        self._gen_modulus_exponent(self._pub_string_key)
        self._gen_rsa_pubkey()
        ret = self.decode()
        return ret


if __name__ == "__main__":
    encrypt_text = "xxxxxx"  # encrypt_text 是被私钥加密后的密文
    result = DecryptByPublicKey(encrypt_text).decrypt()
    p.info(result)