将RSA解密功能从Golang转换为Python

Question

I need an equivalent of this golang function in Python :

func RsaDecrypt(ciphertext []byte) ([]byte, error) {
    block, _ := pem.Decode(privateKey)
    if block == nil {
        return nil, errors.New("private key error!")
    }
    priv, err := x509.ParsePKCS1PrivateKey(block.Bytes)
    if err != nil {
        return nil, err
    }
    return rsa.DecryptPKCS1v15(rand.Reader, priv, ciphertext)
}

I'm a python developer, and do not understand how this works. I have created this function, but it is not the same:

import rsa

with open("rsa.key") as f:
    priv_key_pkcs1 = f.read()

priv_key = rsa.PrivateKey.load_pkcs1(priv_key_pkcs1)
line = '''
Lyzkh2pqrisgM_p32O6FmA8oDvzaimvrU9zyd0vyW6HBM2BznuHLbAYUMGp5oYgEHCxmZTWDs67Jt5AGulfn-LrcewCQi89wrb00ZvP69YdjwBe-7aoXBG4_zNMZ7ecLgd8WzUqBGGtVvUhCTVSBBi85mNMSCcgYHt__PFefRHZE09nHnEX25w6iR0ZZlQxuESBkuqTcs8qjUhs2Guin1xBMSWRINj4JDdCjIVHV4hdSjrINgFU-VF1sYFRibWcboYlXifROOxCF50MGtIBkcf7dnqsrR8HEXgZLnCyikhhlQAFoh2hsj4lPWNpWum-dBWj-B0b8P-hRmermDzcPqA==
'''
encrypted = line.decode('base64')
decrypted = rsa.decrypt(encrypted, priv_key)
print decrypted

Can anybody can help me to convert golang function in Python? Or give me some info where I was wrong in my actual python code?

Answer 1

You're using the wrong base64 decoder to decode your ciphertext. It's evident from the "-" and "_" characters present in your ciphertext that it was encoded using the URL-safe variant of base64. To decode this you should use the base64 module, e.g.

import base64

line = '''
Lyzkh2pqrisgM_p32O6FmA8oDvzaimvrU9zyd0vyW6HBM2BznuHLbAYUMGp5oYgEHCxmZTWDs67Jt5AGulfn-LrcewCQi89wrb00ZvP69YdjwBe-7aoXBG4_zNMZ7ecLgd8WzUqBGGtVvUhCTVSBBi85mNMSCcgYHt__PFefRHZE09nHnEX25w6iR0ZZlQxuESBkuqTcs8qjUhs2Guin1xBMSWRINj4JDdCjIVHV4hdSjrINgFU-VF1sYFRibWcboYlXifROOxCF50MGtIBkcf7dnqsrR8HEXgZLnCyikhhlQAFoh2hsj4lPWNpWum-dBWj-B0b8P-hRmermDzcPqA==
'''

encrypted = base64.urlsafe_b64decode(line)
print len(encrypted)
print encrypted.encode('hex')