将RSA解密从PyCrypto迁移到PyCryptodome

Question

使用PyCrypto库，以下代码打印127:

from Crypto.PublicKey import RSA
import base64
# Private key in tuple form (obscured for privacy)
key = [1, 1, 1]
bk = "zJuG60z9Iv..." # (obscured for privacy)
privatekey = RSA.construct(key)
result = privatekey.decrypt(base64.b64decode(bk))
print(len(result))

据我所知，这相当于使用PyCryptodome。然而，得到的值只有16的长度，这表明可能存在解密错误。

from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_v1_5
import base64
# Private key in tuple form (obscured for privacy)
key = [1, 1, 1]
bk = "zJuG60z9Iv..." # (obscured for privacy)
privatekey = RSA.construct(key)
cipher = PKCS1_v1_5.new(privatekey)
result = cipher.decrypt(base64.b64decode(bk), None)
print(len(result))

我相信这是因为我的密文使用了教科书上的未添加RSA。有人知道我如何用PyCryptodome或其他维护的库解密这个值吗？

Answer 1

PyCryptodome没有提供一个内置的方法来解密教科书RSA，但可以使用标准库中的模幂来解密。

from Crypto.PublicKey import RSA
import base64
# Private key in tuple form (obscured for privacy)
key = [1, 1, 1]
bk = "zJuG60z9Iv..." # (obscured for privacy)
privatekey = RSA.construct(key)
ciphertext = base64.b64decode(bk)
ct_int = int.from_bytes(ciphertext, 'big')
pt_int = pow(ct_int, privatekey.d, privatekey.n)
plaintext = pt_int.to_bytes(privatekey.size_in_bytes(), 'big').lstrip(b'x00')
print(len(plaintext))