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，这将相当于使用PyCryptodome。但是，结果值的长度仅为16，表示可能存在解密错误

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RSA。有人知道我如何用PyCryptodome或其他维护的库解密此值吗

Answer 1

PyCryptodome没有提供一种内置的方法来解密教科书中的RSA，但是可以使用标准库中的模幂运算来解密

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))