java - Pycrypto RSA PKCS1 OAEP SHA256 与 Java 的互操作性

Question

我在 Python + Pycryptodome(Pycrypto 分支)中使用以下代码使用 RSA PKCS#1 OAEP SHA256(RSA/ECB/OAEPWithSHA-256AndMGF1Padding)加密消息:

from Crypto.Cipher import PKCS1_OAEP
from Cryptodome.Hash import SHA256
cipher = PKCS1_OAEP.new(key=self.key, hashAlgo=SHA256))
ciphertext = cipher.encrypt(cek)

和下面的 Java 代码来解密它:

Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
cipher.init(Cipher.DECRYPT_MODE, privateKey);

byte[] cek = cipher.doFinal(ciphertext);

但是，我得到:

Exception in thread "main" javax.crypto.BadPaddingException: Decryption error
    at sun.security.rsa.RSAPadding.unpadOAEP(RSAPadding.java:499)
    at sun.security.rsa.RSAPadding.unpad(RSAPadding.java:293)
    at com.sun.crypto.provider.RSACipher.doFinal(RSACipher.java:363)
    at com.sun.crypto.provider.RSACipher.engineDoFinal(RSACipher.java:389)
    at javax.crypto.Cipher.doFinal(Cipher.java:2165)

Answer 1

在 Sun JCE 中，RSA/ECB/OAEPWithSHA-256AndMGF1Padding 实际上意味着:

• 哈希 = SHA256
• MGF1 = SHA1

另一方面，Pycrypto(包括 Pycryptodome)在使用 PKCS1_OAEP.new(hashAlgo=SHA256) 时假设如下:

• 哈希 = SHA256
• MGF1 = SHA256

为了使 Pycrypto 与 Sun JCE 兼容，您需要通过传递 mgfunc 参数来配置 Pycrypto 的 OAEP MGF1 函数以使用 SHA1:

from Cryptodome.Cipher import PKCS1_OAEP
from Cryptodome.Hash import SHA256, SHA1
from Cryptodome.Signature import pss

cipher = PKCS1_OAEP.new(key=self.key, hashAlgo=SHA256, mgfunc=lambda x,y: pss.MGF1(x,y, SHA1))
ciphertext = cipher.encrypt(cek)

值得注意的是，根据breaking down RSA/ECB/OAEPWITHSHA-256ANDMGF1PADDING , BouncyCaSTLe 以与 Pycrypto 相同的方式对 Hash 和 MGF1 使用 SHA256。