Python 和 Java 之间的 RSA 加密填充问题

Question

我正在尝试使用 android 中客户端生成的 public 密钥对 python 中的某些数据进行 RSA 加密。加密成功（至少没有例外）。但是，当尝试使用 android 中的私钥解密数据时，它会抛出错误填充异常。

相关进口：

import javax.crypto.Cipher;
import javax.crypto.spec.OAEPParameterSpec;
import javax.crypto.spec.PSource;
import java.security.spec.MGF1ParameterSpec;
import java.util.*;
import android.util.Base64;

解密：

private static String RSA_CONFIGURATION = "RSA/ECB/OAEPWithSHA-256AndMGF1Padding";
private static String RSA_PROVIDER = "BC";

public static decrypt(Key key, String encryptedString){
    Cipher c = Cipher.getInstance(RSA_CONFIGURATION, RSA_PROVIDER);
    c.init(Cipher.DECRYPT_MODE, key, new OAEPParameterSpec("SHA-256", "MGF1", MGF1ParameterSpec.SHA1,
                    PSource.PSpecified.DEFAULT));
    byte[] decodedBytes = c.doFinal(Base64.decode(base64cypherText.getBytes("UTF-8"), Base64.DEFAULT));
    clearText = new String(decodedBytes, "UTF-8");
}

异常：

javax.crypto.BadPaddingException: data hash wrong
    at com.android.org.bouncycastle.jcajce.provider.asymmetric.rsa.CipherSpi.engineDoFinal(CipherSpi.java:478)
    at javax.crypto.Cipher.doFinal(Cipher.java:1204)
    at org.ambientdynamix.security.CryptoUtils.decryptRsa(CryptoUtils.java:204)

测试键：

Answer 1

OAEP 填充有两个参数：

消息摘要算法
掩码生成函数

我在 Java 中看到您将 SHA-256 和 MGF1 与 SHA-1 哈希一起使用。它们必须与 Python.

使用的参数不匹配

Python和Java的区别在于Python代码对消息摘要和掩码摘要使用相同的摘要。而 Java（Sun 提供者和 BouncyCastle 提供者）默认使用 SHA-1 进行掩码消化。因此需要明确指定所有参数：

byte[] cipherTextBytes = DatatypeConverter.parseBase64Binary(cipherText);
byte[] privateKeyBytes = DatatypeConverter.parseBase64Binary(privateKeyStr);

KeyFactory kf = KeyFactory.getInstance("RSA");
PKCS8EncodedKeySpec ks = new PKCS8EncodedKeySpec(privateKeyBytes);
PrivateKey privateKey = kf.generatePrivate(ks);

Cipher c = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
c.init(Cipher.DECRYPT_MODE, privateKey, new OAEPParameterSpec("SHA-256",
        "MGF1", MGF1ParameterSpec.SHA256, PSource.PSpecified.DEFAULT));
byte[] plainTextBytes = c.doFinal(cipherTextBytes);
String plainText = new String(plainTextBytes);

System.out.println(plainText);

Answer 2

解决这个问题的另一种方法：

默认mgfunc与hashAlgo一致

所以，我们可以这样更改 mgfunc：

cipher = PKCS1_OAEP.new(pubkey, hashAlgo=SHA256,mgfunc=lambda x,y:MGF1(x,y,SHA1))

Answer 3

为了解决这个问题，我不得不在私钥字符串的每一行末尾添加换行符

  private RSAPrivateKey getPrivateKey(String filename) throws Exception {
    String privateKeyPEM        =   getKey(filename);
    privateKeyPEM               =   privateKeyPEM.replace("-----BEGIN PRIVATE KEY-----\n", "");
    privateKeyPEM               =   privateKeyPEM.replace("-----END PRIVATE KEY-----", "");
    byte[] encoded              =   Base64.decodeBase64(privateKeyPEM);
    KeyFactory kf               =   KeyFactory.getInstance("RSA");
    PKCS8EncodedKeySpec keySpec =   new PKCS8EncodedKeySpec(encoded);
    RSAPrivateKey privKey       =   (RSAPrivateKey) kf.generatePrivate(keySpec);
    return privKey;
}


private String getKey (String filename) throws IOException {
    String responseContent  =   null;
    try (InputStream stream =   this.getClass().getResourceAsStream("/" + filename); 
        InputStreamReader streamReader = new InputStreamReader(stream, "UTF-8"); 
        BufferedReader br = new BufferedReader(streamReader)) {
        StringBuilder builder = new StringBuilder ();
        String line;
        while ((line = br.readLine()) != null) {
            builder.append (line + "\n");
        }
        responseContent = builder.toString();
    }
    catch (IOException expGeneral) {
        logger.error("Cannot load Crypto related file [" + filename + "].", expGeneral);
        throw expGeneral;
    }
    return responseContent;
}

以上是解决方法

Python 和 Java 之间的 RSA 加密填充问题

RSA Encryption Padding issues between Python and Java

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