Question

我正在尝试使用RSA算法加密和解密字符串。这里的加密工作正常，但问题在于解密。代码在DECRYPT方法中到达doFinal时终止。我输错了还是公钥和私钥有问题？请给我这个建议。谢谢你。

public class rsa 
{   
 private KeyPair keypair;       

 public rsa() throws NoSuchAlgorithmException, NoSuchProviderException 
    {
        KeyPairGenerator keygenerator = KeyPairGenerator.getInstance("RSA");
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG", "SUN");
        keygenerator.initialize(1024, random);
        keypair = keygenerator.generateKeyPair();
    }
public String ENCRYPT(String Algorithm, String Data ) throws Exception
{   
    String alg = Algorithm;
    String data=Data;
    byte[] encrypted=new byte[2048];
    if(alg.equals("RSA"))
    {   

        PublicKey publicKey = keypair.getPublic();
        Cipher cipher;
        cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
         encrypted = cipher.doFinal(data.getBytes());
        System.out.println("Encrypted String[RSA] -> " + encrypted);
    }
    return encrypted.toString();
}
public String DECRYPT(String Algorithm, String Data ) throws Exception
{   
    String alg = Algorithm;
    byte[] Decrypted=Data.getBytes();


    if(alg.equals("RSA"))
    {   

        PrivateKey privateKey = keypair.getPrivate();
        Cipher cipher;  
        cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] dec = cipher.doFinal(Decrypted);

        System.out.println("Decrypted String[RSA] -> " + dec.toString());

    }
    return Decrypted.toString();
}
public static void main(String[] args) throws Exception
{
    rsa RSA=new rsa();
    RSA.ENCRYPT("RSA", "avinash");
    RSA.DECRYPT("RSA","[B@cb7e2c");
}

}

 got exception as

Exception in thread "main" javax.crypto.BadPaddingException: Data must start with zero
at sun.security.rsa.RSAPadding.unpadV15(Unknown Source)
at sun.security.rsa.RSAPadding.unpad(Unknown Source)
at com.sun.crypto.provider.RSACipher.doFinal(RSACipher.java:356)
at com.sun.crypto.provider.RSACipher.engineDoFinal(RSACipher.java:382)
at javax.crypto.Cipher.doFinal(Cipher.java:2086)
at EncryptionProvider.rsa.DECRYPT(rsa.java:56)
at EncryptionProvider.rsa.main(rsa.java:68)

加密字符串[RSA] - ＆gt; [B @ 4a96a

Answer 1

[B@cb7e2c不是加密的输出。这是尝试在byte []对象上打印或调用toString()的结果。（例如，查看System.out.println(new byte[0]);）

的结果

尝试将加密的byte []直接反馈到解密函数中，然后使用new String(dec)打印结果。如果要将加密数据作为字符串查看/保存，请将其编码为十六进制或base64。

这是区别。 byte[]表示一个字节数组。它是二进制数据，一系列8位有符号数。如果您习惯于仅使用ascii，那么一系列byte和String之间的区别可能看起来微不足道，但有很多方法可以用二进制表示字符串。您正在进行的加密和解密并不关心字符串的外观或数据是否代表字符串;它只是看着这些位。

如果要加密字符串，则需要将其转换为一系列字节。另一方面，一旦你解密了构成字符串的字节，你就需要将它们转换回来。 myString.getBytes()和new String(myBytea)通常很有效，但有点草率，因为它们只使用默认编码。如果Alice的系统使用了utf-8而Bob使用了utf-16，那么她的信息对他来说就没有多大意义了。因此，最好使用myString.getBytes("utf-8")和new String(myBytea,"utf-8")来指定字符编码。

以下是我正在处理的项目中的一些函数，以及演示main函数：

import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.xml.bind.DatatypeConverter;

public class RSAExample {
    private static byte[] h2b(String hex){
        return DatatypeConverter.parseHexBinary(hex);
    }
    private static String b2h(byte[] bytes){
        return DatatypeConverter.printHexBinary(bytes);
    }

    private static SecureRandom sr = new SecureRandom();

    public static KeyPair newKeyPair(int rsabits) throws NoSuchAlgorithmException {
        KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
        generator.initialize(rsabits, sr);
        return generator.generateKeyPair();
    }

    public static byte[] pubKeyToBytes(PublicKey key){
        return key.getEncoded(); // X509 for a public key
    }
    public static byte[] privKeyToBytes(PrivateKey key){
        return key.getEncoded(); // PKCS8 for a private key
    }

    public static PublicKey bytesToPubKey(byte[] bytes) throws InvalidKeySpecException, NoSuchAlgorithmException{
        return KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(bytes));
    }
    public static PrivateKey bytesToPrivKey(byte[] bytes) throws InvalidKeySpecException, NoSuchAlgorithmException{
        return KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(bytes));
    }

    public static byte[] encryptWithPubKey(byte[] input, PublicKey key) throws IllegalBlockSizeException, BadPaddingException, InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(input);
    }
    public static byte[] decryptWithPrivKey(byte[] input, PrivateKey key) throws IllegalBlockSizeException, BadPaddingException, InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(input);
    }


    public static void main(String[] args) throws Exception {
        KeyPair kp = newKeyPair(1<<11); // 2048 bit RSA; might take a second to generate keys
        PublicKey pubKey = kp.getPublic();
        PrivateKey privKey = kp.getPrivate();
        String plainText = "Dear Bob,\nWish you were here.\n\t--Alice";
        byte[] cipherText = encryptWithPubKey(plainText.getBytes("UTF-8"),pubKey);
        System.out.println("cipherText: "+b2h(cipherText));
        System.out.println("plainText:");
        System.out.println(new String(decryptWithPrivKey(cipherText,privKey),"UTF-8"));
    }
}

Answer 2

'[B @ 4a96a'不是加密字符串。这是字符串的数据。真正的加密发生在这里

//add this line to your code, it will work fine.
"String encryptedValue = new BASE64Encoder().encode(encrypted);"

现在打印encryptedValue以查看加密结果。

在RSA加密中需要帮助（doFinal）

2 个答案: