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我正在尝试使用 RSA 算法加密和解密字符串。这里加密工作良好，但问题在于解密。代码在 DECRYPT 方法中到达 doFinal 时终止。我输入错误还是公钥和私钥有问题？请给我有关此的建议。感谢你。

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] -> [B@4a96a

4

2 回答 2

9

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

尝试将加密的 byte[] 直接送回解密函数，并用于new String(dec)打印结果。如果要将加密数据查看/保存为字符串，请将其编码为十六进制或 base64。

这是区别。byte[]表示字节数组。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，则一系列bytes 和 a之间的区别String可能看起来微不足道，但是有很多方法可以用二进制表示字符串。您所做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；它只是在看位。

如果要加密字符串，则需要将其转换为一系列字节。在另一端，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()并且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 utf-8 而 Bob 使用 utf-16，那么她的信息对他来说就没有多大意义。因此，最好使用例如myString.getBytes("utf-8")和来指定字符编码new String(myBytea,"utf-8")。

以下是我正在处理的项目中的一些功能，以及演示main功能：

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"));
    }
}
于 2012-04-19T05:32:15.837 回答
-3

'[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。

于 2016-09-11T20:32:41.663 回答