使用Java解密3Des中的值

Question

我無法解密使用3Des的第三方的值。他們給了我一個密鑰，一個加密的值，使用的模式，以及解密的值應該是什麼，但到目前爲止，我一直無法弄清楚如何從a點到b點。我相信問題與他們給予我的關鍵有關 - 他們說這是明文密鑰，但我認爲它仍然需要進一步改變。

下面的代碼是是我的初始試圖瞭解如何解密（在這種情況下AC9C5A46A63FC9EA）的值

任何見解，將不勝感激的一個例子。

import java.security.spec.KeySpec; 
import javax.crypto.Cipher; 
import javax.crypto.SecretKey; 
import javax.crypto.SecretKeyFactory; 
import javax.crypto.spec.DESedeKeySpec; 

public class TripleDes2 { 

private static final String UNICODE_FORMAT = "UTF8"; 
private static final String DESEDE_ENCRYPTION_SCHEME = "DESede"; 
private static final String CIPHER_ALG = "DESede/ECB/Nopadding"; //assuming no padding 
private KeySpec ks; 
private SecretKeyFactory skf; 
private Cipher cipher; 
private byte[] arrayBytes; 
private String myEncryptionKey; 
private SecretKey key; 

public static void main(String args []) throws Exception { 
    TripleDes2 td= new TripleDes2(); 

    String decrypted = td.decrypt("AC9C5A46A63FC9EA"); 
    System.out.println("expecting: 04286EDDFDEA6BD7"); 
    System.out.println("found: " + decrypted); 
} 

public TripleDes2() throws Exception { 
    myEncryptionKey = "1032FD2CD64A9D7FA4D061F76B04BFEA"; 
    arrayBytes = myEncryptionKey.getBytes(UNICODE_FORMAT); 
    ks = new DESedeKeySpec(arrayBytes); 
    skf = SecretKeyFactory.getInstance(DESEDE_ENCRYPTION_SCHEME); 

    cipher = Cipher.getInstance(CIPHER_ALG); 
    key = skf.generateSecret(ks); 
} 

public String decrypt(String encryptedString) { 
    String decryptedText=null; 
    try { 
     cipher.init(Cipher.DECRYPT_MODE, key); 
     byte[] encryptedText = encryptedString.getBytes(); 
     byte[] plainText = cipher.doFinal(encryptedText); 
     decryptedText= new String(plainText); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 
    return decryptedText; 
} 
} 

Answer 1

你快把它要複雜得多，你需要與SecretKeyFactory等，但主要問題在於你不能正確轉換十六進制數字。

class TripleDES 
{ 

    private final String key; 

    public static void main(String... args) 
    throws Exception 
    { 
    TripleDES td = new TripleDES("1032FD2CD64A9D7FA4D061F76B04BFEA"); 
    String decrypted = td.decrypt("AC9C5A46A63FC9EA"); 
    System.out.println("expecting: 04286EDDFDEA6BD7"); 
    System.out.println("found: " + decrypted); 
    } 

    TripleDES(String key) 
    { 
    this.key = key; 
    } 

    public String decrypt(String input) 
    throws Exception 
    { 
    byte[] tmp = h2b(this.key); 
    byte[] key = new byte[24]; 
    System.arraycopy(tmp, 0, key, 0, 16); 
    System.arraycopy(tmp, 0, key, 16, 8); 
    Cipher cipher = Cipher.getInstance("DESede/ECB/NoPadding"); 
    cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "DESede")); 
    byte[] plaintext = cipher.doFinal(h2b(input)); 
    return b2h(plaintext); 
    } 

    private static byte[] h2b(String hex) 
    { 
    if ((hex.length() & 0x01) == 0x01) 
     throw new IllegalArgumentException(); 
    byte[] bytes = new byte[hex.length()/2]; 
    for (int idx = 0; idx < bytes.length; ++idx) { 
     int hi = Character.digit((int) hex.charAt(idx * 2), 16); 
     int lo = Character.digit((int) hex.charAt(idx * 2 + 1), 16); 
     if ((hi < 0) || (lo < 0)) 
     throw new IllegalArgumentException(); 
     bytes[idx] = (byte) ((hi << 4) | lo); 
    } 
    return bytes; 
    } 

    private static String b2h(byte[] bytes) 
    { 
    char[] hex = new char[bytes.length * 2]; 
    for (int idx = 0; idx < bytes.length; ++idx) { 
     int hi = (bytes[idx] & 0xF0) >>> 4; 
     int lo = (bytes[idx] & 0x0F); 
     hex[idx * 2] = (char) (hi < 10 ? '0' + hi : 'A' - 10 + hi); 
     hex[idx * 2 + 1] = (char) (lo < 10 ? '0' + lo : 'A' - 10 + lo); 
    } 
    return new String(hex); 
    } 

} 

Answer 2

主要問題似乎是使用包含通過getBytes（）轉換爲字節數組的十六進制數據的字符串。

對於一個十六進制字符串轉換成您需要的外部庫的字節數組表示，如apache.commons.codec.binary：

myEncryptionKey = "1032FD2CD64A9D7FA4D061F76B04BFEA"; 
arrayBytes = Hex.decodeHex(myEncryptionKey.toCharArray());