不加密&正确解密

Question

我编写的用于加密和解密的以下 AES 类有些奇怪。当我复制 AES 对象并选择加密纯文本，然后我立即尝试解密刚刚加密的文本时，它不会完全解密（并且每次的解密方式都不同）。

例如，我使用一个简单的 JSP 来初始化它，如下所示：

<%@page import="com.myclass.util.AES"%>
<%
        String hexMessage = "0xe800a86d90d2074fbf339aa70b6d0f62f047db15ef04c86b488a1dda3c6c4f2f2bbb444a8c709bbb4c29c7ff1f1e"; 
        String keyText = "12345678abcdefgh";//*/

        AES e = new AES();
        //e.setKey(keyText);
        String plaintext = "This should decode & encode!";
        String ciphertext = e.encrypt(plaintext);
        out.println(ciphertext);
        out.println("<BR>");
        out.println(e.decrypt(ciphertext));    
%>

输出随每个页面加载而变化： 一次：

0x663D64E6A0AE455AB3D25D5AF2F77C72202627EBA068E6DEBE5F22C31
This should decoÁdìmèåV4ÉkÓ 

另一次：

0x5F5CF31961505F01EA9D5B7D7BFC656BD3117725D2EA041183F48
This s2??XêêÈ&ÀܧF?ÒDÒ­?

等等：

0xC7178A34C59F74E5D68F7CE5ED655B670A0B4E715101B4DDC2122460E8
Tà@¼R×ËÖ?_U?xÎÚ?Ba?b4r!©F 

我创建的类如下：

package com.myclass.util;

import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Security;
import java.util.regex.Pattern;
import javax.crypto.*;
import javax.crypto.spec.*;    

   public class AES {
       private static String provider = "AES/CTR/NoPadding";
       private static String providerkey = "AES";
       private static int size = 128;
       private SecretKeySpec key;
       private Cipher cipher;
       private byte[] ivBytes = new byte[size/8];
       private IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);


       public AES() throws NoSuchAlgorithmException, NoSuchPaddingException, NoSuchProviderException{
           Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
           KeyGenerator kgen = KeyGenerator.getInstance(providerkey);
           kgen.init(size); // 192 and 256 bits may not be available
           SecretKey skey = kgen.generateKey();
           byte[] raw = skey.getEncoded();
           key = new SecretKeySpec(raw, providerkey);
           cipher = Cipher.getInstance(provider);
           for(int x = 0; x < (size/8); x++)
               ivBytes[x] = 00;
           ivSpec = new IvParameterSpec(ivBytes);
       }

       public void setKey(String keyText){
           byte[] bText = new byte[size/8];
           bText = keyText.getBytes();
           key = new SecretKeySpec(bText, providerkey);
       }

       public void setIV(String ivText){
           setIV(ivText.getBytes());
       }

       public void setIV(byte[] ivByte){
           byte[] bText = new byte[size/8];
           bText = ivByte;
           ivBytes = bText;
           ivSpec = new IvParameterSpec(ivBytes);
       }

       public String encrypt(String message) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException, InvalidAlgorithmParameterException{
           cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);
           byte[] encrypted = cipher.doFinal(message.getBytes());
           return byteArrayToHexString(encrypted);
       }
       public String decrypt(String hexCiphertext) throws IllegalBlockSizeException, BadPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, UnsupportedEncodingException{
           cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);
           byte[] dec = hexStringToByteArray(hexCiphertext);
           byte[] decrypted = cipher.doFinal(dec);
           return new String(decrypted);
       }

       private static String byteArrayToHexString( byte [] raw ) {
            String hex = "0x";
            String s = new String(raw);
            for(int x = 0; x < s.length(); x++){
                char[] t = s.substring(x, x + 1).toCharArray();
                hex += Integer.toHexString((int) t[0]).toUpperCase();
            }
            return hex;
       }

       private static byte[] hexStringToByteArray(String hex) {
            Pattern replace = Pattern.compile("^0x");
            String s = replace.matcher(hex).replaceAll("");

            byte[] b = new byte[s.length() / 2];
            for (int i = 0; i < b.length; i++){
              int index = i * 2;
              int v = Integer.parseInt(s.substring(index, index + 2), 16);
              b[i] = (byte)v;
            }
            return b;
       }


   }

基于不同的结果，我想知道 IV 是否以某种方式搞砸了，但我真的不明白为什么......

[编辑] 看起来就像它不是 IV，如果我硬编码解密仍然会有所不同。如果我对密钥进行硬编码，它会停止变化，但仍然无法正确解密文本:-(。

--------------------- ====== =============== ---------------------

添加我在下面创建的最终解决方案，基于 owlstead 的代码和建议它执行以下操作：
1) 初始化时有随机密钥和 iv。
2) 允许您将 key 或 iv 指定为常规字符串或十六进制编码字符串。
3) 自动截断或空填充任何给定的 key 或 iv 以使其达到适当的长度。

注意：第 3 项可能被视为极其不安全，因为它允许您做一些愚蠢的事情。出于我的目的，我需要它，但请谨慎使用。如果您为密钥填充一个短字符串，您的内容将不会非常安全。

--------------------- ===== =============== ---------------------

package com.myclass.util;

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.spec.InvalidParameterSpecException;
import java.util.regex.Pattern;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

   public class AES {
       private static Charset PLAIN_TEXT_ENCODING = Charset.forName("UTF-8");
       private static String CIPHER_TRANSFORMATION = "AES/CTR/NoPadding";
       private static String KEY_TYPE = "AES";
       private static int KEY_SIZE_BITS = 128;

       private SecretKey key;
       private Cipher cipher = Cipher.getInstance(CIPHER_TRANSFORMATION);
       private byte[] ivBytes = new byte[KEY_SIZE_BITS/8];

   public AES() throws NoSuchAlgorithmException, NoSuchPaddingException, NoSuchProviderException, InvalidParameterSpecException, InvalidKeyException, InvalidAlgorithmParameterException{
       KeyGenerator kgen = KeyGenerator.getInstance(KEY_TYPE);
       kgen.init(KEY_SIZE_BITS); 
       key = kgen.generateKey();
       cipher.init(Cipher.ENCRYPT_MODE, key);
       ivBytes = cipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
   }

   public String getIVAsHex(){
       return byteArrayToHexString(ivBytes);
   }

   public String getKeyAsHex(){
       return byteArrayToHexString(key.getEncoded());
   }

   public void setStringToKey(String keyText){
       setKey(keyText.getBytes());
   }

   public void setHexToKey(String hexKey){
       setKey(hexStringToByteArray(hexKey));
   }

   private void setKey(byte[] bArray){
       byte[] bText = new byte[KEY_SIZE_BITS/8];
       int end = Math.min(KEY_SIZE_BITS/8, bArray.length);
       System.arraycopy(bArray, 0, bText, 0, end);
       key = new SecretKeySpec(bText, KEY_TYPE);
   }

   public void setStringToIV(String ivText){
       setIV(ivText.getBytes());
   }

   public void setHexToIV(String hexIV){
       setIV(hexStringToByteArray(hexIV));
   }

   private void setIV(byte[] bArray){
       byte[] bText = new byte[KEY_SIZE_BITS/8];
       int end = Math.min(KEY_SIZE_BITS/8, bArray.length);
       System.arraycopy(bArray, 0, bText, 0, end);
       ivBytes = bText;
   }

    public String encrypt(String message) throws InvalidKeyException,
            IllegalBlockSizeException, BadPaddingException,
            InvalidAlgorithmParameterException {
        cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(ivBytes));
        byte[] encrypted = cipher.doFinal(message.getBytes(PLAIN_TEXT_ENCODING));
        return byteArrayToHexString(encrypted);
    }

    public String decrypt(String hexCiphertext)
            throws IllegalBlockSizeException, BadPaddingException,
            InvalidKeyException, InvalidAlgorithmParameterException,
            UnsupportedEncodingException {
        cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(ivBytes));
        byte[] dec = hexStringToByteArray(hexCiphertext);
        byte[] decrypted = cipher.doFinal(dec);
        return new String(decrypted, PLAIN_TEXT_ENCODING);
    }

    private static String byteArrayToHexString(byte[] raw) {
        StringBuilder sb = new StringBuilder(2 + raw.length * 2);
        sb.append("0x");
        for (int i = 0; i < raw.length; i++) {
            sb.append(String.format("%02X", Integer.valueOf(raw[i] & 0xFF)));
        }
        return sb.toString();
    }

   private static byte[] hexStringToByteArray(String hex) {
        Pattern replace = Pattern.compile("^0x");
        String s = replace.matcher(hex).replaceAll("");

        byte[] b = new byte[s.length() / 2];
        for (int i = 0; i < b.length; i++){
          int index = i * 2;
          int v = Integer.parseInt(s.substring(index, index + 2), 16);
          b[i] = (byte)v;
        }
        return b;
   }

}

Answer 1

重写，内嵌评论。有趣的是，最大的错误是生成十六进制，所以我重写了该方法。它并不完美，但我尽可能保留了您的原始来源。

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.security.GeneralSecurityException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Security;
import java.util.regex.Pattern;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.bouncycastle.jce.provider.BouncyCastleProvider;

/*
 * Add state handling! Don't allow same key/iv for encrypting different cipher text!
 */
public class AES {

    private static Charset PLAIN_TEXT_ENCODING = Charset.forName("UTF-8"); 
    private static String CIPHER_TRANSFORMATION = "AES/CTR/NoPadding";
    private static String KEY_TYPE = "AES";
    // 192 and 256 bits may not be available
    private static int KEY_SIZE_BITS = 128;

    private Cipher cipher;
    private SecretKey key;
    private IvParameterSpec iv;

    static {
        // only needed if the platform does not contain CTR encryption by default
        if (Security.getProvider(BouncyCastleProvider.PROVIDER_NAME) == null) {
            // only needed for some platforms I presume
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
        }
    }

    public AES() throws NoSuchAlgorithmException, NoSuchPaddingException,
            NoSuchProviderException {
        // not much use without a getter
//      final KeyGenerator kgen = KeyGenerator.getInstance(KEY_TYPE);
//      kgen.init(KEY_SIZE_BITS);
//      key = kgen.generateKey();
        cipher = Cipher.getInstance(CIPHER_TRANSFORMATION);
    }

    public void setKeyHex(String keyText) {

        byte[] bText = hexStringToByteArray(keyText);
        if (bText.length * Byte.SIZE != KEY_SIZE_BITS) {
            throw new IllegalArgumentException(
                    "Wrong key size, expecting " + KEY_SIZE_BITS / Byte.SIZE + " bytes in hex");
        }
        key = new SecretKeySpec(bText, KEY_TYPE);
    }

    public void setIVHex(String ivText) {
        byte[] bText = hexStringToByteArray(ivText);
        if (bText.length != cipher.getBlockSize()) {
            throw new IllegalArgumentException(
                    "Wrong IV size, expecting " + cipher.getBlockSize() + " bytes in hex");
        }
        iv = new IvParameterSpec(bText);
    }

    public String encrypt(String message) throws InvalidKeyException,
            IllegalBlockSizeException, BadPaddingException,
            InvalidAlgorithmParameterException {
        cipher.init(Cipher.ENCRYPT_MODE, key, iv);
        byte[] encrypted = cipher.doFinal(message.getBytes(PLAIN_TEXT_ENCODING));
        return byteArrayToHexString(encrypted);
    }

    public String decrypt(String hexCiphertext)
            throws IllegalBlockSizeException, BadPaddingException,
            InvalidKeyException, InvalidAlgorithmParameterException,
            UnsupportedEncodingException {
        cipher.init(Cipher.DECRYPT_MODE, key, iv);
        byte[] dec = hexStringToByteArray(hexCiphertext);
        byte[] decrypted = cipher.doFinal(dec);
        return new String(decrypted, PLAIN_TEXT_ENCODING);
    }

    private static String byteArrayToHexString(byte[] raw) {
        StringBuilder sb = new StringBuilder(2 + raw.length * 2);
        sb.append("0x");
        for (int i = 0; i < raw.length; i++) {
            sb.append(String.format("%02X", Integer.valueOf(raw[i] & 0xFF)));
        }
        return sb.toString();
    }

    // better add some input validation
    private static byte[] hexStringToByteArray(String hex) {
        Pattern replace = Pattern.compile("^0x");
        String s = replace.matcher(hex).replaceAll("");

        byte[] b = new byte[s.length() / 2];
        for (int i = 0; i < b.length; i++) {
            int index = i * 2;
            int v = Integer.parseInt(s.substring(index, index + 2), 16);
            b[i] = (byte) v;
        }
        return b;
    }

    public static void main(String[] args) {
        try {
            String key = "0x000102030405060708090A0B0C0D0E0F";
            String iv = "0x000102030405060708090A0B0C0D0E0F";

            String text = "Owlsteads answer";
            AES aes = new AES();
            aes.setKeyHex(key);
            aes.setIVHex(iv);
            String cipherHex = aes.encrypt(text);
            System.out.println(cipherHex);
            String deciphered = aes.decrypt(cipherHex);
            System.out.println(deciphered);
        } catch (GeneralSecurityException e) {
            throw new IllegalStateException("Something is rotten in the state of Denmark", e);
        } catch (UnsupportedEncodingException e) {
            // not always thrown even if decryption fails, add integrity check such as MAC
            throw new IllegalStateException("Decryption and/or decoding plain text message failed", e);
        }
    }
}

Answer 2

您的 byteArrayToHexString 方法已损坏。 Integer.toHexString 不会添加填充零，但您的代码假设它会添加。到十六进制的损坏转换会损坏加密的字符串，而从十六进制转换回原始字节字符串会进一步损坏它。