字符串加密和解密的Android密鑰比較

Question

我加密和使用此代碼

public class Encryption { 
private static String charsetName = "UTF8"; 
private static String algorithm = "DES"; 
private static int base64Mode = Base64.DEFAULT; 

public String getCharsetName() { 
    return charsetName; 
} 

public void setCharsetName(String charsetName) { 
    this.charsetName = charsetName; 
} 

public String getAlgorithm() { 
    return algorithm; 
} 

public void setAlgorithm(String algorithm) { 
    this.algorithm = algorithm; 
} 

public int getBase64Mode() { 
    return base64Mode; 
} 

public void setBase64Mode(int base64Mode) { 
    this.base64Mode = base64Mode; 
} 

public static String encrypt(String key, String data) { 
    if (key == null || data == null) 
     return null; 
    try { 
     DESKeySpec desKeySpec = new DESKeySpec(key.getBytes(charsetName)); 
     SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance(algorithm); 
     SecretKey secretKey = secretKeyFactory.generateSecret(desKeySpec); 
     byte[] dataBytes = data.getBytes(charsetName); 
     Cipher cipher = Cipher.getInstance(algorithm); 
     cipher.init(Cipher.ENCRYPT_MODE, secretKey); 
     return Base64.encodeToString(cipher.doFinal(dataBytes), base64Mode); 
    } catch (Exception e) { 
     return null; 
    } 
} 

public static String decrypt(String key, String data) { 
    if (key == null || data == null) 
     return null; 
    try { 
     byte[] dataBytes = Base64.decode(data, base64Mode); 
     DESKeySpec desKeySpec = new DESKeySpec(key.getBytes(charsetName)); 
     SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance(algorithm); 
     SecretKey secretKey = secretKeyFactory.generateSecret(desKeySpec); 
     Cipher cipher = Cipher.getInstance(algorithm); 
     cipher.init(Cipher.DECRYPT_MODE, secretKey); 
     byte[] dataBytesDecrypted = (cipher.doFinal(dataBytes)); 
     return new String(dataBytesDecrypted); 
    } catch (Exception e) { 
     return null; 
    } 
} 

} 

我想匹配的關鍵是我放置加密解密&文本，如果雙方之前解密鑰匙匹配解密文中另有提示我這裏的wrongkey就是我試圖做

string a="sfdsfsjbgdfkbgdfkjbgk";//encrypted text just for assuming 

decrypted=Encryption.decrypt(key, a.trim()); 

encrypted=Encryption.encrypt(key, decrypted.trim()); 

if(a.contentEquals(encrypted.trim())){ 
//show the decrypted text 
} 

else 
{ 
//Show the wrong key 
} 

這是如何我試圖做的，但是當我把正確的密鑰else語句執行 和應用程序停止對if語句 任何人都可以指出我在這裏做錯了什麼。

Answer 1

我無法重現您的問題。這裏是一個小SSCCE失敗來演示該問題：

（注：這將是更容易，如果你已經提供的代碼示例也是一個SSCCE）

import java.io.UnsupportedEncodingException; 
import java.security.GeneralSecurityException; 

import android.util.Base64 

import javax.crypto.Cipher; 
import javax.crypto.SecretKey; 
import javax.crypto.SecretKeyFactory; 
import javax.crypto.spec.DESKeySpec; 

public class EncryptDecryptTest { 

    public static void main(String[] args) throws Exception { 
    String key = "12345678"; 
    String ciphertext = encrypt(key, "foo"); 

    String decrypted = decrypt(key, ciphertext.trim()); 
    String encrypted = encrypt(key, decrypted.trim()); 

    if (ciphertext.contentEquals(encrypted.trim())) { 
     System.out.println("decrypted!"); 
    } else { 
     System.out.println("wrong key!"); 
    } 
    } 

    public static String encrypt(String key, String data) 
     throws GeneralSecurityException, UnsupportedEncodingException { 
    DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF8")); 
    SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("DES"); 
    SecretKey secretKey = secretKeyFactory.generateSecret(desKeySpec); 
    byte[] dataBytes = data.getBytes("UTF8"); 
    Cipher cipher = Cipher.getInstance("DES"); 
    cipher.init(Cipher.ENCRYPT_MODE, secretKey); 
    return Base64.encodeToString(cipher.doFinal(dataBytes), Base64.DEFAULT); 
    } 

    public static String decrypt(String key, String data) 
     throws GeneralSecurityException, UnsupportedEncodingException { 
    byte[] dataBytes = Base64.decode(data, Base64.DEFAULT); 
    DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF8")); 
    SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("DES"); 
    SecretKey secretKey = secretKeyFactory.generateSecret(desKeySpec); 
    Cipher cipher = Cipher.getInstance("DES"); 
    cipher.init(Cipher.DECRYPT_MODE, secretKey); 
    byte[] dataBytesDecrypted = (cipher.doFinal(dataBytes)); 
    return new String(dataBytesDecrypted); 
    }  
} 

對於我來說，這個打印如預期的那樣出decrypted!。請注意，我使用標準Java（不是Android）執行了我的測試，但我試圖修復要在Android上執行的代碼。

一些端註釋：

• 你的trim()持續使用似乎有些奇怪。它似乎沒有實現任何東西。
• 當您只使用equals()時，您使用contentEquals()。
• 指定DES作爲算法，將密碼模式和填充作爲默認值。你真的應該明確指出這兩者。
• DES太弱，無法提供任何安全性，因此您可能需要考慮轉向更強大的算法。