Android - Crittografy Chiffrement décryptage ne fonctionne pas

Question

J'ai besoin de crypter une chaîne, puis décrypter. La fonction crypter fonctionne bien, mais quand je passe la valeur cryptée à la fonction décryptage, je reçois une exception de pointeur nul. Si j'utilise le même code dans l'application Java, tout fonctionne bien.

public class Cripthografy { 
private static String TAG="freeliberomail"; 

public static String encrypt(String seed, String cleartext){ 
    byte[] rawKey; 
    byte[] result=null; 
try { 
rawKey = getRawKey(seed.getBytes()); 

    result = encrypt(rawKey, cleartext.getBytes()); 
    } catch (Exception e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } 
    return toHex(result); 
    } 

    public static String decrypt(String seed, String encrypted) { 
    byte[] rawKey; 
    byte[] result=null; 
    try { 
rawKey = getRawKey(seed.getBytes()); 

    byte[] enc = toByte(encrypted); 
    result = decrypt(rawKey, enc); 
    } catch (Exception e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } 
    return new String(result); 
    } 


    private static byte[] getRawKey(byte[] seed) throws Exception { 
     KeyGenerator kgen = KeyGenerator.getInstance("AES"); 
     SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); 
     sr.setSeed(seed); 
     kgen.init(128, sr); // 192 and 256 bits may not be available 
     SecretKey skey = kgen.generateKey(); 
     byte[] raw = skey.getEncoded(); 
     return raw; 
    } 
    private static byte[] encrypt(byte[] raw, byte[] clear){ 
byte[] encrypted=null; 
     SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); 
     Cipher cipher; 
    try { 
cipher = Cipher.getInstance("AES"); 
    cipher.init(Cipher.ENCRYPT_MODE, skeySpec); 
    encrypted = cipher.doFinal(clear); 
    } catch (NoSuchAlgorithmException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } catch (NoSuchPaddingException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } catch (InvalidKeyException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } catch (IllegalBlockSizeException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } catch (BadPaddingException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } 
    return encrypted; 
    } 


    private static byte[] decrypt(byte[] raw, byte[] encrypted) { 
byte[] decrypted = null; 
    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); 
    Cipher cipher; 
    try { 
cipher = Cipher.getInstance("AES"); 
    cipher.init(Cipher.DECRYPT_MODE, skeySpec); 
    decrypted = cipher.doFinal(encrypted); 
    }catch (NoSuchAlgorithmException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
     } catch (NoSuchPaddingException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
     } catch (InvalidKeyException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } catch (IllegalBlockSizeException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } catch (BadPaddingException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
    } 

    return decrypted; 
    } 


    public static String toHex(String txt) { 
    return toHex(txt.getBytes()); 
    } 

public static String fromHex(String hex) { 
return new String(toByte(hex)); 
} 

public static byte[] toByte(String hexString) { 
    int len = hexString.length()/2; 
    byte[] result = new byte[len]; 
    for (int i = 0; i < len; i++) 
    result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue(); 
    return result; 
} 


    public static String toHex(byte[] buf) { 
    if (buf == null) 
    return ""; 
    StringBuffer result = new StringBuffer(2*buf.length); 
     for (int i = 0; i < buf.length; i++) { 
     appendHex(result, buf[i]); 
    } 
    return result.toString(); 
    } 
    private final static String HEX = "ABCDEF"; 
    private static void appendHex(StringBuffer sb, byte b) { 
    sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f)); 
    } 

} 

Puis-je appeler:

  String encValue=Cripthografy.encrypt("MY_KEY", "helloworld"); 
     String decValue=Cripthografy.decrypt("MY_KEY", encValue); 
     Log.d(TAG,"encript:"+encValue+" "+"decript:"+decValue); 

Exception est:

 01-17 03:57:23.986: W/System.err(29846): javax.crypto.BadPaddingException: pad  block corrupted 
     01-17 03:57:23.991: W/System.err(29846):  at  com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(B   aseBlockCipher.java:709) 
     01-17 03:57:23.991: W/System.err(29846):  at  javax.crypto.Cipher.doFinal(Cipher.java:1111) 
     01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Cripthografy.decrypt(Cripthografy.java:111) 
     01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Cripthografy.decrypt(Cripthografy.java:55) 
     01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.writeCookieTofile(Auth.java:307) 
     01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.createSessionCookie(Auth.java:287) 
     01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.scenario(Auth.java:196) 
     01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.accessMail(Auth.java:117) 
     01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.run(Auth.java:96) 
     01-17 03:57:23.991: W/System.err(29846):  at java.lang.Thread.run(Thread.java:856) 
     01-17 03:57:23.996: W/dalvikvm(29846): threadid=11: thread exiting with uncaught exception (group=0x41584930) 
      01-17 03:57:23.996: E/AndroidRuntime(29846): FATAL EXCEPTION: Thread-32785 
      01-17 03:57:23.996: E/AndroidRuntime(29846): java.lang.NullPointerException 
      01-17 03:57:23.996: E/AndroidRuntime(29846): at java.lang.String.<init>(String.java:141) 
      01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Cripthografy.decrypt(Cripthografy.java:60) 
      01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.writeCookieTofile(Auth.java:307) 
      01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.createSessionCookie(Auth.java:287) 
      01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.scenario(Auth.java:196) 
      01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.accessMail(Auth.java:117) 
      01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.run(Auth.java:96) 
      01-17 03:57:23.996: E/AndroidRuntime(29846): at java.lang.Thread.run(Thread.java:856) 

Answer 1

oui, android Cipher a quelques problèmes. L'un est que l'octet [] dans cipher.doFinal (crypté) doit parfois avoir la bonne longueur. Essayez de nourrir avec un tableau chiffré de 128 bits (remplir des 0?)

après de nombreuses heures douloureuses cet exemple fonctionne enfin:

private static byte[] key = "12345678".getBytes();// 64 bit 
private static byte[] iv = "12345678".getBytes(); 

public static String encrypt(String in) { 
    String cypert = in; 
    try { 
     IvParameterSpec ivSpec = new IvParameterSpec(iv); 
     SecretKeySpec k = new SecretKeySpec(key, "DES"); 
     Cipher c = Cipher.getInstance("DES/CBC/PKCS7Padding"); 
     c.init(Cipher.ENCRYPT_MODE, k, ivSpec); 
     byte[] encryptedData = c.doFinal(in.getBytes()); 
     cypert = Base64.encodeLines(encryptedData); 
    } catch (Exception e) { 
     Debugger.error(e); 
    } 
    return cypert; 
} 


public static String decrypt(String in) throws Exception { 
    String plain=in; 
    try { 
     IvParameterSpec ivSpec = new IvParameterSpec(iv); 
     SecretKeySpec keys = new SecretKeySpec(key, "DES"); 
     Cipher cipher = Cipher.getInstance("DES/CBC/PKCS7Padding"); 
     cipher.init(Cipher.DECRYPT_MODE, keys, ivSpec); 
     // decryption pass 
     byte[] cipherText = Base64.decodeLines(in); 
     int ctLength = cipherText.length; 
     byte[] plainText = new byte[cipher.getOutputSize(ctLength)]; 
     ByteArrayOutputStream bos = new ByteArrayOutputStream(); 
     bos.write(cipher.doFinal(cipherText)); 
     plainText = bos.toByteArray(); 
     bos.close(); 
     plain = new String(plainText, "UTF8"); 
    } catch (Exception e) { 
     Debugger.error(e); 
    } 
    return plain; 
}