javax.crypto.IllegalBlockSizeException: last block incomplete in decryption exception

问题

I am trying to decrypt a string in android. I keep getting the following exception:

08-21 03:56:56.700: W/System.err(4208): javax.crypto.IllegalBlockSizeException: last block incomplete in decryption
08-21 03:56:56.700: W/System.err(4208):     at com.android.org.bouncycastle.jce.provider.JCEBlockCipher.engineDoFinal(JCEBlockCipher.java:697)
08-21 03:56:56.700: W/System.err(4208):     at javax.crypto.Cipher.doFinal(Cipher.java:1106)
08-21 03:56:56.700: W/System.err(4208):     at com.dharani.android.legalplex.BusinessLayer.BLCommonOperations.decrypt(BLCommonOperations.java:284)
08-21 03:56:56.700: W/System.err(4208):     at com.dharani.android.legalplex.BusinessLayer.BLCommonOperations.decryptAndgetFailCountFromPreferences(BLCommonOperations.java:144)
08-21 03:56:56.700: W/System.err(4208):     at com.dharani.android.legalplex.PresentationLayer.TransparentActivity.onCreate(TransparentActivity.java:112)
08-21 03:56:56.700: W/System.err(4208):     at android.app.Activity.performCreate(Activity.java:4465)
08-21 03:56:56.700: W/System.err(4208):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1052)
08-21 03:56:56.700: W/System.err(4208):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1932)
08-21 03:56:56.700: W/System.err(4208):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1993)
08-21 03:56:56.700: W/System.err(4208):     at android.app.ActivityThread.access$600(ActivityThread.java:127)
08-21 03:56:56.700: W/System.err(4208):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1159)
08-21 03:56:56.700: W/System.err(4208):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-21 03:56:56.700: W/System.err(4208):     at android.os.Looper.loop(Looper.java:137)
08-21 03:56:56.700: W/System.err(4208):     at android.app.ActivityThread.main(ActivityThread.java:4507)
08-21 03:56:56.700: W/System.err(4208):     at java.lang.reflect.Method.invokeNative(Native Method)
08-21 03:56:56.700: W/System.err(4208):     at java.lang.reflect.Method.invoke(Method.java:511)
08-21 03:56:56.700: W/System.err(4208):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
08-21 03:56:56.700: W/System.err(4208):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
08-21 03:56:56.700: W/System.err(4208):     at dalvik.system.NativeStart.main(Native Method)

The encrypt and decrypt methods are:

public  String encrypt(String message) throws Exception
{
    String salt = SharedVariables.globalContext.getString(R.string.EncryptionKey);
    SecretKeySpec key = new SecretKeySpec(salt.getBytes(), "AES");
    Cipher c = Cipher.getInstance("AES");
    c.init(Cipher.ENCRYPT_MODE, key);
    byte[] encVal = c.doFinal(message.getBytes());
    String encrypted=Base64.encodeToString(encVal, Base64.DEFAULT);
    return encrypted;
}

public  String decrypt(String message) throws Exception
{
    String salt = SharedVariables.globalContext.getString(R.string.EncryptionKey);
    Cipher c = Cipher.getInstance("AES");
    SecretKeySpec key = new SecretKeySpec(salt.getBytes(), "AES");
    c.init(Cipher.DECRYPT_MODE, key);
    byte[] decordedValue = Base64.decode(message.getBytes(), Base64.DEFAULT);
    byte[] decValue = c.doFinal(decordedValue);
    String decryptedValue = new String(decValue);
    return decryptedValue;
}

回答1:

I got the solution.Following is new code that worked for me

// Encryption
public  String encrypt(String message) throws Exception
{
    String message1=Base64.encodeBytes(message.getBytes(),Base64.NO_OPTIONS);
    String salt = SharedVariables.globalContext.getString(R.string.EncryptionKey);
    SecretKeySpec key = new SecretKeySpec(salt.getBytes(), "AES");
    Cipher c = Cipher.getInstance("AES");
    c.init(Cipher.ENCRYPT_MODE, key);
    byte[] encVal = c.doFinal(message1.getBytes());
    String encrypted=Base64.encodeToString(encVal, Base64.NO_OPTIONS);
    return encrypted;
}

//Decryption    
public String decrypt(String message) throws Exception
{
    String salt = SharedVariables.globalContext.getString(R.string.EncryptionKey);
    Cipher c = Cipher.getInstance("AES");
    SecretKeySpec key = new SecretKeySpec(salt.getBytes(), "AES");
    c.init(Cipher.DECRYPT_MODE, key);
    byte[] decordedValue = Base64.decode(message.getBytes(), Base64.NO_OPTIONS);
    byte[] decValue = c.doFinal(decordedValue);
    String decryptedValue = new String(decValue);
    String decoded=new String(Base64.decode(decryptedValue,Base64.NO_OPTIONS));
    return decoded;
}

回答2:

salt.getBytes() should be salt.getBytes(UNICODE_FORMAT)

来源：https://stackoverflow.com/questions/18350459/javax-crypto-illegalblocksizeexception-last-block-incomplete-in-decryption-exce