On Sat, Jun 7, 2014 at 6:52 AM, gnugu <[email protected]> wrote:
> Hi I am getting the following exception, when decrypting a file on Android
> based on user supplied password:
>
> Caused by: java.lang.ArrayIndexOutOfBoundsException: src.length=1024
> srcPos=1008 dst.length=16 dstPos=16 length=16
> at java.lang.System.arraycopy(Native Method)
> at
> com.android.org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher.processBytes(PaddedBufferedBlockCipher.java:221)
> at
> com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher$BufferedGenericBlockCipher.processBytes(BaseBlockCipher.java:882)
> at
> com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineUpdate(BaseBlockCipher.java:674)
> at javax.crypto.Cipher.update(Cipher.java:893)
> at javax.crypto.CipherOutputStream.write(CipherOutputStream.java:95)
>
> It happens randomly and from the crash reports on Google Play Store only on
> Android 4+. It used to work on older versions.
>
> My Crypto wrapper:
>
> private static final String CIPHER_PROVIDER = "AES";
> _cipher = Cipher.getInstance(CIPHER_PROVIDER);
This may have different results on different providers/versions. The
default cypto
provider in newer version of Android is based AndroidOpenSSL, but previous
versions used BouncyCastle. The proper way to fix this is to specify the
full Cipher transformation instead of just "AES" ("AES/CBC/PKCS5", etc.).
Then you'll need to deal with IVs properly, of course.
You could probably get away for now with explicitly specifying the BouncyCastle
provider with something like this to get the same behaviour as before:
_cipher = Cipher.getInstance(CIPHER_PROVIDER, "BC");
>
> When I changed the code to this:
>
...
> byte[] buffer = new byte[BUFFER_SIZE];
> int count = -1;
> while ((count = input.read(buffer)) != -1) {
>
> byte[] result = null;
> if (count == BUFFER_SIZE) {
> result = _cipher.update(buffer, 0, count);
> } else {
> result = _cipher.doFinal(buffer, 0, count);
> }
>
> if (result != null) {
> output.write(result);
> }
...
>
> I'm getting
>
> javax.crypto.BadPaddingException: pad block corrupted
>
You should only write as many bytes as you read, otherwise
you get garbage. In any case, using raw buffers doesn't fix
your main problem, so see above.
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