Android : Reading bytes from large files in Android.

I'm developing an android application in which I'm using the SMS4 algorithm. I use this algorithm to encrypt or decrypt files. The problem arises when I'm trying to encrypt /decrypt large files. The application crashes when I try to encrypt/decrypt file > 1mb. So, please let me know how to implement this algorithm efficiently in Android, also suggest any library like apache commons or guava so I don't have to reinvent wheels. Thanks