question: public int processByte ( byte in , byte [ ] out , int outOff ) throws DataLengthException , IllegalStateException { int resultLen = 0 ; if ( bufOff == buf . length ) { resultLen = cipher . processBlock ( buf , 0 , out , outOff ) ; System . arraycopy ( buf , blockSize , buf , 0 , blockSize ) ; bufOff = blockSize ; } buf [ bufOff ++ ] = in ; return resultLen ; }
target:  process a single byte, producing an output block if necessary.