Bit-by-bit Files

I am playing about with some encryption that requires you to swap the positions of bits within a block. I thought the best way would be to use an array of booleans or a bitset.
The algorithm for the actual encryption is pretty easy but I need to create an array of 'bits' directly from a file.
All the streams i seem to find use bytes only and don't really want to convert from this. Any suggestions?