splitting binary file into chunks

[Kurt Kaufman]

Does anyone have a suggestion as to the most efficient way to:
(1) Open a binary file (generally less than 100KB in size)

(2) look for specific byte-sequences in that file (using offset? -or is 
that just for text?)

(3) split the data into sections based on location of the 
byte-sequences in (2)

(4) decode the sections determined in (3) and place the (now text) data 
into fields

Perhaps the decoding should be done at the outset (i.e. before (2)).

Thank you,
Kurt