Um, how about encoding into ascii somehow and doing a regex on that? It should work. I've had enough wierd things crop up with binary code in the past that I'm paranoid on this issue (unless it's in C, in which case I'm both more at ease and more paranoid if that makes sense).

I've not used utf8 regex in the past but if I want to compare Japanese strings I change the character encoding into a 7-bit encoding (EUC for Japanese, which is two byte and preserves ascii codes), so maybe MIME::Base64 or some other packing method for the general case?

I believe that JPerl, a Japanized Perl, actually lets you do tr// and things with binary but this all seems pretty iffy, seems best to me to do something you know must work, though maybe not so elegant. Then test anyway. :)

By the way I don't know where your binary is coming from but watch out for endianness, which means that if you are reading a resource file from a Mac it probably stores a two or four byte value in the reverse order that a PC does. But if it is just an 8 bit ISO standard that problem shouldn't arise.