On Oct 2, 2013, at 10:46 AM, Viktor Dukhovni <cryptogra...@dukhovni.org> wrote: >> Text encodings are easy to read but very difficult to specify >> boundaries in without ambiguity. > > Yes, and not just boundaries. Always keep in mind - when you argue for "easy readability" - that one of COBOL's design goals was for programs to be readable and understandable by non-programmers. (There's an *immense* amount of history and sociology and assumptions about how businesses should be managed hidden under that goal. One could write a large article, and probably a book, starting from there.)
My favorite more recent example of the pitfalls is TL1, a language and protocol used to managed high-end telecom equipment. TL1 has a completely rigorous syntax definition, but is supposed to be readable. This leads to such wonderful features as that SPACE is syntactically significant, and SPACE SPACE sometimes means something different from just SPACE. I have no idea if TL1 messages have a well-defined canonical form. I doubt it. Correct TL1 parsers are complicated and if you need one it's generally best to bite the bullet and pay to buy one from an established vendor. Alternatively, you can go to http://telecom-info.telcordia.com/site-cgi/ido/docs.cgi?ID=SEARCH&DOCUMENT=GR-831&; and pay $728 for a document that appears to be less than 50 pages long. Oh, and you "may wish to refer" to 6 other documents available at similarly reasonable prices. -- Jerry _______________________________________________ The cryptography mailing list cryptography@metzdowd.com http://www.metzdowd.com/mailman/listinfo/cryptography
