You cannot quote a line to avoid a boundary clash. You have to pick a
marker that does not appear. In practice this is not a problem to do.
You can scan the message if you want to be 100% sure, but use of
relatively simple algorithms will generate a line for you that will
clash with arbitrarily low probability. I chose an approach that will
generate a conflict about one time in 1E38. If you look at the reliability
of the checksums on a typical network, you'll find that 1E38 might as
well be zero -- you'll lose a boundary marker to a network erro more
often than you'll gain one from a false match.
I don't see how its possible to guarantee your algorithm will have
a conflict one time in 1E38 unless you scan the message or
make assumptions about whats in the message. Unless your
algorithm remains secret, someone could compose
a message of strings likely to be generated by the algorithm.
+------------------------------------+--------------------------------------+
| James H. Thompson | jimmy_t(_at_)verifone(_dot_)com
(Internet) |
| VeriFone Inc. | uunet!verifone!jimmy_t (UUCP) |
| 100 Kahelu Avenue | 808-623-2911 (Phone) |
| Mililani, HI 96789 | |
+------------------------------------+--------------------------------------+