IMS_Blog

Following on from my last post the entire encryption scheme did leave me with one problem..post titles. The titles themselves can give something away about the post content (well, sometimes). It wasn’t so easy to simply encrypt them though, due to the whole multiple key for a single post possibility if nothing else (not to mention the length of an encrypted title would be far too long!). So now the enctyption mechanism takes the title and puts it in a <span> within the post body before encrypting. The title is set to Encrypted Post with the date appended. Decryption decrypts everything and finds the span, replacing the title with its contents (and removing the span). This actually means I can have different titles depending which part of a post is decrypted if there’s more than one key!

Oh, and so that it’s more obvious which keys may work, there’s now an indication of who may decrypt. So if I were to ever use this I could dish out a single key to friends and they’d be able to use that to decrypt everything marked as decryptable by friends (of course this whole scheme suffers from the classic key distribution problem but hey, if I really was bothered I could set up public-private key encryption with people to exchange keys…but then, if you’ve gone so far as to do that…)

Yes, I have spent far too much time on this!