This is my hackish attempt to learn / understand secure(ish) sending of post data. Constructive criticism welcome.
This is just theory, not much code. Also, I'm using PHP's SHA1() in the examples, only because I have put time in understanding its internals. I know theres other (better?) algorithms (example: MD5()) so swap out for your favorite.
1) Server generates a random salt rand(min, max), sends it with the page upon request, computes and stores the SHA1(un:pw:salt) along with the server timestamp of the request (to a database)
1a) Note : salt is sniffable, so assume hacker knows salt (can you un-SHA1() something, to get the SHA1'd data out?)
2) User inputs username and password clicks submit
3) Submit fires a JavaScript function (packed for obfuscation, yeah I know, this does not add true security) that SHA1(un:pw:salt), then posts only that result to the server
3a) Note : encrypted credential is sniffable
4) Server checks that the received credentials match what it stored in the database, and arrive within a timeframe (5 min or so) since the initial request. allow / deny decision is made.
Further requests alter the salt, so even if someone sniffed the encrypted data, it would be useless after a) user makes new page request b) timeframe expires
Thoughts?
Edit: also, assume all the strip tags / SQL hacks / < > etc... injections are dealt with appropriately.
