Update crypt.php

A 1024 kilobyte key would be obnoxiously slow to operate on. I'm assuming you meant 1024-bit?

Also, 183 bytes = 1464 bits.

Here's a safe alternative: 2048 bits, with comment-code sanity
Update crypt.php

Use a 256-bit random value
Merge pull request #7807 from sarciszewski/patch-1

Update crypt.php