@typhlosion aaaa; some of us use that book as a one-time pad!
Further SCP idea: calculations and other references to the book's contents magically update in response to the book's contents changing. Messages, decrypted with the book one way, now decrypt the same way, but the ciphertext changes.
@glowingskull what i'm wondering is, if that was how it worked, how would anyone notice it?
@glowingskull i suppose. but under another interpretation, shouldn't memorization count as a calculation (of the identity function, stored in memory)?