Anonymous ID: bd66c8 June 5, 2018, 10:42 p.m. No.1647314   🗄️.is 🔗kun   >>7321

>>1647302

 

A book cipher is a cipher in which the key is some aspect of a book or other piece of text. Books, being common and widely available in modern times, are more convenient for this use than objects made specifically for cryptographic purposes. - https://en.wikipedia.org/wiki/Book_cipher