Book Ciphers
The trouble with book ciphers is that the interceptor can look at your encrypted text and come up with a custom 'book' as the key to claim that you sent whatever it is they want to pin on you.
The trouble with book ciphers is that the interceptor can look at your encrypted text and come up with a custom 'book' as the key to claim that you sent whatever it is they want to pin on you.