Cryptography Existence of a reasonably strong cipher that can be executed in your head?

Existence of a reasonably strong cipher that can be executed in your head?
W3C Hits Milestone with Web Authentication specification
I dream a social network where anything is under VPN, tor and End-toEnd encryption. What about you?
Umbral: a threshold proxy re-encryption scheme
Default chain mode for AES

Existence of a reasonably strong cipher that can be executed in your head?

Posted: 21 Mar 2018 11:36 AM PDT

I have really been pondering on this question for a while (and even had some sketches I designed which are looking pretty bleak so far). Here I'll write a quick post outlining what my thoughts are

The motivation

The idea is that we assume that all electronic devices are monitored by some undesirable third party (e.g. the FBI), and every point in space is also monitored (via camera for instance) by the FBI (making executing a cipher on a piece of paper useless). Can a cipher with lowered security parameters still be somewhat feasible for a human to compute exist? (It can be very hard - such as keeping 80 bits in your head, but possible with extensive training).

The 'threat model'

The following is assumed:

The key is indistinguishable from random (not letters of a password, e.t.c.)
Chosen plaintext attacks are impossible (theoretically you could execute indirect chosen plaintext attacks - such as by causing an incident, but this is not considered)
Known plaintext attacks ARE possible
No more than N (where N is a small number) plaintexts will be encrypted with the scheme (for instance you could set N to be 10 and declare that the cipher is secure with 10 such messages)
No part of the key is leaked at any time
Computations happening in your head are impossible to analyze
The attacker has complete and extensive knowledge of the algorithm used, both for encryption and decryption
The attacker is so smart that he can always tell when you are encrypting or decrypting things by a physical action (when you do anything with a deck of cards, or write something on paper the attacker always magically knows whether you are doing it to encrypt/decrypt or not)

Under the above (incomplete for now) the cipher should be secure (indistinguishable from a random function of the input, e.t.c. I don't need to repeat this I'm sure you know what I mean)

submitted by /u/naclo3samuel
[link] [comments]

W3C Hits Milestone with Web Authentication specification

Posted: 21 Mar 2018 05:29 AM PDT

submitted by /u/johnmountain
[link] [comments]

I dream a social network where anything is under VPN, tor and End-toEnd encryption. What about you?

Posted: 22 Mar 2018 12:39 AM PDT

submitted by /u/RedditGuest_2018
[link] [comments]

Umbral: a threshold proxy re-encryption scheme

Posted: 21 Mar 2018 07:43 AM PDT

submitted by /u/michwill
[link] [comments]

Default chain mode for AES

Posted: 21 Mar 2018 12:11 PM PDT