15
$\begingroup$

In J. E. Littlewood's, "A Mathematicians Miscellany" there is the following passage about ciphers. I found it interesting for a couple of reasons.

First of all the "legend that every cipher is breakable" is something that is certainly not a common belief nowadays and it makes me wonder why it was back then.

Secondly I have no knowledge of cryptography and I would be very interested in hearing from someone more specialized what are the weak points of Littlewood's proposed cipher (I guess it cannot hold up to modern standards)

In particular his claim that a single message cannot be unscrambled "even if all were known except the key number $N$" is it true with modern computing power ?
enter image description here

Improve this question
$\endgroup$
4
  • 3
    $\begingroup$ In general, hsm.stackexchange.com might be a more appropriate venue for such questions $\endgroup$
    – Jules Lamers
    Commented May 1 at 16:01
  • $\begingroup$ @JulesLamers That's interesting, I would have thought security.stackexchange.com for this example. $\endgroup$
    – preferred_anon
    Commented May 3 at 8:22
  • 1
    $\begingroup$ There's also the Cryptography Stack Exchange. $\endgroup$
    – Timothy Chow
    Commented May 3 at 12:28
  • 2
    $\begingroup$ Regarding the "legend that every cipher is breakable," I'm reminded of a comment that Sherlock Holmes made in "The Adventure of the Dancing Men": "What one man can invent another can discover." Certainly at the time Littlewood was writing, mankind's collective knowledge of cryptography was much more primitive than it is today, and the "legend" would have been more plausible. $\endgroup$
    – Timothy Chow
    Commented May 3 at 12:34

1 Answer 1

Reset to default
25
$\begingroup$

Littlewood's cypher is a one-time-pad, which would be unbreakable if fed by a true random number generator, but Littlewood's pseudo-random number generator is broken. See Breaking Littlewood's cypher by Damien Stehlé (2003).

Improve this answer
$\endgroup$
0

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .