Property of a cryptographic function

Question

What property of a cryptographic function is described below?

B = F(A) A = F(B)

score 3 · Answer 1 · answered Mar 08 '11 at 03:23

3

$F$ is an involution. You don't want this property for a block cipher since the function doesn't look "random". On the other hand, a stream cipher works exactly that way, but then it's a bit misleading to think of it as a function $F$: the function is missing an important parameter, namely time.

answered Mar 08 '11 at 03:23

Yuval Filmus

57,157

your answer looks broken – Mar 08 '11 at 04:05
That's quite probable; in what way? – Yuval Filmus Mar 08 '11 at 04:46

score 1 · Answer 2 · answered Jun 19 '11 at 00:56

1

Most mechanical cipher machines use a reciprocal cipher, so the machine doesn't need a separate "encode mode" and "decode mode". A reciprocal cipher is an involution.

Cryptodox: reciprocal cipher
Wikipedia: reciprocal cipher

answered Jun 19 '11 at 00:56

David Cary

1,817

Property of a cryptographic function

2 Answers2