# Who invented the $1^n$ notation? [duplicate]

I am always wondering about the seemingly odd syntax $1^n$ which designates the security strength of a cryptographic algorithm.

Who invented this (odd) syntax and what was the reason for inventing it?

• It definitely comes from theory, and specifically formal language theory, which means it really comes from mathematical logic. If I had to guess, I'd say S.C. Kleene or Church are likely culprits. – pg1989 Jun 23 '16 at 17:29
• It's not odd at all, it's the string '1' concatenated with itself n times. – fkraiem Jun 23 '16 at 18:02
• @fkraiem That's odd by definition, isn't it? – Maarten Bodewes Jun 23 '16 at 19:51
• @MaartenBodewes Well that depends on your encoding. Usually it's a unary representation of the security parameter, so it's odd if and only if $n$ is odd. – fkraiem Jun 23 '16 at 19:58