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?

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    $\begingroup$ 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. $\endgroup$ – pg1989 Jun 23 '16 at 17:29
  • $\begingroup$ It's not odd at all, it's the string '1' concatenated with itself n times. $\endgroup$ – fkraiem Jun 23 '16 at 18:02
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    $\begingroup$ @fkraiem That's odd by definition, isn't it? $\endgroup$ – Maarten Bodewes Jun 23 '16 at 19:51
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    $\begingroup$ @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. $\endgroup$ – fkraiem Jun 23 '16 at 19:58