good morning,

encrypt: c = m^3 (mod 101)

decrypt: m = c^d (mod 101)

how would i solve for d (with the most efficient method by hand)?

thanks...

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- Jun 10th 2008, 06:56 AMcryptocrowModular Logs
good morning,

encrypt: c = m^3 (mod 101)

decrypt: m = c^d (mod 101)

how would i solve for d (with the most efficient method by hand)?

thanks... - Jun 10th 2008, 07:32 AMMoo
Hello,

So d is such that

Euler's theorem :

Here, n=101 and is prime.

3d has to be congruent to , i.e.

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Why ?

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So we want to find the inverse of 3 modulo 100.

But you have to be careful, because either I've confused myself, either this is a particular case. In general, the number which would be at the same place as 101 is rarely prime. - Jun 10th 2008, 07:42 AMcryptocrow
thank's a lot for the detailed info!