Re: effective Method to calculate n-th power

William Elliot wrote:

If q is the order of g^x, then the order of g^x^n can be calculated
as I hinted in other post.  That is different than the value of g^x^n
which, knowing the order, can be 'simplified'.

How can you compute the order of g^x^n starting from the order of g^x alone??

E.g. consider the multiplicative group Z_{17}^* of order 16.
Assume that the other given data is g^x=4 and n=3.
Now we could have
A) g=2,x=2, so the answer would be g^x^n=2^8=1 (mod 17),
   an element of order 1, or
B) g=4,x=1, so the answer would be g^x^n=4^1=4 (mod 17),
   an element of order 4.

Do you now see that we are given insufficient information?

Cheers,

Jyrki

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