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The Diffie-Hellman key exchange is being used to establish a secret key, k, between
Alice and Bob. Alice sends Bob (227, 5, 82). Bob responds with (125).
Alice’s secret number, x, is 12, and Bob’s secret number, y, is 3.
The secret key value k is

I worked like this

$since, x=12$ and $0 \leq x \leq p-1$, so p must be either of 227 or 82 and the other value should be $g^xmod\,p$

So, I got p=227,g=5 and Alice sent to Bob=82 which is $g^x mod\,p$

$y=3$, so $82^3mod \,227=212(=Secret\,Key\,K)$

But the answer is given to be 155.