Score:1

Diffie-Hellman Assumption

yt flag

I'm wondering if the following problem is as hard as computational or decision Diffie-Hellman problem? (Or is it actually an easy problem because $c$ is available?)

Given a cyclic group $G$ and let its order be $q$. Given $g$, $q$, $g^a$ and $g^b$ and $c \in Z_q$, decide if $c \equiv a*b \mod q$.

Another version of the problem could be: let $G$ be a group of unknown order (e.g., where RSA or strong RSA assumption could apply, thus computing roots would be hard).

fgrieu avatar
ng flag
I assume we are given $g$ and $q$.
poncho avatar
my flag
This problem is obviously no harder than DDH (given an Oracle that can solve DDH, it's easy to solve your problem)
Sean avatar
yt flag
Yes, given g and q. I have rephrased question correspondingly. Thanks!
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