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2d
comment Describe a fast (polynomial time)algorithm who takes as input the elements $g^a,g^b$ and gives as output the element $g^{a \cdot b}$
Note that $h^{-1} = h^{q-1}$, and so we don't need to spell out the requirement that we can perform inversion explicitly (because we can compute $h^{q-1}$, if a more efficient method isn't available..
2d
awarded  Supporter
Jul
8
comment Find all numbes $1\le a\le n-1$ which are prime to n and they are not witness Fermat of compositeness of n
@paris: they all have $a^{34} = 1 \pmod{35}$, and hence they are not Fermat witnesses. Reminder: the Fermat test for compositeness is $a^{n-1} \ne 1 \pmod{n}$; if we find an $a \ne 0 \pmod{n}$ where this is true, then we've shown that $n$ is composite. An $a$ that doesn't show this is a Fermat nonwitness.
Jul
8
awarded  Teacher
Jul
8
answered Find all numbes $1\le a\le n-1$ which are prime to n and they are not witness Fermat of compositeness of n
Jul
7
awarded  Informed
Jul
7
answered Reversing Rotation + XOR
Dec
4
comment Quasi-linear time fully homomorphic encryption using p-adic ring homomorphism
A warning about the paper: it doesn't sound like the author knows much about crypto. There's the misrepresentation of FHE that Mike pointed out; in addition, he claims his system is Informationally Secure (which is impossible for any public key system); he claims that a message cannot be uniquely decrypted; if this were true, this would imply that someone with the private key cannot decrypt it. His claim of $O(n \log n)$ time is also bogus. I would approach this system only with extreme caution.