# Tagged Questions

33 views

### Let N be known and d such that 3d = 1 mod phi(n)

Let N = pq be a product of two distinct primes. Show that if N and an integer d such that 3 · d = 1 mod φ(N ) are known, then it is possible to compute p and q in polynomial time.
74 views

### Generating Diffie-Hellman parameters efficiently

I am working on an Android project for school and I am supposed to do a DHKE (Diffie Hellman Key Exchange). Everything works well. The problem is that it takes a lot of time (really a lot) to ...
### Solving hard problems in $\mathbb Z_{p}^{*}$ when $\mathbb p$ is close to $\mathbb 2^{n}$
Suppose, for some security parameter $n$ you choose a prime $p$ such that $p = 2^n+c$ for some relatively small $|c| < 2^m << 2^n$. I have seen such primes being called Pseudo-Mersenne Primes ...
### Are safe primes $p=2^k \pm s$ with $s$ small less recommandable than others as a discrete log modulus?
I take the definition of safe prime as: a prime $p$ is safe when $(p-1)/2$ is prime. Safe primes of appropriate size are the standard choice for the modulus of cryptosystems related to the discrete ...