Questions tagged [safe-prime]
A safe prime is a prime number of the form 2q + 1, where q is also a prime.
53 questions
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Getting runtime down for algorithms to find safe- and Sophie-Germain primes
My algorithm's latest run found 5 (4096-bit, 1233-digit) safe or Sophie Germain primes in 6 hours and 59 minutes, after 11,190,811 attempts. It doesn't use any libraries, public or otherwise—just a ...
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Reducing modulo an unknown integer
Consider we have a large integer $n=pq$ with both $p$ and $q$ safe primes(i.e. $p=2p'+1$ $q=2q'+1$), we also select and element $w \in Z^*_{n}$ such that $|w|=\varphi(n)/4=p'q'=n'$, we also select a ...
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Safe prime modulo groups Zp quadratic residues count in DH groups RFC3526?
Let's create an example with safe primes, suppose we have a group Zp* (operation is multiplication), and where p=23, q=11 and g=2.
Then group elements are {1 2 4 8 16 9 18 13 3 6 12}, so there are ...
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Is any safe prime sufficient for a secure DH key exchange?
There are some very large safe primes listed here: https://en.wikipedia.org/wiki/Safe_and_Sophie_Germain_primes
Would using any of them result in a secure DH construction? Generator is 2.
The exponent ...
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Are Safe and Sophie Germain primes evenly distributed?
Do Safe and Sophie Germain primes maintain a relatively stable distribution as numbers get larger, or do they become rarified beyond a predictable value?
This is important in one area of triangular ...
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DHKE: Why using safe prime gives us "safe" subgroups?
I come from the question here: Safe primes subgroup in Diffie–Hellman key exchange
Where the accepted answer states that there are only 4 possible outcomes for the order of a subgroup when using a ...
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Safe primes subgroup in Diffie–Hellman key exchange
I'm trying to understand how the safe primes numbers are used in Diffie–Hellman key exchange. According to wiki:
The order of G should have a large prime factor to prevent use of the
Pohlig–Hellman ...
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Optimize the speed of a safe prime finder in C
I am trying to implement the Schnorr’s identification protocol in C. I need a safe prime in order to be able to find a generator of the cyclic group efficiently. The problem is that my program takes ...
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DDH hardness with shared public parameters
DDH is believed hard for subgroup of $ℤ^*_p$ with order $q=(p-1)/2$ when $p$ is a safe prime chosen randomly.
What if $p$ isn't random: When parameters are shared, $p$ mightn't have been chosen ...
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What is the purpose of "q" in Safe Prime definition during key pair generation?
Consider the following case, given x(private key) and y(public key), how to determine whether this key pair is generated by a pre-defined Safe Prime Group(Say FFDHE, RFC 7919)?
In context of SP800 ...
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How does Diogenes prove equivalence of discreet logs despite the candidates not being composed of safe primes
In the paper describing a protocol for distributed RSA modulus generation, Diogenes, "[they] employ a special-purpose $\Sigma$-protocol based on [Sho00] for proving correctness of exponentiations ...
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Finding large devious primes
Call a prime $p$ devious if $(p-1)/2$ is a Carmichael number. They are called devious since they superficially look like safe primes but are not. In particular, Diffie-Hellman using such a prime could ...
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Constraints on q for q-ary lattices?
In lattice cryptography, people often work with q-ary lattices so that we can use the hardness of short integer solution (SIS) and learning with errors (LWE). I saw in some notes that sometimes we ...
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Inverse function of RSA and safe prime requirement of DH Key exchange
Ok so the inverse function of RSA encryption (that is decryption) is
$ m \gets c^{d}\bmod N$ where $d$ is the secret exponent
As I understand the hardness of RSA depends on two things: the Integer ...
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How to get the order of a group generator in DH?
For a DH parameter prime, if the generator $g$ is 2, how do I get the order $q$?