# What is pohlig Hellman attack?

## What is pohlig Hellman attack?

The Pohlig-Hellman attack simplifies the problem of solving the ECDLP in E(Fp) to solving the ECDLP in the prime subgroups of ⟨P⟩, the subgroup generated by P. Let n be the order of E(Fp). We want to find ki≡kmodpeii for each prime and solve the k using the Chinese Remainder Theorem.

## How does Diffie Hellman key exchange work?

In the Diffie–Hellman key exchange scheme, each party generates a public/private key pair and distributes the public key. After obtaining an authentic copy of each other’s public keys, Alice and Bob can compute a shared secret offline. The shared secret can be used, for instance, as the key for a symmetric cipher.

What is discrete logarithm in cryptography?

Discrete logarithms are logarithms defined with regard to multiplicative cyclic groups. If G is a multiplicative cyclic group and g is a generator of G, then from the definition of cyclic groups, we know every element h in G can be written as gx for some x.

How do you find the discrete log?

Finding a discrete logarithm can be very easy. For example, say G = Z/mZ and g = 1. More specifically, say m = 100 and t = 17. Then logg t = 17 (or more precisely 17 mod 100).

### What is discrete log parameter?

An integer k that solves the equation bk = a is termed a discrete logarithm (or simply logarithm, in this context) of a to the base b. One writes k = logb a.

### What is the discrete log problem in Diffie Hellman algorithm?

The discrete logarithm problem is the basis for the following cryptographic algorithms: Diffie- Hellman key exchange, ElGamal encryption, and the Digital Signature Algorithm. Notice that breaking Diffie-Hellman key exchange might not be equivalent to solving the discrete logarithm problem.

Why is discrete logarithm problem hard?

For the discrete algorithm problem, you normally would not write the whole group (or even its multiplication table of size n2) as the input, but only some key parameters which allow calculating the group law, as well as the element of which you want to get the logarithm.

Are logarithms discrete or continuous?

Therefore, logarithms are part of discrete and continuous mathematics as they help in modeling different situations of discrete and continuous mathematical problems. Logarithms are not just a tool for finding the logarithmic function; they are used in many different contexts to model and solve problems in mathematics.

## How do you break a Diffie-Hellman?

To attack a Diffie-Hellman key exchange, one could extract the secret key a from one of the peer’s public key ya = ga (mod p). One could then compute the shared key gab (mod p) using the other peer’s public key yb = gb (mod p).

Where is Diffie-Hellman used?

The Diffie-Hellman algorithm will be used to establish a secure communication channel. This channel is used by the systems to exchange a private key. This private key is then used to do symmetric encryption between the two systems.

What is the difference between RSA and Diffie-Hellman?

The asymmetric key includes many cryptographic algorithms. Both Diffie- Hellman Key Exchange and RSA have advantages and disadvantages….Diffie- Hellman Key Exchange Vs. RSA.

Parameters RSA Diffie-Hellman (DH) Key Exchange
Key Strength RSA 1024 bits is less robust than Diffie-Hellman. Diffie-Hellman 1024 bits is much more robust.

### What is the Pohlig-Hellman algorithm?

The Pohlig-Hellman Algorithm helps solve the Discrete Log Problem for Finite Fields whose order can be factored into prime powers of smaller primes. The algorithm reduces the computation of the discrete log in the Finite Field G to the computation of the discrete log in prime order subgroups of ⟨G⟩

### What is Pohlig Hellman in Python?

GitHub – christiankrug/pohlig_hellman: Python implementation of the Pohlig Hellman algorithm, used to solve the discrete logarithm problem in cyclic groups, especially in those where the group order is factored from small prime numbers. Use Git or checkout with SVN using the web URL. Work fast with our official CLI. Learn more .

How do you solve X in Pohlig Hellman’s equation?

When solving for x in the equation g x ≡ h mod p the idea behind Pohlig Hellman is to solve discrete logs on group elements with smaller orders and then recombine those results to obtain x. For each prime factor q e of p − 1 you do the following: Find an element with order q e. You can do this via g ′ = g n q e mod p. Compute h ′ = h n q e mod p.

Which theorem is similar to the Pohlig-Hellman theorem?

Pohlig-Hellman is also similarly applicable for the Discrete Log Problem in ECC. Groups are additive groups & not Multiplicative Groups. We used Fermat’s Little Theorem for solving multiplicative Group DLP. Fermat’s Little Theorem is a special case of Lagrange’s Theorem.