## Who is Whitfield Diffie and Martin Hellman?

Whitfield Diffie is a former Vice President and Chief Security Officer of Sun Microsystems, where he became a Sun Fellow. Martin E. Hellman is Professor Emeritus of Electrical Engineering at Stanford University, where he was Professor of Electrical Engineering for 25 years.

**What did Whitfield Diffie do?**

Whitfield Diffie is a consulting scholar at CISAC. He was a visiting scholar in 2009-2010 and an affiliate from 2010-2012. He is best known for the discovery of the concept of public key cryptography, in 1975, which he developed along with Stanford University Electrical Engineering Professor Martin Hellman.

**Which fundamental cryptographic problem did Whitfield Diffie address in his 1976 mathematics paper?**

key distribution

Diffie and Hellman’s 1976 paper New Directions in Cryptography introduced a radically new method of distributing cryptographic keys, that helped solve key distribution—a fundamental problem in cryptography. Their technique became known as Diffie–Hellman key exchange.

### What are Diffie-Hellman groups?

Diffie-Hellman (DH) groups determine the strength of the key used in the key exchange process. Within a group type (MODP or ECP), higher Diffie-Hellman group numbers are usually more secure. Diffie-Hellman performance can vary by WatchGuard hardware model.

**What did Whitfield Diffie invent?**

public key cryptography

In 1976, Whitfield Diffie, Martin Hellman, and Ralph Merkle developed public key cryptography (PKC), an innovative new method for securing electronic communications. PKC provides security on the otherwise highly insecure Internet, making it vital to such areas as e-commerce.

**What are Diffie-Hellman parameters?**

The Diffie-Hellman key agreement parameters are the prime P, the base G, and, in non-FIPS mode, the optional subprime Q, and subgroup factor J. Diffie-Hellman key pairs are the private value X and the public value Y.

#### How do you decrypt Diffie-Hellman?

Encrypt and decrypt a number

- Select the shared numbers. select a large prime number P.
- Select the private key and share the public key. Let’s look at two users, Alice and Bob.
- Compute the super key for encoding and decoding. Alice computes her super key as X = B^a mod P.
- Use the superkey to encrypt and decrypt.

**What is the best Diffie-Hellman group?**

If you are using encryption or authentication algorithms with a 128-bit key, use Diffie-Hellman groups 19, 20. If you are using encryption or authentication algorithms with a 256-bit key or higher, use Diffie-Hellman group 21.

**What is Diffie-Hellman Group 14?**

diffie-hellman-group14-sha256. This key exchange uses the group14 (a 2048-bit MODP group) along with a SHA-2 (SHA2-256) hash. This represents the smallest Finite Field Cryptography (FFC) Diffie-Hellman (DH) key exchange method considered to be secure.

## How do I check my Diffie-Hellman?

One way to see if a server or endpoint supports Diffie-Hellman is to use the nmap tool with the option for the ssl-enum-ciphers script, as shown in the example below, to list all supported cipher suites. All cipher suites that list DH, DHE, or ECDHE use Diffie-Hellman.

**What kind of keys will be exchanged between two parts in Diffie Hellman?**

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.