In the original description, the Diffie–Hellman exchange by itself does not provide authentication of the communicating parties and is thus vulnerable to a man-in-the-middle attack. ... A method to authenticate the communicating parties to each other is generally needed to prevent this type of attack.

Can Diffie-Hellman be used for authentication?

The Diffie-Hellman (DH) method of authenticating a user is nontrivial for an intruder to crack. Authentication is based on the ability of the sending system to use the common key to encrypt the current time, which the receiving system can decrypt and check against its current time. ...

What does Diffie-Hellman do?

The Diffie–Hellman (DH) Algorithm is a key-exchange protocol that enables two parties communicating over public channel to establish a mutual secret without it being transmitted over the Internet. DH enables the two to use a public key to encrypt and decrypt their conversation or data using symmetric cryptography.

What is authenticated Diffie-Hellman key agreement?

Authenticated Diffie-Hellman key agreement (D-H key) is the de facto building block for establishing secure session keys in many security systems. ... This new scheme is attractive to those applications where the clients need identity protection and lightweight computation.

Is Diffie-Hellman public key cryptography?

Both RSA and Diffie-Hellman are public-key encryption algorithms strong enough for commercial purposes because they are both based on supposedly intractable problems, the difficulty of factoring large numbers and exponentiation and modular arithmetic respectively.

Secret Key Exchange (Diffie-Hellman) - Computerphile

35 related questions found

How does Diffie-Hellman key exchange protocol 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.

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 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.

Why Diffie-Hellman is secure?

Ephemeral Diffie-Hellman – This is considered the most secure implementation because it provides perfect forward secrecy. ... This gives the connection perfect forward secrecy, because even if a key is compromised in the future, it can't be used to decrypt all of the past messages.

What is Diffie-Hellman group?

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.

Which computational problem does the security of DH rely on?

Relation to Decisional Diffie–Hellman Assumption

The semantic security of the Diffie-Hellman Key Exchange as well as the security of the ElGamal encryption rely on the hardness of the DDH problem.

What is the purpose of Diffie Hellman algorithm write down its steps?

The Diffie-Hellman algorithm is being used to establish a shared secret that can be used for secret communications while exchanging data over a public network using the elliptic curve to generate points and get the secret key using the parameters.

Are DH parameters secret?

The DH parameters created by "dhparam" don't contain any secrets; they're entirely public. The secrets used in Diffie-Hellman are chosen by the participants in the key exchange at the moment that it's used.

Is Diffie-Hellman symmetric or asymmetric?

DH is not a symmetric algorithm – it is an asymmetric algorithm used to establish a shared secret for a symmetric key algorithm.

Why does Diffie-Hellman use prime numbers?

1 Answer. Prime numbers don't break down into smaller factors, making cracking the code or hash much harder than using, say 12, which breaks down with /2 or /3 or /4 or /6. The prime number 7, is less than 12, but only has the factor of 7, so there are less attack vectors.

When using Diffie Hellman key exchange what is the one of the benefits?

Advantages of the Diffie Hellman Algorithm

The sender and receiver don't need any prior knowledge of each other. Once the keys are exchanged, the communication of data can be done through an insecure channel. The sharing of the secret key is safe.

What are the applications of the DH algorithm?

Applications of Diffie Hellman Algorithm:

Transport Layer Security (TLS) / Secure Sockets Layer (SSL) Public Key Infrastructure (PKI) Internet Key Exchange (IKE) Internet Protocol Security (IPSec)

Which key exchange technique is not supported by SSLv3?

Which key exchange technique is not supported by SSLv3? Explanation: Fortezza is not supported in SSLv3.

What does a message authentication code provide?

Message authentication codes (MACs) are commonly used in electronic funds transfers (EFTs) to maintain information integrity. They confirm that a message is authentic; that it really does come, in other words, from the stated sender, and hasn't undergone any changes en route.

What is elliptic curve cryptography used for?

Elliptic curve cryptography is now used in a variety of applications: the U.S. government uses it to protect internal communications, the Tor project uses it to help assure anonymity, it is the mechanism used to prove ownership of bitcoins, it provides signatures in Apple's iMessage service, it is used to encrypt DNS ...

What is computational Diffie-Hellman problem?

The computational Diffie–Hellman (CDH assumption) is the assumption that a certain computational problem within a cyclic group is hard. The security of many cryptosystems is based on the CDH assumption, including notably the Diffie–Hellman key agreement scheme.

What is computational and decisional Diffie-Hellman problem?

The decisional Diffie–Hellman (DDH) assumption is a computational hardness assumption about a certain problem involving discrete logarithms in cyclic groups. It is used as the basis to prove the security of many cryptographic protocols, most notably the ElGamal and Cramer–Shoup cryptosystems.

What is the significance of the Diffie-Hellman setting in IPsec VPNS?

Diffie-Hellman (DH) is a public-key cryptography scheme that allows two parties to establish a shared secret over an insecure communications channel. IKE uses DH to create keys used to encrypt both the Internet Key Exchange (IKE) and IPsec communication channels.

What is Diffie-Hellman Group Exchange sha256?

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. It is a reasonably simple transition to move from SHA-1 to SHA-2.