The Diffie-Hellman (DH) algorithm is a foundational cryptographic protocol used for key exchange or key agreement. Its primary function is to allow two parties, with no prior shared secret, to jointly establish a shared secret key over an insecure communication channel. This generated key can then be used for a symmetric encryption algorithm (like AES) to secure subsequent communications. The DH protocol itself does not perform encryption, integrity checks, or provide non-repudiation; its sole purpose is the secure establishment of a shared secret.

A. Confidentiality: DH enables confidentiality by creating a key for symmetric ciphers, but it does not provide confidentiality directly.

C. Integrity: DH offers no mechanism to verify that data has not been altered. This is the function of hashing algorithms like SHA-256.

D. Non-repudiation: DH does not provide proof of origin. This is achieved with digital signature algorithms like RSA or ECDSA.

1. National Institute of Standards and Technology (NIST) Special Publication 800-56A Revision 3

Recommendation for Pair-wise Key-Establishment Schemes Using Discrete Logarithm Cryptography

April 2018.

Page 1

Section 1 (Introduction): "This Recommendation specifies key-establishment schemes... Such a scheme is called a Diffie-Hellman (DH) or Elliptic Curve Diffie-Hellman (ECDH) key-agreement scheme

and the process is called key agreement."

2. Internet Engineering Task Force (IETF) RFC 2631

Diffie-Hellman Key Agreement Method

June 1999.

Page 1

Section 1 (Introduction): "The Diffie-Hellman method allows two parties to agree upon a shared secret value in a manner that is secure against eavesdroppers. This value can then be converted into cryptographic keying material."

3. Rivest

R. L.

Shamir

A.

& Adleman

L. (1978). A method for obtaining digital signatures and public-key cryptosystems. Communications of the ACM

21(2)

120–126.

Page 124

Section VI (Public-Key Schemes): The paper

while introducing RSA

references the work of Diffie and Hellman

stating

"Diffie and Hellman have proposed a scheme... in which user A can send a message to user B so that only B can read it." It clarifies this is achieved by first establishing a key

describing the DH protocol as a "public-key distribution system." DOI: https://doi.org/10.1145/359340.359342

4. Katz

J.

& Lindell

Y. (2014). Introduction to Modern Cryptography (2nd ed.). CRC Press.

Page 356

Section 10.3 (The Diffie-Hellman Protocols): "The Diffie-Hellman key-exchange protocol is a method by which two parties can compute a shared key... The protocol is secure against an eavesdropper who observes the entire interaction."