Diffie-Hellman Key Exchange

cryptography

Definition

Diffie-Hellman Key Exchange

The Diffie-Hellman key exchange is a key exchange algorithm for two parties to agree on a shared secret key over an insecure channel. Its security relies on the hardness of the discrete logarithm problem.

Protocol

Let be a prime and a primitive root modulo , agreed upon publicly.

1. Alice chooses a secret and sends to Bob

2. Bob chooses a secret and sends to Alice

3. Alice computes the shared secret

4. Bob computes the shared secret

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Man-in-the-Middle Attack

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Footnotes

1. 192.019 Introduction to Security ↩ ↩²