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SEC

Software → Security

Diffie-Hellman Key Exchange

A key exchange method that lets two parties establish a shared secret over an insecure channel.

Motivation

Diffie-Hellman solves the problem of deriving a shared secret across an open channel.

Where it fits

Diffie-Hellman belongs to key exchange and public-key cryptography.

Mental model

Two parties exchange public values and independently compute the same shared secret without sending it directly.

Common mistakes

  • Using unauthenticated Diffie-Hellman against active attackers.
  • Confusing it with encryption of messages.

Diffie-Hellman connects to key exchange, TLS, and public-key cryptography.