Diffie-Hellman Key Exchange

Online Diffie-Hellman key exchange tool with ECDH and X25519 negotiation, two-party public key exchange, and shared-secret verification for TLS demos, secure channel debugging, and cryptography learning.

How Diffie-Hellman Works

Alice and Bob generate key pairs, exchange public keys, and derive the same shared secret independently. Even if public keys are intercepted, the shared secret cannot be directly recovered.

Algorithm Settings

Key Exchange Algorithm

Derived Key Length (bytes)

Derived length controls the final shared-secret output size.

Alice

Private Key

(shown after key generation)

Public Key (send to peer)

(shown after key generation)

Peer Public Key

Bob

Private Key

(shown after key generation)

Public Key (send to peer)

(shown after key generation)

Peer Public Key

Quick Demo (Auto Mode)

Click the button below to run the full key exchange flow automatically.

Documentation

This tool demonstrates Diffie-Hellman (including ECDH) key exchange, showing how Alice and Bob derive the same shared secret over a public channel.

Key Features

Multiple DH/ECDH algorithm options
Per-party key generation and public key exchange
Shared-secret computation and consistency check
Built-in auto demo flow

Steps

Select algorithm and derived key length.
Generate key pairs for Alice and Bob.
Exchange public keys and fill peer key fields.
Compute both shared secrets and verify they match.

Use Cases

Key agreement education
ECDH interoperability testing
Security protocol onboarding demos

Notes

DH provides key agreement, not identity authentication.
Production systems should combine certificates or signatures to prevent MITM attacks.
Both parties must use the same algorithm parameters.