The Diffie-Hellman key exchange is a fundamental cryptographic protocol that allows two parties to establish a shared secret over an insecure channel. This interactive tool demonstrates how the algorithm works with real-time security analysis and educational resources.
Public Parameters
Participant Keys
Alice
Private: 6
Public: Not calculated
⇄
Bob
Private: 15
Public: Not calculated
Shared Secret Key
Shared Secret: Not calculated yet
Hex: -
Binary: -
Security Analysis
Key Strength
Weak
Prime Security
Low
Exchange Security
Moderate
Security analysis will appear here after key calculation.
Exchange History
How Diffie-Hellman Works
1Agree on Public Parameters: Alice and Bob agree on a large prime number (p) and a base (g).
2Generate Private Keys: Each selects a private key (a for Alice, b for Bob) that they keep secret.
3Calculate Public Keys: Alice computes A = ga mod p, Bob computes B = gb mod p.
4Exchange Public Keys: Alice sends A to Bob, Bob sends B to Alice.
5Compute Shared Secret: Alice computes s = Ba mod p, Bob computes s = Ab mod p.
6Use Shared Key: Both now have the same shared secret s, which can be used as a symmetric encryption key.
Frequently Asked Questions
What is the Diffie-Hellman key exchange?
The Diffie-Hellman key exchange is a cryptographic protocol that allows two parties to establish a shared secret key over an insecure communication channel. It was one of the first practical implementations of public-key cryptography and is widely used in secure communications protocols.
Is Diffie-Hellman secure against eavesdroppers?
Yes, when implemented correctly with sufficiently large parameters, Diffie-Hellman is secure against passive eavesdroppers. However, it is vulnerable to man-in-the-middle attacks unless additional authentication measures are implemented.
What key sizes are considered secure today?
For modern security, 2048-bit primes are considered the minimum for Diffie-Hellman, with 3072-bit or 4096-bit primes recommended for long-term security. The private keys should be at least 224 bits for 2048-bit primes.
Where is Diffie-Hellman used in practice?
Diffie-Hellman is used in many security protocols including TLS/SSL (for secure web browsing), SSH (secure shell), IPsec (VPNs), and various encrypted messaging applications. It's often used as part of a key exchange mechanism rather than alone.
What's the difference between Diffie-Hellman and RSA?
While both are public-key cryptosystems, Diffie-Hellman is primarily used for key exchange, allowing two parties to establish a shared secret. RSA can be used for both key exchange and digital signatures. The mathematical problems they're based on are different: discrete logarithm for DH and integer factorization for RSA.