Key Agreement Protocol

Key exchange protocols enable two or more parties to establish a shared encryption key that they can use to encrypt or sign data that they plan to exchange. Key exchange protocols typically employ cryptography to achieve this goal. Different cryptographic techniques can be used to achieve this goal.

In order for two parties to communicate confidentially, they must first exchange the secret key that will be used to encrypt and decrypt messages. This initial exchange of the encryption key is called the key exchange.

Key exchange protocols are designed to solve the problem of confidentially establishing a secret key between two or more parties without letting an unauthorized party somehow intercept, infer or otherwise obtain the key.

A naive example of a key exchange protocol is for one party to write down a secret key, place it in a tamper-evident envelope and send it to the receiver. If the envelope is intact, then the secret key can be used by both parties to encrypt and decrypt messages.

Commonly used key-agreement protocols include Diffie-Hellman, or protocols that are based on RSA or ECC.

Frequently Asked Questions
What is Diffie Hellman key exchange algorithm?

Diffie Hellman (DH) key exchange algorithm is a method of securely exchanging cryptographic keys over a public communications channel. It is named after their inventors Whitfield Diffie and Martin Hellman.

What is the role of key agreement protocol in authentication?

A key agreement protocol is typically invoked after two parties have been authenticated. The agreement on a shared key allows the parties to securely communicate over untrusted communications networks.

Is Internet Key exchange (IKE) used in key agreement protocol?

Internet Key Exchange (IKE) is the protocol used to set up a secure, authenticated communications channel between two parties. IKE uses X.509 PKI certificates for authentication and the Diffie–Hellman key exchange protocol to set up a shared session secret.