Key Derivation Functions can be used to stretch keys into longer Cryptographic Key or to obtain Cryptographic Keys of a required format, such as converting a group element that is the result of a Diffie-Hellman key-exchange into a Symmetric Key for use with AES. Keyed-Hash Message Authentication Codes are popular examples of pseudorandom number generator functions used for Key Derivation Function.
More Information#There might be more information for this subject on one of the following:
- Double Ratchet Algorithm
- Key Generation
- Password-Based Key Derivation Function
- Shared Secret
- TLS 1.3