What is a key derivation function in cryptography?
Q: What is a key derivation function in cryptography?
A: A key derivation function (KDF) is a function used in cryptography to generate a long secret key (also known as a “hash”) from a secret phrase, such as a password.
Q: How does a key derivation function generate a secret key?
A: A key derivation function generates a secret key by applying an algorithm to a secret phrase (e.g., a password) to produce a longer, fixed-length value that looks like a random string of bits.
Q: What does the output of a key derivation function look like?
A: The output of a key derivation function looks like a random string of bits and is designed to be the same for the same input phrase regardless of how many times the function is applied.
Q: What is the purpose of a key derivation function?
A: The purpose of a key derivation function is to produce a long, secure secret key that can be used to encrypt and decrypt data in a secure manner.
Q: Can a key derivation function be used to generate secret keys for different cryptographic algorithms?
A: Yes, a key derivation function can be used to generate secret keys for different cryptographic algorithms as long as they require the same key size and format.
Q: How are key derivation functions used to re-use secret keys in encryption?
A: Key derivation functions are used to re-use secret keys in encryption by generating a new secret key from a shared secret key produced by a key exchange algorithm (like the Diffie-Hellman key exchange) and then using the new key to encrypt and decrypt data using a specific encryption algorithm (like AES).
Q: What is the benefit of using a key derivation function in cryptography?
A: The benefit of using a key derivation function in cryptography is that it enables the creation of long, secure secret keys that can be used for encryption and decryption without having to manually generate and store individual keys for each use case.
