pub mod key_derivation {
use crate::crypto::cipher_suite::CipherSuiteParams;
pub fn expand_subsecret(cipher_suite: &CipherSuiteParams, key: &[u8]) -> (Vec<u8>, Vec<u8>) {
let aes_keysize = key.len() - cipher_suite.hash_len;
let enc_key = key[..aes_keysize].to_vec();
let auth_key = key[aes_keysize..].to_vec();
(enc_key, auth_key)
}
}