Function solana_libra_crypto::x25519::derive_keypair_from_seed

pub fn derive_keypair_from_seed(
    salt: Option<&[u8]>, 
    seed: &[u8], 
    app_info: Option<&[u8]>
) -> (X25519PrivateKey, X25519PublicKey)

Derives a keypair (X25519PrivateKey, X25519PublicKey) from a) salt (optional) - denoted as 'salt' in RFC 5869 b) seed - denoted as 'IKM' in RFC 5869 c) application info (optional) - denoted as 'info' in RFC 5869

using the HKDF key derivation protocol, as defined in RFC 5869. This implementation uses the full extract-then-expand HKDF steps based on the SHA-256 hash function.

Warning: This function will soon be updated to return a KeyPair struct.