pub fn box_open(
    nonce: &[u8; 15],
    ciphertext: Vec<u8>,
    additional_data: Vec<u8>,
    peers_public_key: &PublicKey,
    private_key: &StaticSecret,
) -> Result<Vec<u8>>Expand description
Unboxes (“opens”) the provided additional data and ciphertext via
Deoxys-II-256-128 using a symmetric key derived from the provided
X25519 public and private keys.
The nonce should be NONCE_SIZE bytes long and both it and the additional
data must match the value passed to box_seal.