// SealAfterPrecomputation performs the same actions as Seal, but takes a
// shared key as generated by Precompute.
func SealAfterPrecomputation(out, message []byte, nonce *[24]byte, sharedKey *[32]byte) []byte {
return secretbox.Seal(out, message, nonce, sharedKey)
}
// Seal appends an encrypted and authenticated copy of message to out, which
// will be Overhead bytes longer than the original and must not overlap. The
// nonce must be unique for each distinct message for a given pair of keys.
func Seal(out, message []byte, nonce *[24]byte, peersPublicKey, privateKey *[32]byte) []byte {
var sharedKey [32]byte
Precompute(&sharedKey, peersPublicKey, privateKey)
return secretbox.Seal(out, message, nonce, &sharedKey)
}