// newManagedAddress returns a new managed address based on the passed account,
// private key, and whether or not the public key is compressed. The managed
// address will have access to the private and public keys.
func newManagedAddress(m *Manager, account uint32, privKey *btcec.PrivateKey,
compressed bool, addrType addressType) (*managedAddress, error) {
// Encrypt the private key.
//
// NOTE: The privKeyBytes here are set into the managed address which
// are cleared when locked, so they aren't cleared here.
privKeyBytes := privKey.Serialize()
privKeyEncrypted, err := m.cryptoKeyPriv.Encrypt(privKeyBytes)
if err != nil {
str := "failed to encrypt private key"
return nil, managerError(ErrCrypto, str, err)
}
// Leverage the code to create a managed address without a private key
// and then add the private key to it.
ecPubKey := (*btcec.PublicKey)(&privKey.PublicKey)
managedAddr, err := newManagedAddressWithoutPrivKey(m, account,
ecPubKey, compressed, addrType)
if err != nil {
return nil, err
}
managedAddr.privKeyEncrypted = privKeyEncrypted
managedAddr.privKeyCT = privKeyBytes
return managedAddr, nil
}
// deriveElkremRoot derives an elkrem root unique to a channel given the
// private key for our public key in the 2-of-2 multi-sig, and the remote
// node's multi-sig public key. The root is derived using the HKDF[1][2]
// instantiated with sha-256. The secret data used is our multi-sig private
// key, with the salt being the remote node's public key.
//
// [1]: https://eprint.iacr.org/2010/264.pdf
// [2]: https://tools.ietf.org/html/rfc5869
func deriveElkremRoot(elkremDerivationRoot *btcec.PrivateKey,
localMultiSigKey *btcec.PublicKey,
remoteMultiSigKey *btcec.PublicKey) wire.ShaHash {
secret := elkremDerivationRoot.Serialize()
salt := localMultiSigKey.SerializeCompressed()
info := remoteMultiSigKey.SerializeCompressed()
rootReader := hkdf.New(sha256.New, secret, salt, info)
// It's safe to ignore the error her as we know for sure that we won't
// be draining the HKDF past its available entropy horizon.
// TODO(roasbeef): revisit...
var elkremRoot wire.ShaHash
rootReader.Read(elkremRoot[:])
return elkremRoot
}
