83 lines
2.6 KiB
Go
83 lines
2.6 KiB
Go
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package keychain
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import (
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"crypto/sha256"
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"github.com/btcsuite/btcd/btcec"
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)
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// NewPubKeyECDH wraps the given key of the key ring so it adheres to the
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// SingleKeyECDH interface.
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func NewPubKeyECDH(keyDesc KeyDescriptor, ecdh ECDHRing) *PubKeyECDH {
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return &PubKeyECDH{
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keyDesc: keyDesc,
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ecdh: ecdh,
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}
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}
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// PubKeyECDH is an implementation of the SingleKeyECDH interface. It wraps an
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// ECDH key ring so it can perform ECDH shared key generation against a single
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// abstracted away private key.
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type PubKeyECDH struct {
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keyDesc KeyDescriptor
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ecdh ECDHRing
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}
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// PubKey returns the public key of the private key that is abstracted away by
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// the interface.
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//
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// NOTE: This is part of the SingleKeyECDH interface.
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func (p *PubKeyECDH) PubKey() *btcec.PublicKey {
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return p.keyDesc.PubKey
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}
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// ECDH performs a scalar multiplication (ECDH-like operation) between the
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// abstracted private key and a remote public key. The output returned will be
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// the sha256 of the resulting shared point serialized in compressed format. If
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// k is our private key, and P is the public key, we perform the following
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// operation:
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//
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// sx := k*P
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// s := sha256(sx.SerializeCompressed())
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//
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// NOTE: This is part of the SingleKeyECDH interface.
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func (p *PubKeyECDH) ECDH(pubKey *btcec.PublicKey) ([32]byte, error) {
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return p.ecdh.ECDH(p.keyDesc, pubKey)
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}
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// PrivKeyECDH is an implementation of the SingleKeyECDH in which we do have the
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// full private key. This can be used to wrap a temporary key to conform to the
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// SingleKeyECDH interface.
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type PrivKeyECDH struct {
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// PrivKey is the private key that is used for the ECDH operation.
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PrivKey *btcec.PrivateKey
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}
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// PubKey returns the public key of the private key that is abstracted away by
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// the interface.
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//
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// NOTE: This is part of the SingleKeyECDH interface.
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func (p *PrivKeyECDH) PubKey() *btcec.PublicKey {
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return p.PrivKey.PubKey()
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}
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// ECDH performs a scalar multiplication (ECDH-like operation) between the
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// abstracted private key and a remote public key. The output returned will be
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// the sha256 of the resulting shared point serialized in compressed format. If
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// k is our private key, and P is the public key, we perform the following
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// operation:
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//
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// sx := k*P
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// s := sha256(sx.SerializeCompressed())
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//
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// NOTE: This is part of the SingleKeyECDH interface.
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func (p *PrivKeyECDH) ECDH(pub *btcec.PublicKey) ([32]byte, error) {
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s := &btcec.PublicKey{}
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s.X, s.Y = btcec.S256().ScalarMult(pub.X, pub.Y, p.PrivKey.D.Bytes())
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return sha256.Sum256(s.SerializeCompressed()), nil
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}
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var _ SingleKeyECDH = (*PubKeyECDH)(nil)
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var _ SingleKeyECDH = (*PrivKeyECDH)(nil)
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