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signrpc: use ECDH interface for shared key generation

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This commit is contained in:
Oliver Gugger 2020-04-28 10:06:32 +02:00
parent f97e7b9951
commit 4003f25281
No known key found for this signature in database
GPG Key ID: 8E4256593F177720
1 changed files with 6 additions and 23 deletions
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29
lnrpc/signrpc/signer_server.go
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@ -5,7 +5,6 @@ package signrpc
import (
"bytes"
"context"
"crypto/sha256"
"fmt"
"io/ioutil"
"os"
@ -515,31 +514,15 @@ func (s *Server) DeriveSharedKey(_ context.Context, in *SharedKeyRequest) (
locator.Index = uint32(in.KeyLoc.KeyIndex)
}
// Derive our node's private key from the key ring.
idPrivKey, err := s.cfg.KeyRing.DerivePrivKey(keychain.KeyDescriptor{
KeyLocator: locator,
})
// Derive the shared key using ECDH and hashing the serialized
// compressed shared point.
keyDescriptor := keychain.KeyDescriptor{KeyLocator: locator}
sharedKeyHash, err := s.cfg.KeyRing.ECDH(keyDescriptor, ephemeralPubkey)
if err != nil {
err := fmt.Errorf("unable to derive node private key: %v", err)
err := fmt.Errorf("unable to derive shared key: %v", err)
log.Error(err)
return nil, err
}
idPrivKey.Curve = btcec.S256()
// Derive the shared key using ECDH and hashing the serialized
// compressed shared point.
sharedKeyHash := ecdh(ephemeralPubkey, idPrivKey)
return &SharedKeyResponse{SharedKey: sharedKeyHash}, nil
}
// ecdh performs an ECDH operation between pub and priv. The returned value is
// the sha256 of the compressed shared point.
func ecdh(pub *btcec.PublicKey, priv *btcec.PrivateKey) []byte {
s := &btcec.PublicKey{}
x, y := btcec.S256().ScalarMult(pub.X, pub.Y, priv.D.Bytes())
s.X = x
s.Y = y
h := sha256.Sum256(s.SerializeCompressed())
return h[:]
return &SharedKeyResponse{SharedKey: sharedKeyHash[:]}, nil
}