support lighter spot

docs/lighter/lighter-go-main/signer/key_manager.go

@@ -0,0 +1,54 @@
+package signer
+
+import (
+	"fmt"
+	"hash"
+
+	curve "github.com/elliottech/poseidon_crypto/curve/ecgfp5"
+	gFp5 "github.com/elliottech/poseidon_crypto/field/goldilocks_quintic_extension"
+	schnorr "github.com/elliottech/poseidon_crypto/signature/schnorr"
+)
+
+type Signer interface {
+	Sign(message []byte, hFunc hash.Hash) ([]byte, error)
+}
+
+type KeyManager interface {
+	Signer
+	PubKey() gFp5.Element
+	PubKeyBytes() [40]byte
+	PrvKeyBytes() []byte
+}
+
+type keyManager struct {
+	key curve.ECgFp5Scalar
+}
+
+func NewKeyManager(b []byte) (KeyManager, error) {
+	if len(b) != 40 {
+		return nil, fmt.Errorf("invalid private key length. expected: 40 got: %v", len(b))
+	}
+	return &keyManager{key: curve.ScalarElementFromLittleEndianBytes(b)}, nil
+}
+
+func (key *keyManager) Sign(hashedMessage []byte, hFunc hash.Hash) ([]byte, error) {
+	hashedMessageAsQuinticExtension, err := gFp5.FromCanonicalLittleEndianBytes(hashedMessage)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse message while signing. message: %v err: %w", hashedMessage, err)
+	}
+	return schnorr.SchnorrSignHashedMessage(hashedMessageAsQuinticExtension, key.key).ToBytes(), nil
+}
+
+func (key *keyManager) PubKey() gFp5.Element {
+	return schnorr.SchnorrPkFromSk(key.key)
+}
+
+func (key *keyManager) PubKeyBytes() (res [40]byte) {
+	bytes := key.PubKey().ToLittleEndianBytes()
+	copy(res[:], bytes[:])
+	return
+}
+
+func (key *keyManager) PrvKeyBytes() []byte {
+	return key.key.ToLittleEndianBytes()
+}