Allow selection of address on sign path (#6)

internal/usecase/path_sign.go

@@ -2,6 +2,7 @@ package usecase
 
 import (
 	"context"
+	"errors"
 	"fmt"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -32,6 +33,10 @@ func pathSign(b *Backend) *framework.Path {
 				Description: "Hex string of the hash that should be signed.",
 				Default:     "",
 			},
+			"address": {
+				Type:        framework.TypeString,
+				Description: "The address that belongs to a private key in the key-manager.",
+			},
 		},
 	}
 }
@@ -51,6 +56,11 @@ func (b *Backend) sign(
 		return nil, errInvalidType
 	}
 
+	address, ok := data.Get("address").(string)
+	if !ok {
+		return nil, errInvalidType
+	}
+
 	keyManager, err := b.retrieveKeyManager(ctx, req, serviceNameInput)
 	if err != nil {
 		b.Logger().Error("Failed to retrieve the signing keyManager",
@@ -66,7 +76,19 @@ func (b *Backend) sign(
 		return nil, fmt.Errorf("signing keyManager %s does not have a key pair", serviceNameInput)
 	}
 
-	privateKey, err := crypto.HexToECDSA(keyManager.KeyPairs[0].PrivateKey)
+	var privateKeyStr string
+	for _, keyPairs := range keyManager.KeyPairs {
+		if keyPairs.Address == address {
+			privateKeyStr = keyPairs.PrivateKey
+			break
+		}
+	}
+
+	if privateKeyStr == "" {
+		return nil, errors.New("no private key for the input address")
+	}
+
+	privateKey, err := crypto.HexToECDSA(privateKeyStr)
 	if err != nil {
 		b.Logger().Error("Error reconstructing private key from retrieved hex", "error", err)
 		return nil, fmt.Errorf("error reconstructing private key from retrieved hex")

internal/usecase/path_sign_test.go

@@ -14,16 +14,22 @@ func TestBackend_sign(t *testing.T) {
 	b, _ := newTestBackend(t)
 
 	const (
-		testSvc = "test-service"
+		testSvc          = "test-service"
+		privateKeyString = "3ee65159f7aa057c482b1041f18f37ce90ef5e460cb46fd3fa0c40fbae41c7e1"
 	)
+	privateKey, err := crypto.HexToECDSA(privateKeyString)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	address := crypto.PubkeyToAddress(privateKey.PublicKey)
 
 	req := logical.TestRequest(t, logical.UpdateOperation, "key-managers")
 	storage := req.Storage
 	req.Data = map[string]interface{}{
 		"serviceName": testSvc,
-		"privateKey":  "3ee65159f7aa057c482b1041f18f37ce90ef5e460cb46fd3fa0c40fbae41c7e1",
+		"privateKey":  privateKeyString,
 	}
-	_, err := b.HandleRequest(context.Background(), req)
+	_, err = b.HandleRequest(context.Background(), req)
 	if err != nil {
 		t.Fatalf("err: %v", err)
 	}
@@ -34,7 +40,8 @@ func TestBackend_sign(t *testing.T) {
 	req = logical.TestRequest(t, logical.CreateOperation, "key-managers/"+testSvc+"/sign")
 	req.Storage = storage
 	data := map[string]interface{}{
-		"hash": hash.Hex(),
+		"hash":    hash.Hex(),
+		"address": address.String(),
 	}
 	req.Data = data
 	resp, err := b.HandleRequest(context.Background(), req)