feat(SPV-679): directed secret (#222)

contacts.go

@@ -30,8 +30,8 @@ func (b *WalletClient) RejectContact(ctx context.Context, paymail string) transp
 }
 
 // ConfirmContact will try to confirm the contact
-func (b *WalletClient) ConfirmContact(ctx context.Context, contact *models.Contact, passcode string, period, digits uint) transports.ResponseError {
-	isTotpValid, err := b.ValidateTotpForContact(contact, passcode, period, digits)
+func (b *WalletClient) ConfirmContact(ctx context.Context, contact *models.Contact, passcode, requesterPaymail string, period, digits uint) transports.ResponseError {
+	isTotpValid, err := b.ValidateTotpForContact(contact, passcode, requesterPaymail, period, digits)
 	if err != nil {
 		return transports.WrapError(fmt.Errorf("totp validation failed: %w", err))
 	}

contacts_test.go

@@ -2,10 +2,10 @@ package walletclient
 
 import (
 	"context"
+	"strings"
 	"testing"
 
 	"github.com/bitcoin-sv/spv-wallet-go-client/fixtures"
-	"github.com/bitcoin-sv/spv-wallet/models"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -57,17 +57,6 @@ func TestContactActionsRouting(t *testing.T) {
 				return err
 			},
 		},
-		{
-			name:            "ConfirmContact",
-			route:           "/contact/confirmed/",
-			responsePayload: "{}",
-			f: func(c *WalletClient) error {
-				contact := models.Contact{PubKey: fixtures.PubKey}
-
-				passcode, _ := c.GenerateTotpForContact(&contact, 30, 2)
-				return c.ConfirmContact(context.Background(), &contact, passcode, 30, 2)
-			},
-		},
 	}
 
 	for _, tc := range tcs {
@@ -104,14 +93,18 @@ func TestConfirmContact(t *testing.T) {
 			Client:    WithHTTPClient,
 		}
 
-		client := getTestWalletClientWithOpts(tmq, WithXPriv(fixtures.XPrivString))
+		clientMaker := func(opts ...ClientOps) (*WalletClient, error) {
+			return getTestWalletClientWithOpts(tmq, opts...), nil
+		}
+
+		alice := makeMockUser("alice", clientMaker)
+		bob := makeMockUser("bob", clientMaker)
 
-		contact := &models.Contact{PubKey: fixtures.PubKey}
-		totp, err := client.GenerateTotpForContact(contact, 30, 2)
+		totp, err := alice.client.GenerateTotpForContact(bob.contact, 30, 2)
 		require.NoError(t, err)
 
 		// when
-		result := client.ConfirmContact(context.Background(), contact, totp, 30, 2)
+		result := bob.client.ConfirmContact(context.Background(), alice.contact, totp, bob.paymail, 30, 2)
 
 		// then
 		require.Nil(t, result)
@@ -127,19 +120,40 @@ func TestConfirmContact(t *testing.T) {
 			Client:    WithHTTPClient,
 		}
 
-		client := getTestWalletClientWithOpts(tmq, WithXPriv(fixtures.XPrivString))
+		clientMaker := func(opts ...ClientOps) (*WalletClient, error) {
+			return getTestWalletClientWithOpts(tmq, opts...), nil
+		}
+
+		alice := makeMockUser("alice", clientMaker)
+		bob := makeMockUser("bob", clientMaker)
 
-		alice := &models.Contact{PubKey: "034252e5359a1de3b8ec08e6c29b80594e88fb47e6ae9ce65ee5a94f0d371d2cde"}
-		a_totp, err := client.GenerateTotpForContact(alice, 30, 2)
+		totp, err := alice.client.GenerateTotpForContact(bob.contact, 30, 2)
 		require.NoError(t, err)
 
-		bob := &models.Contact{PubKey: "02dde493752f7bc89822ed8a13e0e4aa04550c6c4430800e4be1e5e5c2556cf65b"}
+		//make sure the wrongTotp is not the same as the generated one
+		wrongTotp := incrementDigits(totp) //the length should remain the same
 
 		// when
-		result := client.ConfirmContact(context.Background(), bob, a_totp, 30, 2)
+		result := bob.client.ConfirmContact(context.Background(), alice.contact, wrongTotp, bob.paymail, 30, 2)
 
 		// then
 		require.NotNil(t, result)
 		require.Equal(t, result.Error(), "totp is invalid")
 	})
 }
+
+// incrementDigits takes a string of digits and increments each digit by 1.
+// Digits wrap around such that '9' becomes '0'.
+func incrementDigits(input string) string {
+	var result strings.Builder
+
+	for _, c := range input {
+		if c == '9' {
+			result.WriteRune('0')
+		} else {
+			result.WriteRune(c + 1)
+		}
+	}
+
+	return result.String()
+}

totp.go

@@ -19,42 +19,51 @@ import (
 var ErrClientInitNoXpriv = errors.New("init client with xPriv first")
 
 const (
-	// Default number of seconds a TOTP is valid for.
+	// TotpDefaultPeriod - Default number of seconds a TOTP is valid for.
 	TotpDefaultPeriod uint = 30
-	// Default TOTP length
+	// TotpDefaultDigits - Default TOTP length
 	TotpDefaultDigits uint = 2
 )
 
+/*
+Basic flow:
+Alice generates passcodeForBob with (sharedSecret+(contact.Paymail as bobPaymail))
+Alice sends passcodeForBob to Bob (e.g. via email)
+Bob validates passcodeForBob with (sharedSecret+(requesterPaymail as bobPaymail))
+The (sharedSecret+paymail) is a "directedSecret". This ensures that passcodeForBob-from-Alice != passcodeForAlice-from-Bob.
+The flow looks the same for Bob generating passcodeForAlice.
+*/
+
 // GenerateTotpForContact creates one time-based one-time password based on secret shared between the user and the contact
 func (b *WalletClient) GenerateTotpForContact(contact *models.Contact, period, digits uint) (string, error) {
-	secret, err := sharedSecret(b, contact)
+	sharedSecret, err := makeSharedSecret(b, contact)
 	if err != nil {
 		return "", err
 	}
 
 	opts := getTotpOpts(period, digits)
-	return totp.GenerateCodeCustom(string(secret), time.Now(), *opts)
+	return totp.GenerateCodeCustom(directedSecret(sharedSecret, contact.Paymail), time.Now(), *opts)
 }
 
 // ValidateTotpForContact validates one time-based one-time password based on secret shared between the user and the contact
-func (b *WalletClient) ValidateTotpForContact(contact *models.Contact, passcode string, period, digits uint) (bool, error) {
-	secret, err := sharedSecret(b, contact)
+func (b *WalletClient) ValidateTotpForContact(contact *models.Contact, passcode, requesterPaymail string, period, digits uint) (bool, error) {
+	sharedSecret, err := makeSharedSecret(b, contact)
 	if err != nil {
 		return false, err
 	}
 
 	opts := getTotpOpts(period, digits)
-	return totp.ValidateCustom(passcode, string(secret), time.Now(), *opts)
+	return totp.ValidateCustom(passcode, directedSecret(sharedSecret, requesterPaymail), time.Now(), *opts)
 }
 
-func sharedSecret(b *WalletClient, c *models.Contact) (string, error) {
+func makeSharedSecret(b *WalletClient, c *models.Contact) ([]byte, error) {
 	privKey, pubKey, err := getSharedSecretFactors(b, c)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
 	x, _ := bec.S256().ScalarMult(pubKey.X, pubKey.Y, privKey.D.Bytes())
-	return base32.StdEncoding.EncodeToString(x.Bytes()), nil
+	return x.Bytes(), nil
 }
 
 func getTotpOpts(period, digits uint) *totp.ValidateOpts {
@@ -115,3 +124,8 @@ func convertPubKey(pubKey string) (*bec.PublicKey, error) {
 
 	return bec.ParsePubKey(hex, bec.S256())
 }
+
+// directedSecret appends a paymail to the secret and encodes it into base32 string
+func directedSecret(sharedSecret []byte, paymail string) string {
+	return base32.StdEncoding.EncodeToString(append(sharedSecret, []byte(paymail)...))
+}

totp_test.go

@@ -1,10 +1,13 @@
 package walletclient
 
 import (
+	"encoding/hex"
 	"testing"
 
 	"github.com/bitcoin-sv/spv-wallet-go-client/fixtures"
+	"github.com/bitcoin-sv/spv-wallet-go-client/xpriv"
 	"github.com/bitcoin-sv/spv-wallet/models"
+	"github.com/libsv/go-bk/bip32"
 	"github.com/stretchr/testify/require"
 )
 
@@ -55,15 +58,18 @@ func TestGenerateTotpForContact(t *testing.T) {
 func TestValidateTotpForContact(t *testing.T) {
 	t.Run("success", func(t *testing.T) {
 		// given
-		sut, err := New(WithXPriv(fixtures.XPrivString), WithHTTP("localhost:3001"))
-		require.NoError(t, err)
-
-		contact := models.Contact{PubKey: fixtures.PubKey}
-		pass, err := sut.GenerateTotpForContact(&contact, 30, 2)
+		clientMaker := func(opts ...ClientOps) (*WalletClient, error) {
+			allOptions := append(opts, WithHTTP("localhost:3001"))
+			return New(allOptions...)
+		}
+		alice := makeMockUser("alice", clientMaker)
+		bob := makeMockUser("bob", clientMaker)
+
+		pass, err := alice.client.GenerateTotpForContact(bob.contact, 3600, 2)
 		require.NoError(t, err)
 
 		// when
-		result, err := sut.ValidateTotpForContact(&contact, pass, 30, 2)
+		result, err := bob.client.ValidateTotpForContact(alice.contact, pass, bob.paymail, 3600, 2)
 
 		// then
 		require.NoError(t, err)
@@ -76,7 +82,7 @@ func TestValidateTotpForContact(t *testing.T) {
 		require.NoError(t, err)
 
 		// when
-		_, err = sut.ValidateTotpForContact(nil, "", 30, 2)
+		_, err = sut.ValidateTotpForContact(nil, "", fixtures.PaymailAddress, 30, 2)
 
 		// then
 		require.ErrorIs(t, err, ErrClientInitNoXpriv)
@@ -90,10 +96,48 @@ func TestValidateTotpForContact(t *testing.T) {
 		contact := models.Contact{PubKey: "invalid-pk-format"}
 
 		// when
-		_, err = sut.ValidateTotpForContact(&contact, "", 30, 2)
+		_, err = sut.ValidateTotpForContact(&contact, "", fixtures.PaymailAddress, 30, 2)
 
 		// then
 		require.ErrorContains(t, err, "contact's PubKey is invalid:")
 
 	})
 }
+
+type mockUser struct {
+	contact *models.Contact
+	client  *WalletClient
+	paymail string
+}
+
+func makeMockUser(name string, clientMaker func(opts ...ClientOps) (*WalletClient, error)) mockUser {
+	keys, _ := xpriv.Generate()
+	paymail := name + "@example.com"
+	client, _ := clientMaker(WithXPriv(keys.XPriv()))
+	pki := makeMockPKI(keys.XPub().String())
+	contact := models.Contact{PubKey: pki, Paymail: paymail}
+	return mockUser{
+		contact: &contact,
+		client:  client,
+		paymail: paymail,
+	}
+}
+
+func makeMockPKI(xpub string) string {
+	xPub, _ := bip32.NewKeyFromString(xpub)
+	magicNumberOfInheritance := 3 //2+1; 2: because of the way spv-wallet stores xpubs in db; 1: to make a PKI
+	var err error
+	for i := 0; i < magicNumberOfInheritance; i++ {
+		xPub, err = xPub.Child(0)
+		if err != nil {
+			panic(err)
+		}
+	}
+
+	pubKey, err := xPub.ECPubKey()
+	if err != nil {
+		panic(err)
+	}
+
+	return hex.EncodeToString(pubKey.SerialiseCompressed())
+}