moved ValidateTokenSignature to jwk and added tests

tools/auth/apple.go

@@ -4,8 +4,10 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 
 	"github.com/golang-jwt/jwt/v5"
+	"github.com/pocketbase/pocketbase/tools/auth/internal/jwk"
 	"github.com/pocketbase/pocketbase/tools/types"
 	"github.com/spf13/cast"
 	"golang.org/x/oauth2"
@@ -108,10 +110,10 @@ func (p *Apple) parseAndVerifyIdToken(idToken string) (jwt.MapClaims, error) {
 		return nil, errors.New("empty id_token")
 	}
 
-	// extract the token header params and claims
+	// extract the token claims
 	// ---
 	claims := jwt.MapClaims{}
-	t, _, err := jwt.NewParser().ParseUnverified(idToken, claims)
+	_, _, err := jwt.NewParser().ParseUnverified(idToken, claims)
 	if err != nil {
 		return nil, err
 	}
@@ -136,10 +138,9 @@ func (p *Apple) parseAndVerifyIdToken(idToken string) (jwt.MapClaims, error) {
 	// the token which is a result of direct TLS communication with the provider
 	// (see also https://openid.net/specs/openid-connect-core-1_0.html#IDTokenValidation)
 	// ---
-	kid, _ := t.Header["kid"].(string)
-	err = validateIdTokenSignature(p.ctx, idToken, p.jwksURL, kid)
+	err = jwk.ValidateTokenSignature(p.ctx, idToken, p.jwksURL)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("id_token validation failed: %w", err)
 	}
 
 	return claims, nil

tools/auth/internal/jwk/jwk.go

@@ -8,11 +8,14 @@ import (
 	"crypto/rsa"
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"math/big"
 	"net/http"
 	"strings"
+
+	"github.com/golang-jwt/jwt/v5"
 )
 
 type JWK struct {
@@ -94,7 +97,7 @@ func Fetch(ctx context.Context, jwksURL string, kid string) (*JWK, error) {
 	// http.Client.Get doesn't treat non 2xx responses as error
 	if res.StatusCode >= 400 {
 		return nil, fmt.Errorf(
-			"failed to JSON Web Key Set from %s (%d):\n%s",
+			"failed to fetch JSON Web Key Set from %s (%d):\n%s",
 			jwksURL,
 			res.StatusCode,
 			string(rawBody),
@@ -116,5 +119,45 @@ func Fetch(ctx context.Context, jwksURL string, kid string) (*JWK, error) {
 		}
 	}
 
-	return nil, fmt.Errorf("jwk with kid %q was not found", kid)
+	return nil, fmt.Errorf("JWK with kid %q was not found", kid)
+}
+
+// ValidateTokenSignature validates the signature of a token with the
+// public key retrievied from a remote JWKS.
+func ValidateTokenSignature(ctx context.Context, token string, jwksURL string) error {
+	// extract the kid token header
+	// ---
+	t, _, err := jwt.NewParser().ParseUnverified(token, jwt.MapClaims{})
+	if err != nil {
+		return err
+	}
+
+	kid, _ := t.Header["kid"].(string)
+	if kid == "" {
+		return errors.New("missing kid header value")
+	}
+
+	// fetch the public key set
+	// ---
+	key, err := Fetch(ctx, jwksURL, kid)
+	if err != nil {
+		return err
+	}
+
+	// verify the signature
+	// ---
+	parser := jwt.NewParser(jwt.WithValidMethods([]string{key.Alg}))
+
+	parsedToken, err := parser.Parse(token, func(t *jwt.Token) (any, error) {
+		return key.PublicKey()
+	})
+	if err != nil {
+		return err
+	}
+
+	if !parsedToken.Valid {
+		return errors.New("the parsed token is invalid")
+	}
+
+	return nil
 }

tools/auth/internal/jwk/jwk_test.go

@@ -15,6 +15,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/golang-jwt/jwt/v5"
 	"github.com/pocketbase/pocketbase/tools/auth/internal/jwk"
 )
 
@@ -27,7 +28,7 @@ func TestJWK_PublicKey(t *testing.T) {
 
 	rsaPrivate, err := rsa.GenerateKey(rand.Reader, 1024)
 	if err != nil {
-		t.Fatalf("failed to generate test RSA private key: %v", err)
+		t.Fatal(err)
 	}
 
 	scenarios := []struct {
@@ -209,3 +210,105 @@ func TestFetch(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateTokenSignature(t *testing.T) {
+	t.Parallel()
+
+	rsaPrivate, err := rsa.GenerateKey(rand.Reader, 1024)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ed25519Public, ed25519Private, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	nonmatchingKidToken := jwt.New(&jwt.SigningMethodEd25519{})
+	nonmatchingKidToken.Header["kid"] = "missing"
+	nonmatchingKidTokenStr, err := nonmatchingKidToken.SignedString(ed25519Private)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	key1Token := jwt.New(&jwt.SigningMethodEd25519{})
+	key1Token.Header["kid"] = "key1"
+	key1TokenStr, err := key1Token.SignedString(ed25519Private)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	key2Token := jwt.New(jwt.SigningMethodRS256)
+	key2Token.Header["kid"] = "key2"
+	key2TokenStr, err := key2Token.SignedString(rsaPrivate)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	server := httptest.NewServer(http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
+		_ = json.NewEncoder(res).Encode(map[string]any{"keys": []*jwk.JWK{
+			{
+				Kid: "key1",
+				Kty: "OKP",
+				Alg: "EdDSA",
+				Crv: "Ed25519",
+				X:   base64.RawURLEncoding.EncodeToString(ed25519Public),
+			},
+			{
+				Kid: "key2",
+				Kty: "RSA",
+				Alg: "RS256",
+				E:   base64.RawURLEncoding.EncodeToString(big.NewInt(int64(rsaPrivate.E)).Bytes()),
+				N:   base64.RawURLEncoding.EncodeToString(rsaPrivate.N.Bytes()),
+			},
+		}})
+	}))
+	defer server.Close()
+
+	scenarios := []struct {
+		name        string
+		token       string
+		expectError bool
+	}{
+		{
+			"empty token",
+			"",
+			true,
+		},
+		{
+			"invlaid token",
+			"abc",
+			true,
+		},
+		{
+			"no matching kid",
+			nonmatchingKidTokenStr,
+			true,
+		},
+		{
+			"valid Ed25519 token",
+			key1TokenStr,
+			false,
+		},
+		{
+			"valid RSA token",
+			key2TokenStr,
+			false,
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.name, func(t *testing.T) {
+			err := jwk.ValidateTokenSignature(
+				context.Background(),
+				s.token,
+				server.URL,
+			)
+
+			hasErr := err != nil
+			if hasErr != s.expectError {
+				t.Fatalf("Expected hasErr %v, got %v (%v)", s.expectError, hasErr, err)
+			}
+		})
+	}
+}

tools/auth/oidc.go

@@ -135,7 +135,7 @@ func (p *OIDC) parseIdToken(token *oauth2.Token) (jwt.MapClaims, error) {
 	}
 
 	claims := jwt.MapClaims{}
-	t, _, err := jwt.NewParser().ParseUnverified(idToken, claims)
+	_, _, err := jwt.NewParser().ParseUnverified(idToken, claims)
 	if err != nil {
 		return nil, err
 	}
@@ -176,42 +176,11 @@ func (p *OIDC) parseIdToken(token *oauth2.Token) (jwt.MapClaims, error) {
 	// (see also https://openid.net/specs/openid-connect-core-1_0.html#IDTokenValidation)
 	jwksURL := cast.ToString(p.Extra()["jwksURL"])
 	if jwksURL != "" {
-		kid, _ := t.Header["kid"].(string)
-		err = validateIdTokenSignature(p.ctx, idToken, jwksURL, kid)
+		err = jwk.ValidateTokenSignature(p.ctx, idToken, jwksURL)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("id_token validation failed: %w", err)
 		}
 	}
 
 	return claims, nil
 }
-
-func validateIdTokenSignature(ctx context.Context, idToken string, jwksURL string, kid string) error {
-	// fetch the public key set
-	// ---
-	if kid == "" {
-		return errors.New("missing kid header value")
-	}
-
-	key, err := jwk.Fetch(ctx, jwksURL, kid)
-	if err != nil {
-		return err
-	}
-
-	// verify the signiture
-	// ---
-	parser := jwt.NewParser(jwt.WithValidMethods([]string{key.Alg}))
-
-	parsedToken, err := parser.Parse(idToken, func(t *jwt.Token) (any, error) {
-		return key.PublicKey()
-	})
-	if err != nil {
-		return err
-	}
-
-	if !parsedToken.Valid {
-		return errors.New("the parsed id_token is invalid")
-	}
-
-	return nil
-}