diff --git a/go.mod b/go.mod
index 0b2f4d3..831b52f 100644
--- a/go.mod
+++ b/go.mod
@@ -6,6 +6,7 @@ require (
 	github.com/google/uuid v1.6.0
 	github.com/gorilla/sessions v1.3.0
 	github.com/stretchr/testify v1.9.0
+	golang.org/x/sync v0.7.0
 	golang.org/x/time v0.5.0
 )
 
diff --git a/go.sum b/go.sum
index 1a063d6..6e99a11 100644
--- a/go.sum
+++ b/go.sum
@@ -14,6 +14,8 @@ github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
 github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/time v0.5.0 h1:o7cqy6amK/52YcAKIPlM3a+Fpj35zvRj2TP+e1xFSfk=
 golang.org/x/time v0.5.0/go.mod h1:3BpzKBy/shNhVucY/MWOyx10tF3SFh9QdLuxbVysPQM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
diff --git a/jwt.go b/jwt.go
index de84ba1..60f15be 100644
--- a/jwt.go
+++ b/jwt.go
@@ -10,7 +10,10 @@ import (
 	"encoding/pem"
 	"fmt"
 	"strings"
+	"sync"
 	"time"
+
+	"golang.org/x/sync/errgroup"
 )
 
 type JWT struct {
@@ -72,12 +75,47 @@ func verifyExpiration(expiration float64) error {
 	return nil
 }
 
-func verifySignature(token string, publicKeyPEM []byte) error {
+func (t *TraefikOidc) verifySignatureConcurrently(token string, publicKeys map[string][]byte) error {
 	parts := strings.Split(token, ".")
 	if len(parts) != 3 {
 		return fmt.Errorf("invalid token format")
 	}
 
+	signedContent := parts[0] + "." + parts[1]
+	signature, err := base64.RawURLEncoding.DecodeString(parts[2])
+	if err != nil {
+		return fmt.Errorf("failed to decode signature: %w", err)
+	}
+
+	var eg errgroup.Group
+	var mu sync.Mutex
+	var verificationSuccess bool
+
+	for _, publicKeyPEM := range publicKeys {
+		publicKeyPEM := publicKeyPEM // Create a new variable for the goroutine
+		eg.Go(func() error {
+			err := verifySignature(signedContent, signature, publicKeyPEM)
+			if err == nil {
+				mu.Lock()
+				verificationSuccess = true
+				mu.Unlock()
+			}
+			return nil // Always return nil to continue checking other keys
+		})
+	}
+
+	if err := eg.Wait(); err != nil {
+		return err
+	}
+
+	if !verificationSuccess {
+		return fmt.Errorf("signature verification failed for all keys")
+	}
+
+	return nil
+}
+
+func verifySignature(signedContent string, signature []byte, publicKeyPEM []byte) error {
 	block, _ := pem.Decode(publicKeyPEM)
 	if block == nil {
 		return fmt.Errorf("failed to parse PEM block containing the public key")
@@ -93,12 +131,6 @@ func verifySignature(token string, publicKeyPEM []byte) error {
 		return fmt.Errorf("not an RSA public key")
 	}
 
-	signedContent := parts[0] + "." + parts[1]
-	signature, err := base64.RawURLEncoding.DecodeString(parts[2])
-	if err != nil {
-		return fmt.Errorf("failed to decode signature: %w", err)
-	}
-
 	hash := sha256.Sum256([]byte(signedContent))
 	err = rsa.VerifyPKCS1v15(rsaPublicKey, crypto.SHA256, hash[:], signature)
 	if err != nil {
diff --git a/main.go b/main.go
index 2116e10..70030af 100644
--- a/main.go
+++ b/main.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"net"
 	"net/http"
 	"net/url"
 	"strings"
@@ -96,12 +97,22 @@ func (t *TraefikOidc) VerifyJWTSignatureAndClaims(jwt *JWT, token string) error
 		return fmt.Errorf("missing key ID in token header")
 	}
 
-	publicKeyPEM, err := getPublicKeyPEM(jwks, kid)
-	if err != nil {
-		return err
+	publicKeys := make(map[string][]byte)
+	for _, key := range jwks.Keys {
+		if key.Kid == kid {
+			publicKeyPEM, err := jwkToPEM(&key)
+			if err != nil {
+				return err
+			}
+			publicKeys[key.Kid] = publicKeyPEM
+		}
 	}
 
-	if err := verifySignature(token, publicKeyPEM); err != nil {
+	if len(publicKeys) == 0 {
+		return fmt.Errorf("no matching public keys found")
+	}
+
+	if err := t.verifySignatureConcurrently(token, publicKeys); err != nil {
 		return fmt.Errorf("signature verification failed: %w", err)
 	}
 
@@ -123,6 +134,28 @@ func New(ctx context.Context, next http.Handler, config *Config, name string) (h
 		return nil, fmt.Errorf("failed to discover provider metadata: %w", err)
 	}
 
+	transport := &http.Transport{
+		Proxy: http.ProxyFromEnvironment,
+		DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+			dialer := &net.Dialer{
+				Timeout:   30 * time.Second,
+				KeepAlive: 30 * time.Second,
+			}
+			return dialer.DialContext(ctx, network, addr)
+		},
+		ForceAttemptHTTP2:     true,
+		MaxIdleConns:          100,
+		IdleConnTimeout:       90 * time.Second,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
+		MaxIdleConnsPerHost:   10,
+	}
+
+	httpClient := &http.Client{
+		Timeout:   time.Second * 30,
+		Transport: transport,
+	}
+
 	t := &TraefikOidc{
 		next:           next,
 		name:           name,
@@ -141,7 +174,7 @@ func New(ctx context.Context, next http.Handler, config *Config, name string) (h
 		scopes:         config.Scopes,
 		limiter:        rate.NewLimiter(rate.Every(time.Second), config.RateLimit),
 		tokenCache:     NewTokenCache(),
-		httpClient:     &http.Client{},
+		httpClient:     httpClient,
 		logger:         NewLogger(config.LogLevel),
 		redirectURL:    "",
 	}
diff --git a/vendor/golang.org/x/sync/LICENSE b/vendor/golang.org/x/sync/LICENSE
new file mode 100644
index 0000000..6a66aea
--- /dev/null
+++ b/vendor/golang.org/x/sync/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/golang.org/x/sync/PATENTS b/vendor/golang.org/x/sync/PATENTS
new file mode 100644
index 0000000..7330990
--- /dev/null
+++ b/vendor/golang.org/x/sync/PATENTS
@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.
diff --git a/vendor/golang.org/x/sync/errgroup/errgroup.go b/vendor/golang.org/x/sync/errgroup/errgroup.go
new file mode 100644
index 0000000..948a3ee
--- /dev/null
+++ b/vendor/golang.org/x/sync/errgroup/errgroup.go
@@ -0,0 +1,135 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package errgroup provides synchronization, error propagation, and Context
+// cancelation for groups of goroutines working on subtasks of a common task.
+//
+// [errgroup.Group] is related to [sync.WaitGroup] but adds handling of tasks
+// returning errors.
+package errgroup
+
+import (
+	"context"
+	"fmt"
+	"sync"
+)
+
+type token struct{}
+
+// A Group is a collection of goroutines working on subtasks that are part of
+// the same overall task.
+//
+// A zero Group is valid, has no limit on the number of active goroutines,
+// and does not cancel on error.
+type Group struct {
+	cancel func(error)
+
+	wg sync.WaitGroup
+
+	sem chan token
+
+	errOnce sync.Once
+	err     error
+}
+
+func (g *Group) done() {
+	if g.sem != nil {
+		<-g.sem
+	}
+	g.wg.Done()
+}
+
+// WithContext returns a new Group and an associated Context derived from ctx.
+//
+// The derived Context is canceled the first time a function passed to Go
+// returns a non-nil error or the first time Wait returns, whichever occurs
+// first.
+func WithContext(ctx context.Context) (*Group, context.Context) {
+	ctx, cancel := withCancelCause(ctx)
+	return &Group{cancel: cancel}, ctx
+}
+
+// Wait blocks until all function calls from the Go method have returned, then
+// returns the first non-nil error (if any) from them.
+func (g *Group) Wait() error {
+	g.wg.Wait()
+	if g.cancel != nil {
+		g.cancel(g.err)
+	}
+	return g.err
+}
+
+// Go calls the given function in a new goroutine.
+// It blocks until the new goroutine can be added without the number of
+// active goroutines in the group exceeding the configured limit.
+//
+// The first call to return a non-nil error cancels the group's context, if the
+// group was created by calling WithContext. The error will be returned by Wait.
+func (g *Group) Go(f func() error) {
+	if g.sem != nil {
+		g.sem <- token{}
+	}
+
+	g.wg.Add(1)
+	go func() {
+		defer g.done()
+
+		if err := f(); err != nil {
+			g.errOnce.Do(func() {
+				g.err = err
+				if g.cancel != nil {
+					g.cancel(g.err)
+				}
+			})
+		}
+	}()
+}
+
+// TryGo calls the given function in a new goroutine only if the number of
+// active goroutines in the group is currently below the configured limit.
+//
+// The return value reports whether the goroutine was started.
+func (g *Group) TryGo(f func() error) bool {
+	if g.sem != nil {
+		select {
+		case g.sem <- token{}:
+			// Note: this allows barging iff channels in general allow barging.
+		default:
+			return false
+		}
+	}
+
+	g.wg.Add(1)
+	go func() {
+		defer g.done()
+
+		if err := f(); err != nil {
+			g.errOnce.Do(func() {
+				g.err = err
+				if g.cancel != nil {
+					g.cancel(g.err)
+				}
+			})
+		}
+	}()
+	return true
+}
+
+// SetLimit limits the number of active goroutines in this group to at most n.
+// A negative value indicates no limit.
+//
+// Any subsequent call to the Go method will block until it can add an active
+// goroutine without exceeding the configured limit.
+//
+// The limit must not be modified while any goroutines in the group are active.
+func (g *Group) SetLimit(n int) {
+	if n < 0 {
+		g.sem = nil
+		return
+	}
+	if len(g.sem) != 0 {
+		panic(fmt.Errorf("errgroup: modify limit while %v goroutines in the group are still active", len(g.sem)))
+	}
+	g.sem = make(chan token, n)
+}
diff --git a/vendor/golang.org/x/sync/errgroup/go120.go b/vendor/golang.org/x/sync/errgroup/go120.go
new file mode 100644
index 0000000..f93c740
--- /dev/null
+++ b/vendor/golang.org/x/sync/errgroup/go120.go
@@ -0,0 +1,13 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.20
+
+package errgroup
+
+import "context"
+
+func withCancelCause(parent context.Context) (context.Context, func(error)) {
+	return context.WithCancelCause(parent)
+}
diff --git a/vendor/golang.org/x/sync/errgroup/pre_go120.go b/vendor/golang.org/x/sync/errgroup/pre_go120.go
new file mode 100644
index 0000000..88ce334
--- /dev/null
+++ b/vendor/golang.org/x/sync/errgroup/pre_go120.go
@@ -0,0 +1,14 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.20
+
+package errgroup
+
+import "context"
+
+func withCancelCause(parent context.Context) (context.Context, func(error)) {
+	ctx, cancel := context.WithCancel(parent)
+	return ctx, func(error) { cancel() }
+}
diff --git a/vendor/modules.txt b/vendor/modules.txt
index 3b4c79b..19852e3 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -22,6 +22,9 @@ github.com/stretchr/testify/assert
 github.com/stretchr/testify/mock
 github.com/stretchr/testify/require
 github.com/stretchr/testify/suite
+# golang.org/x/sync v0.7.0
+## explicit; go 1.18
+golang.org/x/sync/errgroup
 # golang.org/x/time v0.5.0
 ## explicit; go 1.18
 golang.org/x/time/rate