diff --git a/example/client/app/app.go b/example/client/app/app.go
index 448c530..0b9b19d 100644
--- a/example/client/app/app.go
+++ b/example/client/app/app.go
@@ -56,6 +56,7 @@ func main() {
 		rp.WithVerifierOpts(rp.WithIssuedAtOffset(5 * time.Second)),
 		rp.WithHTTPClient(client),
 		rp.WithLogger(logger),
+		rp.WithSigningAlgsFromDiscovery(),
 	}
 	if clientSecret == "" {
 		options = append(options, rp.WithPKCE(cookieHandler))
diff --git a/pkg/crypto/hash.go b/pkg/crypto/hash.go
index ab9f8c1..14acdee 100644
--- a/pkg/crypto/hash.go
+++ b/pkg/crypto/hash.go
@@ -21,6 +21,14 @@ func GetHashAlgorithm(sigAlgorithm jose.SignatureAlgorithm) (hash.Hash, error) {
 		return sha512.New384(), nil
 	case jose.RS512, jose.ES512, jose.PS512:
 		return sha512.New(), nil
+
+	// There is no published spec for this yet, but we have confirmation it will get published.
+	// There is consensus here: https://bitbucket.org/openid/connect/issues/1125/_hash-algorithm-for-eddsa-id-tokens
+	// Currently Go and go-jose only supports the ed25519 curve key for EdDSA, so we can safely assume sha512 here.
+	// It is unlikely ed448 will ever be supported: https://github.com/golang/go/issues/29390
+	case jose.EdDSA:
+		return sha512.New(), nil
+
 	default:
 		return nil, fmt.Errorf("%w: %q", ErrUnsupportedAlgorithm, sigAlgorithm)
 	}
diff --git a/pkg/oidc/keyset.go b/pkg/oidc/keyset.go
index 833878d..a8b89b0 100644
--- a/pkg/oidc/keyset.go
+++ b/pkg/oidc/keyset.go
@@ -6,6 +6,7 @@ import (
 	"crypto/ed25519"
 	"crypto/rsa"
 	"errors"
+	"strings"
 
 	jose "github.com/go-jose/go-jose/v4"
 )
@@ -92,17 +93,17 @@ func FindMatchingKey(keyID, use, expectedAlg string, keys ...jose.JSONWebKey) (k
 }
 
 func algToKeyType(key any, alg string) bool {
-	switch alg[0] {
-	case 'R', 'P':
+	if strings.HasPrefix(alg, "RS") || strings.HasPrefix(alg, "PS") {
 		_, ok := key.(*rsa.PublicKey)
 		return ok
-	case 'E':
+	}
+	if strings.HasPrefix(alg, "ES") {
 		_, ok := key.(*ecdsa.PublicKey)
 		return ok
-	case 'O':
-		_, ok := key.(*ed25519.PublicKey)
-		return ok
-	default:
-		return false
 	}
+	if alg == string(jose.EdDSA) {
+		_, ok := key.(ed25519.PublicKey)
+		return ok
+	}
+	return false
 }
diff --git a/pkg/op/auth_request.go b/pkg/op/auth_request.go
index fe73180..52fda2e 100644
--- a/pkg/op/auth_request.go
+++ b/pkg/op/auth_request.go
@@ -83,19 +83,27 @@ func Authorize(w http.ResponseWriter, r *http.Request, authorizer Authorizer) {
 	if authReq.RequestParam != "" && authorizer.RequestObjectSupported() {
 		err = ParseRequestObject(ctx, authReq, authorizer.Storage(), IssuerFromContext(ctx))
 		if err != nil {
-			AuthRequestError(w, r, authReq, err, authorizer)
+			AuthRequestError(w, r, nil, err, authorizer)
 			return
 		}
 	}
 	if authReq.ClientID == "" {
-		AuthRequestError(w, r, authReq, fmt.Errorf("auth request is missing client_id"), authorizer)
+		AuthRequestError(w, r, nil, fmt.Errorf("auth request is missing client_id"), authorizer)
 		return
 	}
 	if authReq.RedirectURI == "" {
-		AuthRequestError(w, r, authReq, fmt.Errorf("auth request is missing redirect_uri"), authorizer)
+		AuthRequestError(w, r, nil, fmt.Errorf("auth request is missing redirect_uri"), authorizer)
 		return
 	}
-	validation := ValidateAuthRequest
+
+	var client Client
+	validation := func(ctx context.Context, authReq *oidc.AuthRequest, storage Storage, verifier *IDTokenHintVerifier) (sub string, err error) {
+		client, err = authorizer.Storage().GetClientByClientID(ctx, authReq.ClientID)
+		if err != nil {
+			return "", oidc.ErrInvalidRequestRedirectURI().WithDescription("unable to retrieve client by id").WithParent(err)
+		}
+		return ValidateAuthRequestClient(ctx, authReq, client, verifier)
+	}
 	if validater, ok := authorizer.(AuthorizeValidator); ok {
 		validation = validater.ValidateAuthRequest
 	}
@@ -113,11 +121,6 @@ func Authorize(w http.ResponseWriter, r *http.Request, authorizer Authorizer) {
 		AuthRequestError(w, r, authReq, oidc.DefaultToServerError(err, "unable to save auth request"), authorizer)
 		return
 	}
-	client, err := authorizer.Storage().GetClientByClientID(ctx, req.GetClientID())
-	if err != nil {
-		AuthRequestError(w, r, req, oidc.DefaultToServerError(err, "unable to retrieve client by id"), authorizer)
-		return
-	}
 	RedirectToLogin(req.GetID(), client, w, r)
 }
 
@@ -212,26 +215,37 @@ func CopyRequestObjectToAuthRequest(authReq *oidc.AuthRequest, requestObject *oi
 	authReq.RequestParam = ""
 }
 
-// ValidateAuthRequest validates the authorize parameters and returns the userID of the id_token_hint if passed
+// ValidateAuthRequest validates the authorize parameters and returns the userID of the id_token_hint if passed.
+//
+// Deprecated: Use [ValidateAuthRequestClient] to prevent querying for the Client twice.
 func ValidateAuthRequest(ctx context.Context, authReq *oidc.AuthRequest, storage Storage, verifier *IDTokenHintVerifier) (sub string, err error) {
 	ctx, span := tracer.Start(ctx, "ValidateAuthRequest")
 	defer span.End()
 
+	client, err := storage.GetClientByClientID(ctx, authReq.ClientID)
+	if err != nil {
+		return "", oidc.ErrInvalidRequestRedirectURI().WithDescription("unable to retrieve client by id").WithParent(err)
+	}
+	return ValidateAuthRequestClient(ctx, authReq, client, verifier)
+}
+
+// ValidateAuthRequestClient validates the Auth request against the passed client.
+// If id_token_hint is part of the request, the subject of the token is returned.
+func ValidateAuthRequestClient(ctx context.Context, authReq *oidc.AuthRequest, client Client, verifier *IDTokenHintVerifier) (sub string, err error) {
+	ctx, span := tracer.Start(ctx, "ValidateAuthRequestClient")
+	defer span.End()
+
+	if err := ValidateAuthReqRedirectURI(client, authReq.RedirectURI, authReq.ResponseType); err != nil {
+		return "", err
+	}
 	authReq.MaxAge, err = ValidateAuthReqPrompt(authReq.Prompt, authReq.MaxAge)
 	if err != nil {
 		return "", err
 	}
-	client, err := storage.GetClientByClientID(ctx, authReq.ClientID)
-	if err != nil {
-		return "", oidc.DefaultToServerError(err, "unable to retrieve client by id")
-	}
 	authReq.Scopes, err = ValidateAuthReqScopes(client, authReq.Scopes)
 	if err != nil {
 		return "", err
 	}
-	if err := ValidateAuthReqRedirectURI(client, authReq.RedirectURI, authReq.ResponseType); err != nil {
-		return "", err
-	}
 	if err := ValidateAuthReqResponseType(client, authReq.ResponseType); err != nil {
 		return "", err
 	}