diff --git a/apps/api/internal/httpapi/oidc_session.go b/apps/api/internal/httpapi/oidc_session.go
index 037cb84..0b21a2d 100644
--- a/apps/api/internal/httpapi/oidc_session.go
+++ b/apps/api/internal/httpapi/oidc_session.go
@@ -48,7 +48,7 @@ func (s *Server) startOIDCLogin(w http.ResponseWriter, r *http.Request) {
 	if returnTo == "" {
 		returnTo = "/"
 	}
-	transaction, _, err := oidcsession.NewLoginTransaction(returnTo, time.Now())
+	transaction, err := oidcsession.NewLoginTransaction(returnTo, time.Now())
 	if err != nil {
 		writeError(w, http.StatusBadRequest, "登录后返回地址无效", errorCodeOIDCLoginInvalid)
 		return
diff --git a/apps/api/internal/httpapi/oidc_session_test.go b/apps/api/internal/httpapi/oidc_session_test.go
index 0e6f351..9c3d442 100644
--- a/apps/api/internal/httpapi/oidc_session_test.go
+++ b/apps/api/internal/httpapi/oidc_session_test.go
@@ -66,7 +66,7 @@ func TestCompleteOIDCLoginReportsSafeTransactionFailureReason(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	transaction, _, err := oidcsession.NewLoginTransaction("/", time.Now())
+	transaction, err := oidcsession.NewLoginTransaction("/", time.Now())
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/apps/api/internal/oidcsession/login_transaction.go b/apps/api/internal/oidcsession/login_transaction.go
index f670263..ac5359f 100644
--- a/apps/api/internal/oidcsession/login_transaction.go
+++ b/apps/api/internal/oidcsession/login_transaction.go
@@ -2,7 +2,6 @@ package oidcsession
 
 import (
 	"crypto/rand"
-	"crypto/sha256"
 	"encoding/base64"
 	"errors"
 	"net/url"
@@ -22,25 +21,23 @@ type LoginTransaction struct {
 	CreatedAt    time.Time `json:"createdAt"`
 }
 
-func NewLoginTransaction(returnTo string, now time.Time) (LoginTransaction, string, error) {
+func NewLoginTransaction(returnTo string, now time.Time) (LoginTransaction, error) {
 	if !ValidReturnTo(returnTo) {
-		return LoginTransaction{}, "", errors.New("returnTo must be a same-origin relative path")
+		return LoginTransaction{}, errors.New("returnTo must be a same-origin relative path")
 	}
 	state, err := randomBase64URL(32)
 	if err != nil {
-		return LoginTransaction{}, "", err
+		return LoginTransaction{}, err
 	}
 	nonce, err := randomBase64URL(32)
 	if err != nil {
-		return LoginTransaction{}, "", err
+		return LoginTransaction{}, err
 	}
 	verifier, err := randomBase64URL(32)
 	if err != nil {
-		return LoginTransaction{}, "", err
+		return LoginTransaction{}, err
 	}
-	challengeHash := sha256.Sum256([]byte(verifier))
-	return LoginTransaction{State: state, Nonce: nonce, PKCEVerifier: verifier, ReturnTo: returnTo, CreatedAt: now.UTC()},
-		base64.RawURLEncoding.EncodeToString(challengeHash[:]), nil
+	return LoginTransaction{State: state, Nonce: nonce, PKCEVerifier: verifier, ReturnTo: returnTo, CreatedAt: now.UTC()}, nil
 }
 
 func (c *Cipher) EncodeLoginTransaction(transaction LoginTransaction) (string, error) {
diff --git a/apps/api/internal/oidcsession/login_transaction_test.go b/apps/api/internal/oidcsession/login_transaction_test.go
index c2bf43b..bdc8d73 100644
--- a/apps/api/internal/oidcsession/login_transaction_test.go
+++ b/apps/api/internal/oidcsession/login_transaction_test.go
@@ -7,15 +7,15 @@ import (
 	"time"
 )
 
-func TestLoginTransactionIsEncryptedBoundedAndPKCES256(t *testing.T) {
+func TestLoginTransactionIsEncryptedAndBounded(t *testing.T) {
 	now := time.Date(2026, 7, 13, 12, 0, 0, 0, time.UTC)
 	cipher, _ := NewCipher(bytes.Repeat([]byte{9}, 32))
-	transaction, challenge, err := NewLoginTransaction("/workspace?tab=wallet", now)
+	transaction, err := NewLoginTransaction("/workspace?tab=wallet", now)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if transaction.State == transaction.Nonce || len(challenge) != 43 || challenge == transaction.PKCEVerifier {
-		t.Fatal("state, nonce and PKCE values are not independent S256 material")
+	if transaction.State == transaction.Nonce || len(transaction.PKCEVerifier) != 43 || transaction.State == transaction.PKCEVerifier {
+		t.Fatal("state, nonce and PKCE verifier are not independent security material")
 	}
 	encoded, err := cipher.EncodeLoginTransaction(transaction)
 	if err != nil {