fix: use proper key format in ContinuityCookieManager and prevent panic in XChaCha20Poly1305

cipher/chacha20.go

@@ -76,7 +76,7 @@ func (c *XChaCha20Poly1305) Decrypt(ctx context.Context, ciphertext string) ([]b
 			return nil, errors.WithStack(herodot.ErrInternalServerError.WithWrap(err).WithReason("Unable to instantiate chacha20"))
 		}
 
-		if len(ciphertext) < aead.NonceSize() {
+		if len(rawCiphertext) < aead.NonceSize() {
 			return nil, errors.WithStack(herodot.ErrInternalServerError.WithReason("cipher text too short"))
 		}
 

cipher/cipher_test.go

@@ -73,6 +73,25 @@ func TestCipher(t *testing.T) {
 				_, err = c.Decrypt(contextx.WithConfigValue(ctx, config.ViperKeySecretsCipher, []string{""}), "not-empty")
 				require.Error(t, err)
 			})
+
+			t.Run("case=short_ciphertext", func(t *testing.T) {
+				t.Parallel()
+
+				// XChaCha20-Poly1305 has 24-byte nonce, hex encoded is 48 chars
+				// A valid ciphertext needs at least 24 bytes (nonce) + 16 bytes (tag) = 40 bytes minimum
+				// Hex encoded minimum is 80 chars
+				// This tests that we don't get panic on short ciphertext
+
+				// 24 hex chars is only 12 bytes - less than nonce size (24 bytes)
+				shortCiphertext := "00112233445566778899aabbccddeeff"
+				_, err := c.Decrypt(ctx, shortCiphertext)
+				require.Error(t, err)
+
+				// 64 hex chars is 32 bytes - still less than nonce(24)+tag(16)=40
+				mediumCiphertext := "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff"
+				_, err = c.Decrypt(ctx, mediumCiphertext)
+				require.Error(t, err)
+			})
 		})
 	}
 

driver/registry_default.go

@@ -547,7 +547,13 @@ func (m *RegistryDefault) CookieManager(ctx context.Context) sessions.StoreExact
 
 func (m *RegistryDefault) ContinuityCookieManager(ctx context.Context) sessions.StoreExact {
 	// To support hot reloading, this can not be instantiated only once.
-	cs := sessions.NewCookieStore(m.Config().SecretsSession(ctx)...)
+	var keys [][]byte
+	for _, k := range m.Config().SecretsSession(ctx) {
+		encrypt := sha256.Sum256(k)
+		keys = append(keys, k, encrypt[:])
+	}
+
+	cs := sessions.NewCookieStore(keys...)
 	cs.Options.Secure = m.Config().CookieSecure(ctx)
 	cs.Options.HttpOnly = true
 	cs.Options.SameSite = http.SameSiteLaxMode

driver/registry_default_test.go

@@ -6,6 +6,8 @@
 import (
 	"context"
 	"fmt"
+	"net/http"
+	"net/http/httptest"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -969,3 +971,53 @@
 		}
 	})
 }
+
+func TestContinuityCookieManager_Keys(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	_, reg := internal.NewVeryFastRegistryWithoutDB(t)
+
+	t.Run("supports key rotation", func(t *testing.T) {
+		t.Parallel()
+
+		secret := "secret-key-32-bytes-long-xxxxx"
+		secret2 := "another-32-bytes-secret-keyyyy"
+
+		// Step 1: Create registry with first secret and save a cookie
+		ctx1 := contextx.WithConfigValues(ctx, map[string]any{
+			config.ViperKeySecretsCookie: []string{secret},
+		})
+
+		store1 := reg.ContinuityCookieManager(ctx1)
+		require.NotNil(t, store1)
+
+		// Save a session cookie
+		r1 := &http.Request{Header: http.Header{}}
+		w1 := httptest.NewRecorder()
+		session1, err := store1.New(r1, "test_session")
+		require.NoError(t, err)
+		session1.Values["test_key"] = "test_value"
+		err = session1.Save(r1, w1)
+		require.NoError(t, err)
+
+		cookies := w1.Result().Cookies()
+		require.Len(t, cookies, 1)
+		cookie := cookies[0]
+
+		// Step 2: Create registry with two secrets (new + old for rotation)
+		ctx2 := contextx.WithConfigValues(context.Background(), map[string]any{
+			config.ViperKeySecretsCookie: []string{secret2, secret},
+		})
+		store2 := reg.ContinuityCookieManager(ctx2)
+		require.NotNil(t, store2)
+
+		// Step 3: Read the original cookie with the new registry
+		// This should work because the second secret matches the original
+		r2 := &http.Request{Header: http.Header{}}
+		r2.AddCookie(cookie)
+
+		session2, err := store2.Get(r2, "test_session")
+		require.NoError(t, err, "should be able to read cookie with rotated keys")
+		assert.Equal(t, "test_value", session2.Values["test_key"])
+	})
+}