Changeset 0.10.0 (#56)

server/handlers/settings.go

@@ -3,12 +3,14 @@ package handlers
 import (
 	"database/sql"
 	"encoding/json"
+	"log"
 	"net/http"
 	"strings"
 
 	"github.com/gin-gonic/gin"
 	"golang.org/x/crypto/bcrypt"
 
+	"git.gobha.me/xcaliber/chat-switchboard/crypto"
 	"git.gobha.me/xcaliber/chat-switchboard/database"
 )
 
@@ -36,11 +38,13 @@ type profileResponse struct {
 }
 
 // SettingsHandler manages user profile and preferences.
-type SettingsHandler struct{}
+type SettingsHandler struct {
+	uekCache *crypto.UEKCache
+}
 
 // NewSettingsHandler creates a new handler.
-func NewSettingsHandler() *SettingsHandler {
-	return &SettingsHandler{}
+func NewSettingsHandler(uekCache *crypto.UEKCache) *SettingsHandler {
+	return &SettingsHandler{uekCache: uekCache}
 }
 
 // ── Get Profile ─────────────────────────────
@@ -155,6 +159,9 @@ func (h *SettingsHandler) ChangePassword(c *gin.Context) {
 		return
 	}
 
+	// Re-wrap UEK with new password so personal BYOK keys remain accessible
+	h.rewrapVault(userID, req.CurrentPassword, req.NewPassword)
+
 	c.JSON(http.StatusOK, gin.H{"message": "password updated"})
 }
 
@@ -207,3 +214,60 @@ func (h *SettingsHandler) UpdateSettings(c *gin.Context) {
 
 	h.GetSettings(c)
 }
+
+// ── Vault Re-wrap ──────────────────────────
+
+// rewrapVault decrypts the UEK with the old password and re-encrypts it with
+// the new password. This keeps personal BYOK keys accessible after a password
+// change. Uses a new salt for forward secrecy.
+func (h *SettingsHandler) rewrapVault(userID, oldPassword, newPassword string) {
+	if h.uekCache == nil {
+		return
+	}
+
+	var vaultSet bool
+	var encUEK, salt, nonce []byte
+	err := database.DB.QueryRow(`
+		SELECT vault_set, encrypted_uek, uek_salt, uek_nonce
+		FROM users WHERE id = $1
+	`, userID).Scan(&vaultSet, &encUEK, &salt, &nonce)
+	if err != nil || !vaultSet || len(encUEK) == 0 {
+		return // No vault to re-wrap
+	}
+
+	// Decrypt UEK with old password
+	oldPDK := crypto.DeriveKeyFromPassword(oldPassword, salt)
+	uek, err := crypto.UnwrapUEK(encUEK, nonce, oldPDK)
+	if err != nil {
+		log.Printf("⚠ Vault re-wrap failed for user %s (unwrap): %v", userID, err)
+		return
+	}
+
+	// Re-wrap with new password using fresh salt
+	newSalt, err := crypto.GenerateSalt()
+	if err != nil {
+		log.Printf("⚠ Vault re-wrap failed for user %s (salt): %v", userID, err)
+		return
+	}
+
+	newPDK := crypto.DeriveKeyFromPassword(newPassword, newSalt)
+	newEncUEK, newNonce, err := crypto.WrapUEK(uek, newPDK)
+	if err != nil {
+		log.Printf("⚠ Vault re-wrap failed for user %s (wrap): %v", userID, err)
+		return
+	}
+
+	_, err = database.DB.Exec(`
+		UPDATE users
+		SET encrypted_uek = $1, uek_salt = $2, uek_nonce = $3, updated_at = NOW()
+		WHERE id = $4
+	`, newEncUEK, newSalt, newNonce, userID)
+	if err != nil {
+		log.Printf("⚠ Vault re-wrap failed for user %s (persist): %v", userID, err)
+		return
+	}
+
+	// Session cache: UEK itself hasn't changed, just its wrapper
+	h.uekCache.Store(userID, uek)
+	log.Printf("  🔐 Vault re-wrapped for user %s", userID)
+}