feat: Chunk ID namespace is now separated from the E2EE passphrase by introducing userHashSalt.

src/modules/features/SettingDialogue/PanePatches.ts

@@ -6,6 +6,7 @@ import {
     SuffixDatabaseName,
 } from "../../../lib/src/common/types.ts";
 import { Logger } from "../../../lib/src/common/logger.ts";
+import { generateUserHashSalt } from "../../../lib/src/common/utils.ts";
 import { LiveSyncSetting as Setting } from "./LiveSyncSetting.ts";
 import type { ObsidianLiveSyncSettingTab } from "./ObsidianLiveSyncSettingTab.ts";
 import type { PageFunctions } from "./SettingPane.ts";
@@ -156,6 +157,42 @@ export function panePatches(this: ObsidianLiveSyncSettingTab, paneEl: HTMLElemen
             await this.core.localDatabase._prepareHashFunctions();
         });
     });
+
+    void addPanel(paneEl, "Chunk ID Namespace").then((paneEl) => {
+        paneEl.createDiv({
+            text: "Manage the Chunk ID Namespace Salt (userHashSalt). This value is used as a seed for generating chunk IDs. If you change this value, chunk IDs will be regenerated and you must rebuild the database.",
+            cls: "op-warn-info",
+        });
+
+        new Setting(paneEl)
+            .autoWireText("userHashSalt", { holdValue: true })
+            .setClass("wizardHidden")
+            .addApplyButton(["userHashSalt"]);
+
+        new Setting(paneEl)
+            .setName("Generate New Salt")
+            .setDesc(
+                "Generate a new random salt for the Chunk ID namespace. After generating, a database rebuild is strongly recommended."
+            )
+            .addButton((button) => {
+                button
+                    .setButtonText("Generate New Salt")
+                    .setCta()
+                    .onClick(async () => {
+                        const confirmed = await this.core.confirm.askYesNo(
+                            "Generating a new salt will invalidate existing chunk IDs. Until you rebuild the database, deduplication will be inefficient. Are you sure to generate a new salt now?"
+                        );
+                        if (confirmed) {
+                            const newSalt = generateUserHashSalt();
+                            this.editingSettings.userHashSalt = newSalt;
+                            await this.saveSettings(["userHashSalt"]);
+                            Logger(`New Chunk ID Namespace Salt generated.`, LOG_LEVEL_NOTICE);
+                            this.requestUpdate();
+                        }
+                    });
+            });
+    });
+
     void addPanel(paneEl, "Edge case addressing (Behaviour)").then((paneEl) => {
         new Setting(paneEl).autoWireToggle("doNotSuspendOnFetching");
         new Setting(paneEl).setClass("wizardHidden").autoWireToggle("doNotDeleteFolder");

src/modules/features/SetupManager.ts

@@ -7,7 +7,7 @@ import {
     REMOTE_MINIO,
     REMOTE_P2P,
 } from "../../lib/src/common/types.ts";
-import { generatePatchObj, isObjectDifferent } from "../../lib/src/common/utils.ts";
+import { generatePatchObj, isObjectDifferent, generateUserHashSalt } from "../../lib/src/common/utils.ts";
 import Intro from "./SetupWizard/dialogs/Intro.svelte";
 import SelectMethodNewUser from "./SetupWizard/dialogs/SelectMethodNewUser.svelte";
 import SelectMethodExisting from "./SetupWizard/dialogs/SelectMethodExisting.svelte";
@@ -328,6 +328,9 @@ export class SetupManager extends AbstractModule {
         }
         if (confirm) {
             extra();
+            if (userMode === UserMode.NewUser && !newConf.userHashSalt) {
+                newConf.userHashSalt = generateUserHashSalt();
+            }
             await this.applySetting(newConf, userMode);
             if (userMode === UserMode.NewUser) {
                 // For new users, schedule a rebuild everything.

src/modules/features/SetupManager.unit.spec.ts

@@ -154,4 +154,47 @@ describe("SetupManager", () => {
         );
         expect(setting.currentSettings().activeConfigurationId).toBe("legacy-couchdb");
     });
+
+    it("onConfirmApplySettingsFromWizard should generate userHashSalt for NewUser when absent", async () => {
+        const { manager, setting, dialogManager, core } = createSetupManager();
+        const randomSpy = vi.spyOn(globalThis.crypto, "getRandomValues").mockImplementation((array) => {
+            const target = array as Uint8Array;
+            for (let i = 0; i < target.length; i++) {
+                target[i] = 0xab;
+            }
+            return array;
+        });
+        dialogManager.openWithExplicitCancel.mockResolvedValueOnce(true);
+
+        await manager.onConfirmApplySettingsFromWizard(
+            {
+                ...setting.currentSettings(),
+                userHashSalt: "",
+            },
+            UserMode.NewUser
+        );
+
+        expect(setting.currentSettings().userHashSalt).toBe("abababababababababababababababab");
+        expect(core.rebuilder.scheduleRebuild).toHaveBeenCalledTimes(1);
+        randomSpy.mockRestore();
+    });
+
+    it("onConfirmApplySettingsFromWizard should keep existing userHashSalt for NewUser", async () => {
+        const { manager, setting, dialogManager, core } = createSetupManager();
+        const randomSpy = vi.spyOn(globalThis.crypto, "getRandomValues");
+        dialogManager.openWithExplicitCancel.mockResolvedValueOnce(true);
+
+        await manager.onConfirmApplySettingsFromWizard(
+            {
+                ...setting.currentSettings(),
+                userHashSalt: "00112233445566778899aabbccddeeff",
+            },
+            UserMode.NewUser
+        );
+
+        expect(setting.currentSettings().userHashSalt).toBe("00112233445566778899aabbccddeeff");
+        expect(randomSpy).not.toHaveBeenCalled();
+        expect(core.rebuilder.scheduleRebuild).toHaveBeenCalledTimes(1);
+        randomSpy.mockRestore();
+    });
 });