Sauci/docs/remove-e2ee-plan.md

Plan: Remove E2EE and Switch to Server-Side Security

Overview

This document outlines the plan to remove end-to-end encryption (E2EE) from Sauci's chat system and rely on Supabase's built-in security instead.

Current State

• Messages are encrypted client-side using AES-256-GCM with triple-wrapped RSA keys
• Each message has sender, recipient, and admin wrapped keys
• Complex key management: generation, storage, rotation, recovery
• ~2500+ lines of encryption code across 21 files
• Edge functions handle key rotation and pending message re-encryption

Target State

• Messages stored as plaintext in Supabase (protected by RLS policies)
• TLS encryption in transit (Supabase default)
• Encryption at rest (Supabase infrastructure)
• No client-side key management
• Simplified chat code

Why Remove E2EE?

1. Complexity - Triple-wrapped keys, device recovery, key rotation adds significant maintenance burden
2. Overkill - For a couples intimacy app, server-side security is sufficient
3. User Experience - E2EE adds latency, recovery flows, and potential failure modes
4. Development Velocity - Simpler code = faster iteration

Security Model After Removal

• In Transit: TLS 1.3 (Supabase default)
• At Rest: Supabase encrypts data at rest
• Access Control: RLS policies restrict access to couple's own messages
• Admin Access: Admins can read messages (same as current E2EE with admin key)

---

Migration Strategy for Existing Messages

Existing v2 (encrypted) messages need handling. Options:

Option A: Decrypt and Convert (Recommended)

Run a one-time migration to decrypt all v2 messages using admin key and store as v1 plaintext.

• Pros: Clean slate, no legacy code needed
• Cons: Requires admin private key, one-time effort

Option B: Leave v2 Messages As-Is

Keep encrypted messages in database but stop creating new ones. Old messages become unreadable.

• Pros: Simpler migration
• Cons: Users lose access to old messages

Option C: Hybrid Display

Keep decryption code for reading old v2 messages, but send new messages as v1.

• Pros: No data loss
• Cons: Maintains complexity, defeats purpose of removal

Recommendation: Option A - decrypt existing messages during migration window.

---

Tasks

Phase 1: Database Migration (Estimated: 2-3 hours)

Task 1.1: Create Migration to Decrypt Existing v2 Messages

Create an edge function that:

1. Fetches all messages with version = 2
2. Decrypts each using admin private key
3. Updates to version = 1, moves decrypted content to content column
4. Clears encrypted_content, encryption_iv, keys_metadata

Files to create:

• apps/supabase/functions/migrate-e2ee-to-plaintext/index.ts

Task 1.2: Run Migration

Execute the migration function against both non-prod and prod databases.

Task 1.3: Verify Migration

Query to confirm no v2 messages remain:

SELECT COUNT(*) FROM messages WHERE version = 2;

---

Phase 2: Remove Client-Side Encryption Code (Estimated: 4-6 hours)

Task 2.1: Remove Encryption Library

Delete the entire encryption directory:

• apps/mobile/src/lib/encryption/ (14 files)

Files to delete:

• adminKeys.ts
• constants.ts
• crypto.ts
• index.ts
• keyManager.ts
• mediaDecryption.ts
• mediaEncryption.ts
• messageDecryption.ts
• messageEncryption.ts
• reencryptPendingMessages.ts
• repairStaleKey.ts
• triggerKeyRotation.ts
• types.ts

Task 2.2: Remove Encryption Hooks

Delete the E2EE-specific hooks:

Files to delete:

• apps/mobile/src/hooks/useDecryptedMessage.ts
• apps/mobile/src/hooks/useDecryptedMedia.ts
• apps/mobile/src/hooks/useEncryptedSend.ts

Task 2.3: Simplify useEncryptionKeys Hook

Either delete entirely or convert to a no-op stub that returns { hasKeys: true } for compatibility.

File to modify/delete:

• apps/mobile/src/hooks/useEncryptionKeys.ts

Task 2.4: Remove EncryptionKeyInitializer Component

Delete the component that initializes E2EE keys on app startup.

File to delete:

• apps/mobile/src/components/EncryptionKeyInitializer.tsx

Task 2.5: Remove from App Layout

Remove EncryptionKeyInitializer from the app layout.

File to modify:

• apps/mobile/app/(app)/_layout.tsx

---

Phase 3: Simplify Chat Components (Estimated: 3-4 hours)

Task 3.1: Simplify ChatScreen.tsx

Remove:

• useEncryptedSend hook usage
• encryptionKeys from store
• secureReady checks
• Recovery UI (encryptionKeys.isRecovering)
• Encryption readiness blocking

Change message sending to use plaintext directly.

File to modify:

• apps/mobile/src/features/chat/ChatScreen.tsx

Task 3.2: Simplify MessageContent.tsx

Remove:

• useDecryptedMessage hook usage
• useDecryptedMedia hook usage
• Decryption loading states
• Decryption error states and retry buttons

Display message.content directly.

File to modify:

• apps/mobile/src/features/chat/MessageContent.tsx

Task 3.3: Simplify Media Upload

Remove encryption from media upload flow.

File to modify:

• apps/mobile/src/hooks/useMediaUpload.ts

Changes:

• Remove encryptMediaFile call
• Upload files directly without .enc extension
• Remove E2EE readiness checks

Task 3.4: Simplify InputBar (if applicable)

Remove any "security not ready" blocking logic.

File to modify:

• apps/mobile/src/features/chat/InputBar.tsx

---

Phase 4: Clean Up State Management (Estimated: 1-2 hours)

Task 4.1: Remove encryptionKeys from Auth Store

Remove the entire encryptionKeys state object and related actions.

File to modify:

• apps/mobile/src/store/authStore.ts

Remove:

• EncryptionKeyState interface
• encryptionKeys state
• setEncryptionKeys action
• beginEncryptionRecovery / endEncryptionRecovery actions
• Reset logic in logout

---

Phase 5: Remove Edge Functions (Estimated: 1 hour)

Task 5.1: Delete E2EE Edge Functions

Remove the edge functions that handle key rotation and re-encryption.

Files to delete:

• apps/supabase/functions/handle-key-rotation/
• apps/supabase/functions/reencrypt-pending-messages/

Task 5.2: Remove from Supabase Dashboard

If deployed, remove these functions from Supabase dashboard or let them remain (they won't be called).

---

Phase 6: Database Cleanup (Optional) (Estimated: 1 hour)

Task 6.1: Remove E2EE Columns (Optional)

Create migration to drop unused columns. Can be deferred.

-- Optional cleanup migration
ALTER TABLE messages
  DROP COLUMN IF EXISTS encrypted_content,
  DROP COLUMN IF EXISTS encryption_iv,
  DROP COLUMN IF EXISTS keys_metadata;

ALTER TABLE messages
  DROP CONSTRAINT IF EXISTS messages_e2ee_fields_check;

ALTER TABLE profiles
  DROP COLUMN IF EXISTS public_key_jwk;

DROP TABLE IF EXISTS master_keys;

Note: Can leave columns in place - they'll just be NULL for new messages.

Task 6.2: Update Message Version Default

Ensure new messages use version 1 (or remove version concept entirely).

---

Phase 7: Cleanup and Testing (Estimated: 2-3 hours)

Task 7.1: Remove Unused Dependencies

Check if react-native-quick-crypto can be removed (may be needed for other crypto).

File to modify:

• apps/mobile/package.json

Task 7.2: Update CLAUDE.md

Remove E2EE documentation section.

File to modify:

• CLAUDE.md

Task 7.3: Delete E2EE Documentation

Remove the E2EE implementation docs.

File to delete:

• docs/e2ee-implementation.md

Task 7.4: Update iOS Permission Strings

Remove "encrypted" from iOS permission descriptions. These strings mention encryption:

File to modify:

• apps/mobile/app.json

Current strings (lines 26-27):

"NSCameraUsageDescription": "Sauci uses your camera to take photos and videos that you can share privately with your partner in encrypted chat messages.",
"NSPhotoLibraryUsageDescription": "Sauci uses your photo library so you can select photos and videos to share privately with your partner in encrypted chat messages.",

Updated strings:

"NSCameraUsageDescription": "Sauci uses your camera to take photos and videos that you can share privately with your partner.",
"NSPhotoLibraryUsageDescription": "Sauci uses your photo library so you can select photos and videos to share privately with your partner.",

After updating app.json, run npx expo prebuild --clean to regenerate ios/Sauci/Info.plist.

Task 7.5: Full Testing

Test all chat functionality:

• Send text message
• Receive text message
• Send image
• Receive image
• Send video
• Receive video
• View old messages (post-migration)
• New user signup and chat
• Device change / reinstall

---

File Summary

Files to Delete (19 files)

apps/mobile/src/lib/encryption/adminKeys.ts
apps/mobile/src/lib/encryption/constants.ts
apps/mobile/src/lib/encryption/crypto.ts
apps/mobile/src/lib/encryption/index.ts
apps/mobile/src/lib/encryption/keyManager.ts
apps/mobile/src/lib/encryption/mediaDecryption.ts
apps/mobile/src/lib/encryption/mediaEncryption.ts
apps/mobile/src/lib/encryption/messageDecryption.ts
apps/mobile/src/lib/encryption/messageEncryption.ts
apps/mobile/src/lib/encryption/reencryptPendingMessages.ts
apps/mobile/src/lib/encryption/repairStaleKey.ts
apps/mobile/src/lib/encryption/triggerKeyRotation.ts
apps/mobile/src/lib/encryption/types.ts
apps/mobile/src/hooks/useDecryptedMessage.ts
apps/mobile/src/hooks/useDecryptedMedia.ts
apps/mobile/src/hooks/useEncryptedSend.ts
apps/mobile/src/hooks/useEncryptionKeys.ts
apps/mobile/src/components/EncryptionKeyInitializer.tsx
docs/e2ee-implementation.md

Files to Modify (8 files)

apps/mobile/src/features/chat/ChatScreen.tsx
apps/mobile/src/features/chat/MessageContent.tsx
apps/mobile/src/features/chat/InputBar.tsx
apps/mobile/src/hooks/useMediaUpload.ts
apps/mobile/src/store/authStore.ts
apps/mobile/app/(app)/_layout.tsx
apps/mobile/app.json
CLAUDE.md

Edge Functions to Delete (2 functions)

apps/supabase/functions/handle-key-rotation/
apps/supabase/functions/reencrypt-pending-messages/

---

Estimated Total Effort

Phase	Estimated Time
Phase 1: Database Migration	2-3 hours
Phase 2: Remove Encryption Code	4-6 hours
Phase 3: Simplify Chat Components	3-4 hours
Phase 4: Clean Up State	1-2 hours
Phase 5: Remove Edge Functions	1 hour
Phase 6: Database Cleanup	1 hour (optional)
Phase 7: Testing	2-3 hours
Total	14-20 hours

---

Rollback Plan

If issues arise after deployment:

1. Messages are preserved - Content column still has plaintext for v1, migration preserves decrypted content
2. Re-enable E2EE - Git revert the client changes
3. No data loss - The migration only adds data (decrypts), doesn't delete

---

Open Questions

1. Timeline: When to execute the migration? During maintenance window?
2. Notification: Should users be notified about the security model change?
3. Privacy Policy: Does the privacy policy mention E2EE? May need update.
4. App Store: Any App Store claims about E2EE that need updating?