[mob] Add crypto abstraction layer (ente_crypto_api)

[neeraj-pilot]

Summary

Introduce a crypto abstraction layer to allow swapping implementations without changing consumer code. This enables future support for different crypto backends (Rust FFI, platform plugins, etc).

Changes

• Add ente_crypto_api package with CryptoApi interface and CryptoUtil façade
• Add ente_crypto_dart_adapter wrapping existing ente_crypto_dart
• Update all packages/apps to use the new abstraction
• Register adapter at app startup before any crypto operations

Architecture

┌─────────────────────────────────────────────────────────────────────────────────────┐
│                                    APPLICATIONS                                      │
├─────────────────────┬─────────────────────┬─────────────────────────────────────────┤
│     apps/auth       │    apps/locker      │              apps/photos                │
│                     │                     │                                         │
│  main.dart:         │  main.dart:         │  main.dart:                             │
│  registerCryptoApi( │  registerCryptoApi( │  registerCryptoApi(                     │
│    EnteCryptoDart   │    EnteCryptoDart   │    EntePhotosPluginAdapter() // future  │
│    Adapter()        │    Adapter()        │  )                                      │
│  )                  │  )                  │                                         │
└─────────┬───────────┴─────────┬───────────┴──────────────────┬──────────────────────┘
          │                     │                              │
          │ depends on          │ depends on                   │ depends on
          ▼                     ▼                              ▼
┌─────────────────────────────────────────────────────────────────────────────────────┐
│                              ADAPTER LAYER                                           │
├────────────────────────────────┬────────────────────────────┬───────────────────────┤
│  ente_crypto_dart_adapter      │  ente_crypto_rust_adapter  │ ente_photos_plugin    │
│  (CURRENT)                     │  (FUTURE)                  │ _adapter (FUTURE)     │
│                                │                            │                       │
│  class EnteCryptoDartAdapter   │  class EnteCryptoRust      │ class EntePhotos      │
│    implements CryptoApi {      │    Adapter                 │   PluginAdapter       │
│    ...                         │    implements CryptoApi {  │   implements CryptoApi│
│  }                             │    // FFI to Rust          │ {                     │
│                                │  }                         │   // calls plugin     │
│         │                      │         │                  │ }                     │
│         │ wraps                │         │ wraps            │         │ wraps       │
│         ▼                      │         ▼                  │         ▼             │
│  ┌──────────────────┐          │  ┌──────────────────┐      │  ┌──────────────────┐ │
│  │ ente_crypto_dart │          │  │ ente_crypto_rs   │      │  │ photos/plugins/  │ │
│  │ (git dependency) │          │  │ (native lib)     │      │  │ crypto           │ │
│  └──────────────────┘          │  └──────────────────┘      │  └──────────────────┘ │
└────────────────────────────────┴────────────────────────────┴───────────────────────┘
          │                                │                              │
          │ implements                     │ implements                   │ implements
          └────────────────────────────────┼──────────────────────────────┘
                                           ▼
┌─────────────────────────────────────────────────────────────────────────────────────┐
│                              API LAYER (INTERFACE)                                   │
│                                                                                      │
│                               ente_crypto_api                                        │
│  ┌────────────────────────────────────────────────────────────────────────────────┐ │
│  │  abstract class CryptoApi { ... }                                              │ │
│  │  void registerCryptoApi(CryptoApi impl);   ◄── called once at app startup      │ │
│  │  class CryptoUtil { ... }                  ◄── static façade for consumers     │ │
│  └────────────────────────────────────────────────────────────────────────────────┘ │
│                                                                                      │
│  Models: EncryptionResult, FileEncryptResult, DerivedKeyResult, CryptoKeyPair        │
└─────────────────────────────────────────────────────────────────────────────────────┘
                                           ▲
                                           │ depends on (interface only)
                                           │
┌─────────────────────────────────────────────────────────────────────────────────────┐
│                              SHARED PACKAGES                                         │
│  accounts, configuration, lock_screen, sharing, legacy                               │
│  (import ente_crypto_api, call CryptoUtil.*, no knowledge of adapter)               │
└─────────────────────────────────────────────────────────────────────────────────────┘

Adding a New Adapter

To add a new adapter (e.g., Rust FFI):

1. Create package implementing CryptoApi
2. Change app's main.dart to register the new adapter
3. No changes needed in shared packages

[chatgpt-codex-connector]

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Reviewed commit: fefd6306df

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[chatgpt-codex-connector]

Replace cryptoPwHash/sodium usage after API switch

After switching this file to ente_crypto_api, it still calls the old top-level cryptoPwHash and sodium symbols inside confirmPinAuth. Those symbols are not exported by the new package, so the lock_screen package will fail to compile with undefined identifiers unless the call is migrated to CryptoUtil.cryptoPwHash and the CryptoUtil.pwhash* getters.

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[chatgpt-codex-connector]

Rename encryptFileWithMD5 call to new API

This file now imports ente_crypto_api, but later invokes CryptoUtil.encryptFileWithMD5. The new API only exposes encryptFileWithMd5, so the locker app will not compile after this change; rename the call (or add a compatibility wrapper) to keep uploads building.

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[AmanRajSinghMourya]

Found a couple of issues that need fixing:

1. mobile/apps/locker/lib/services/files/upload/file_upload_service.dart:340
Method name mismatch - encryptFileWithMD5 should be encryptFileWithMd5 (lowercase 'd5')

2. mobile/packages/ente_crypto_api/lib/src/crypto_api.dart

• Line 4: Unused import package:meta/meta.dart - remove it
• Line 6: Unused import errors.dart - remove it
• Lines 7-9: Use package:ente_crypto_api/... imports instead of relative imports

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: d5ea90862b

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[chatgpt-codex-connector]

Use distinct prefixes for dart_models imports

Dart does not allow the same import prefix to be assigned to multiple libraries. Here both derived_key_result.dart and encryption_result.dart are imported as dart_models, which triggers a compile-time error (“prefix 'dart_models' is already defined”). As a result, any app depending on ente_crypto_dart_adapter (e.g., auth/locker) will fail to build. Rename one prefix or drop the unused import.

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