Description

react-native-fast-crypto@2.2.0 ships a prebuilt libsecp256k1.so (4 KB-aligned) inside its package's android/jni/libs/<ABI>/ directory. Google Play flagged this .so as non-compliant with Android's 16 KB page-size requirement on the x86_64 ABI. As a workaround, #30590 drops the x86_64 ABI from production AABs entirely, but the same .so still ships for arm64-v8a with 4 KB alignment — which will eventually trigger the same Play warning on arm64, and is already non-compliant for Android 15+ devices running in 16 KB mode.

We only consume scrypt from react-native-fast-crypto:

// app/core/Engine/controllers/identity/user-storage-controller-init.ts
import { scrypt } from 'react-native-fast-crypto';
// ...
nativeScryptCrypto: scrypt,

react-native-quick-crypto@1.x (Nitro Modules rewrite) ships a Node-compatible crypto.scrypt(password, salt, keylen[, options], callback) API that uses OpenSSL underneath, is 16 KB-aligned, and is actively maintained by Margelo. We already depend on react-native-quick-crypto@0.7.15 so upgrading consolidates two crypto deps into one.

Technical Details

Scope of change

1. Bump react-native-quick-crypto 0.7.15 → 1.x

   • Requires react-native ≥ 0.75 and New Architecture enabled (✅ we already have newArchEnabled=true).
   • Adds react-native-nitro-modules as a peer dep.
   • Re-evaluate the existing yarn patch (.yarn/patches/react-native-quick-crypto-npm-0.7.15-85c4f4892e.patch) against 1.x — rewrite or drop.

2. Add a fast-crypto-shaped adapter at the single call site (app/core/Engine/controllers/identity/user-storage-controller-init.ts):

   import QuickCrypto from 'react-native-quick-crypto';
   import { Buffer } from '@craftzdog/react-native-buffer';
   
   export const scrypt = (
     passwd: Uint8Array,
     salt: Uint8Array,
     N: number,
     r: number,
     p: number,
     size: number,
   ): Promise<Uint8Array> =>
     new Promise((resolve, reject) =>
       QuickCrypto.scrypt(
         Buffer.from(passwd),
         Buffer.from(salt),
         size,
         { N, r, p, maxmem: 256 * 1024 * 1024 },
         (err, derived) =>
           err ? reject(err) : resolve(new Uint8Array(derived as Buffer)),
       ),
     );

   ⚠️ Watch maxmem: Node's default is 32 MiB, which is too low for profile-sync params (N=2^17, r=8 → ~134 MiB needed). Set explicitly.

3. Add a known-vector test asserting our adapter produces the same bytes as fast-crypto did. Use RFC 7914 §12 vectors plus our actual profile-sync params (N=2^17, r=8, p=1, dkLen=32).

4. Remove the react-native-fast-crypto dependency from package.json and its yarn patch (.yarn/patches/react-native-fast-crypto-npm-2.2.0-57b8a8a01a.patch).

5. Remove the type declaration (app/declarations/index.d.ts line 15: declare module 'react-native-fast-crypto';).

Verification

• Both libraries implement RFC 7914 scrypt → byte-for-byte identical output for the same (password, salt, N, r, p, dkLen).
• After the swap, unzip -l app-prod-release.aab | grep libsecp256k1 should return empty across all ABIs.
• unzip -l app-prod-release.aab | grep libcrypto_bridge (fast-crypto's JNI shim) should also disappear.

Risk

• Low. scrypt is a pure function with no persisted state; if the adapter is correct, there's no migration concern.
• The riskiest piece is the react-native-quick-crypto 0.x → 1.x bump itself, not the scrypt swap. Margelo claims API compatibility in their README.

Acceptance Criteria

• react-native-fast-crypto removed from package.json and .yarn/patches/.
• react-native-quick-crypto bumped to a 1.x version with scrypt support.
• Adapter in place at the user-storage-controller-init scrypt call site.
• Known-vector unit test asserting RFC 7914 §12 outputs are produced.
• Production AAB contains no libsecp256k1.so and no libcrypto_bridge.so under any ABI.
• Profile-sync init time tested on a mid-range Android device — no perceptible regression vs. fast-crypto baseline.
• CHANGELOG entry added (e.g. "Removed react-native-fast-crypto in favor of react-native-quick-crypto scrypt; reduces Android AAB size and improves 16 KB compliance.").

References

• Related PR (workaround that drops x86_64 ABI): fix(android): exclude x86_64 ABI from production AAB to resolve Play 16 KB warning #30590
• Existing yarn patch: .yarn/patches/react-native-fast-crypto-npm-2.2.0-57b8a8a01a.patch — already attempts 16 KB alignment for the compiled bridge code but cannot rebuild the imported libsecp256k1.so.
• Single call site: app/core/Engine/controllers/identity/user-storage-controller-init.ts
• Android 16 KB page sizes: https://developer.android.com/guide/practices/page-sizes
• react-native-quick-crypto 1.x: https://github.com/margelo/react-native-quick-crypto
• scrypt RFC 7914 test vectors: https://www.rfc-editor.org/rfc/rfc7914#section-12