Introduction

bmoni_embedded_sdk — on-device Ethereum wallet provisioning and signing for React Native.

bmoni_embedded_sdk is a React Native library that exposes the BMONISigner native SDKs for Android and iOS. It lets you provision a self-custodied secp256k1 wallet and produce EIP-191 / EIP-712 compatible signatures entirely within the device’s secure hardware boundary.

It is a port of the Flutter plugin of the same name, and keeps the same API surface, PIN policy, and error codes. The npm package and the pub.dev package are both called bmoni_embedded_sdk.

Security first. Private keys are generated on-device, encrypted with a platform-managed wrapping key (Android Keystore on Android, Secure Enclave on iOS), and persisted only as ciphertext. Plaintext keys never leave the secure boundary and are zeroized in RAM after each operation.

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What it does

Capability	API
Provision a wallet	initWallet()
Read the cached address	walletAddress(), hasWallet()
Delete the wallet	deleteWallet(pin?)
Set / change / remove PIN	setPin, changePin, removePin, matchPin, hasPin
Sign a personal message (EIP-191)	signMessage(message, pin?)
Sign a 32-byte hash	signTransactionHash(hashHex, pin?)
Configure PIN policy	BmoniEmbeddedSdk.initialize({ pinLength, requirePin })

All signatures are returned as 0x-prefixed 130-character hex strings in recoverable r(32) ‖ s(32) ‖ v(1) format with v ∈ {27, 28} and low-s normalisation (EIP-2 compliant), ready to be verified server-side with ecrecover.

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Platform support

Android	iOS
✅ Android Keystore (minSdk 24+)	✅ Secure Enclave (iOS 15.1+)

The library ships a TurboModule, so it requires the New Architecture — the default since React Native 0.76.

The BMONISigner Android AAR ships an arm64-v8a slice only. Build for arm64-v8a and run on an arm64 device or emulator, or the native library fails to load at runtime. See installation.

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Architecture

BmoniEmbeddedSdk is a static facade — you never instantiate it. Every method is static and can be called from anywhere after a single initialize call.

BmoniEmbeddedSdk (TypeScript facade)
        │
        ├── PIN layer (platform secure storage + PBKDF2-HMAC-SHA256)
        │
        └── TurboModule ──► BMONISigner (native)
                                 ├── Android Keystore
                                 └── iOS Secure Enclave

The TypeScript layer adds:

• Address caching — the initWallet() result is persisted in platform secure storage, so you can read it back after the app restarts without re-provisioning.
• PIN gating — when requirePin is true, the PIN digest is verified in TypeScript before forwarding to the native module.

Secure storage and the key derivation are provided by the native module itself (Android Keystore-wrapped preferences and the iOS Keychain), so the library adds no peer dependencies beyond react-native.

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Differences from the Flutter SDK

The API is the same, with the adjustments you would expect from moving to TypeScript:

Flutter	React Native
BmoniEmbeddedSdk.initialize(pinLength: 6, requirePin: true)	BmoniEmbeddedSdk.initialize({ pinLength: 6, requirePin: true })
signMessage(msg, pin: '123456')	signMessage(msg, '123456')
changePin(currentPin: a, newPin: b)	changePin({ currentPin: a, newPin: b })
BmoniSignerException	BmoniSignerError (extends Error)
on BmoniSignerException catch (e)	if (error instanceof BmoniSignerError)

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Links

• npm package page
• GitHub repository
• Next: Installation