ffr_crypto 0.0.3

A Flutter-first, Rust-powered native cryptography package supporting RSA, AES-GCM, ChaCha20-Poly1305, SHA-2/3, BLAKE3, KDFs (Argon2), Ed25519, X25519, and ECIES.

ffr_crypto

A Flutter-first, Rust-powered native cryptography package using Dart FFI and Flutter Native Assets.

Features

• Secure Random: CSPRNG random byte generation.
• Asymmetric Cryptography:
  • RSA-OAEP encryption/decryption (2048, 3072, 4096-bit).
  • RSA-PSS signatures (signing/verification).
• Symmetric Cryptography:
  • AES-GCM (128 & 256-bit keys) with AAD.
  • ChaCha20-Poly1305 with AAD.
• Hashing: SHA-2 (SHA-256, SHA-512), SHA-3 (SHA3-256, SHA3-512), and BLAKE3 with one-shot and stateful streaming APIs.
• Key Derivation (KDF): PBKDF2-HMAC-SHA-256, HKDF-SHA-256, and Argon2 (id, i, d).
• Elliptic Curve Cryptography (ECC): Ed25519 signatures and X25519 Diffie-Hellman key exchange.
• Hybrid Encryption (ECIES): Composed hybrid encryption using X25519, HKDF-SHA-256, and ChaCha20-Poly1305.

Performance & Design

• Off-Thread Processing: All computationally expensive operations (RSA, KDFs, Hybrid, Signatures) run asynchronously on background Dart Isolates (Isolate.run), preventing UI frames from dropping.
• Native Assets Pipeline: Uses modern Flutter native assets build hooks (hook/build.dart) to compile the underlying Rust library automatically.
• Robust Error Handling: Translates C-ABI status codes into clear, typed CryptoException subclasses.

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Platform Support

ffr_crypto compiles a native Rust library at build time via Flutter Native Assets. It works on all platforms where a Rust toolchain is available.

Platform	Architectures	Supported
🍎 macOS	arm64, x64	✅
📱 iOS	arm64, x64 (simulator)	✅
🤖 Android	arm64-v8a, armeabi-v7a, x86, x86_64	✅
🐧 Linux	arm64, x64	✅
🪟 Windows	x64	✅
🌐 Web	—	❌ (dart:ffi is unsupported on Web)

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Getting Started

Add the package dependency to your pubspec.yaml:

dependencies:
  ffr_crypto: ^0.0.1

Prerequisites — Rust Toolchain

Install the Rust toolchain first, then add the targets for each platform you intend to build:

# macOS (Apple Silicon + Intel)
rustup target add aarch64-apple-darwin x86_64-apple-darwin

# iOS (Device + Simulator)
rustup target add aarch64-apple-ios x86_64-apple-ios

# Android (requires NDK via Android Studio or sdkmanager)
rustup target add aarch64-linux-android armv7-linux-androideabi \
                   i686-linux-android x86_64-linux-android

# Linux
rustup target add aarch64-unknown-linux-gnu x86_64-unknown-linux-gnu

# Windows (run on a Windows host)
rustup target add x86_64-pc-windows-msvc

Note: Android builds additionally require the Android NDK. Install it via Android Studio → SDK Manager → SDK Tools → NDK.

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API Usage Examples

1. Cryptographically Secure Random Bytes

import 'package:ffr_crypto/ffr_crypto.dart';

Uint8List bytes = await Random.secureBytes(32);

2. Hashing (One-shot & Streaming)

import 'package:ffr_crypto/ffr_crypto.dart';

// One-shot
Uint8List sha256Digest = await Hash.hash(HashAlgorithm.sha256, bytes);

// Incremental/Streaming
final hasher = await Hasher.create(HashAlgorithm.blake3);
await hasher.update(chunk1);
await hasher.update(chunk2);
Uint8List blake3Digest = await hasher.finalize(); // Context is automatically freed

3. Symmetric Encryption (AES-GCM)

import 'package:ffr_crypto/ffr_crypto.dart';

Uint8List ciphertext = await AesGcm.encrypt(
  key: key256,
  plaintext: plaintext,
  nonce: nonce12,
  aad: optionalAad,
);

Uint8List decrypted = await AesGcm.decrypt(
  key: key256,
  ciphertext: ciphertext,
  nonce: nonce12,
  aad: optionalAad,
);

4. Asymmetric Cryptography (RSA-OAEP & RSA-PSS)

import 'package:ffr_crypto/ffr_crypto.dart';

// Generate key pair
RsaKeyPair pair = await RsaKeyPair.generate(2048);

// Encrypt & Decrypt
Uint8List ciphertext = await Rsa.encrypt(pair.publicKey, plaintext);
Uint8List decrypted = await Rsa.decrypt(pair.privateKey, ciphertext);

// Sign & Verify
Uint8List sig = await Rsa.sign(pair.privateKey, digest);
bool verified = await Rsa.verify(pair.publicKey, digest, sig);

5. Elliptic Curve Cryptography (ECC)

import 'package:ffr_crypto/ffr_crypto.dart';

// Ed25519 Sign/Verify
final edPair = await Ed25519.generateKeyPair();
final sig = await Ed25519.sign(privateKey: edPair.privateKey, message: msg);
final isValid = await Ed25519.verify(publicKey: edPair.publicKey, message: msg, signature: sig);

// X25519 Key Exchange
final alice = await X25519.generateKeyPair();
final bob = await X25519.generateKeyPair();
final secretAlice = await X25519.computeSharedSecret(privateKey: alice.privateKey, peerPublicKey: bob.publicKey);

6. Hybrid Encryption (ECIES)

import 'package:ffr_crypto/ffr_crypto.dart';

// Encrypt payload for recipient using their public key
Uint8List payload = await HybridEncryption.encrypt(
  recipientPublicKey: recipientPublicKey,
  plaintext: plaintext,
);

// Recipient decrypts payload using their private key
Uint8List decrypted = await HybridEncryption.decrypt(
  recipientPrivateKey: recipientPrivateKey,
  payload: payload,
);