AppCrypto

AppCrypto is a Dart class providing various cryptographic functionalities for secure data handling, including encryption, decryption, key derivation, and hashing. This class leverages the pointycastle library for cryptographic operations and utilizes Dart isolates for performing computationally intensive tasks off the main thread.

Features

• File Encryption and Decryption: Encrypt and decrypt files using AES with CBC mode and PKCS7 padding.
• Key Derivation: Derive keys from passwords using PBKDF2 with HMAC and SHA-256.
• HMAC Generation: Generate HMACs using SHA-256.
• Elliptic Curve Cryptography: Generate and encode/decode EC key pairs and derive shared secrets.
• Random Salt Generation: Generate secure random salts for hashing.
• Hashing with Salt: Compute SHA-256 hashes with optional salts.

Installation

Add pointycastle to your pubspec.yaml:

dependencies:
  pointycastle: ^3.1.0

static FileEncryptionService fileEncryptionService(String pin)

static Uint8List generateSaltPRNG()

static Uint8List deriveKey(String input)

static Future<Uint8List> deriveKeyIsolate(String input)

static Uint8List _generateRandomBytes(int length)

static Future<Uint8List> encryptAESInIsolate(Uint8List plaintext, Uint8List key)

static Uint8List encryptAES(Uint8List plaintext, Uint8List key)

static Future<void> decryptFileAES(String inputPath, String outputPath, Uint8List key)

static Future<void> encryptFileAES(String inputPath, String outputPath, Uint8List key)

static Future<Uint8List> generateHMACIsolate(Uint8List key, Uint8List message)

static Future<Uint8List> decryptAESInIsolate(Uint8List bytes, Uint8List sharedKey)

static Uint8List decryptAES(Uint8List ciphertext, Uint8List key)

static AsymmetricKeyPair<ECPublicKey, ECPrivateKey> generateECKeyPair({int bitLength = 2048})

static SecureRandom _secureRandom()

static Uint8List deriveSharedSecret(ECPrivateKey privateKey, ECPublicKey serverPublicKey)

static String encodeECPublicKey(ECPublicKey publicKey)

static ECPublicKey decodeECPublicKey(String base64String)

static Uint8List _bigIntToByteArray(BigInt bigInt)

static Uint8List sha256Digest(Uint8List input, {List? salt})

static Uint8List generateHMAC(Uint8List key, Uint8List message)

static Uint8List hashWithSalt(Uint8List data, Uint8List salt)

static Uint8List generateSalt({int length = 16})

static bool verifyHash(Uint8List input, Uint8List storedHash, Uint8List salt)