Cipher.swift

Cipher.swift

enum Cipher {
    case root
    case generated(Data)

    func decrypt(data: Data) throws -> Data {
        /// In this case we use simple XOR decryption
        /// In real work implementation we should use AES here
        let _key = Array(key)
        var _data: Data = Data()
        for (offset, element)  in data.enumerated() {
            _data.append(element ^ _key[offset % _key.count])
        }

        return _data
    }
    
    func encrypt(data: Data) throws -> Data {
        /// In this case we use simple XOR encryption
        /// In real work implementation we should use AES here
        let _key = Array(key)
        var _data: Data = Data()
        for (offset, element)  in data.enumerated() {
            _data.append(element ^ _key[offset % _key.count])
        }
        
        return _data
    }

    /// Returns key that should be used for encryption/decryption
    private var key: Data {
        switch self {
        case .generated(let key):
            return key
        case .root:
            return self.rootKey
        }
    }
    
    /// Returns data describing root key
    private var rootKey: Data {
        // generate random 256bit key using `openssl rand -base64 32`
        return Data(base64Encoded: "Ph6jJKFgPp2cnjfZazdvMVCB9whUrpr10Ywat6BlQYQ=")!
    }
}