using Lucinda; // Create an E2EE instance using var e2ee = new EndToEndEncryption(); // Generate key pairs for Alice and Bob var aliceKeyPair = e2ee.GenerateKeyPair(); var bobKeyPair = e2ee.GenerateKeyPair(); // Alice encrypts a message for Bob var encrypted = e2ee.EncryptMessage("Hello, Bob!", bobKeyPair.Value.PublicKey); // Bob decrypts the message var decrypted = e2ee.DecryptMessage(encrypted.Value, bobKeyPair.Value.PrivateKey); Console.WriteLine(decrypted.Value); // "Hello, Bob!"

using Lucinda; // Alice and Bob setup using var alice = new SecureMessaging(); using var bob = new SecureMessaging(); alice.GenerateIdentityKeyPair(); bob.GenerateIdentityKeyPair(); bob.GeneratePreKeyBundle(); // Alice initiates session with Bob's pre-key bundle var bobBundle = bob.GetPublicPreKeyBundle(); alice.InitializeSession("bob", bobBundle.Value); // Bob creates session from Alice's initial contact var initialMessage = alice.GetInitialMessageData("bob"); bob.CreateSessionFromInitialMessage("alice", initialMessage.Value); // Send encrypted messages with forward secrecy var encrypted = alice.SendMessage("bob", "Hello with forward secrecy!"); var decrypted = bob.ReceiveMessage("alice", encrypted.Value); Console.WriteLine(decrypted.Value); // "Hello with forward secrecy!"

using Lucinda.Protocol.SenderKeys; // Create group sessions for each participant using var alice = new GroupSession("my-group-123", "alice"); using var bob = new GroupSession("my-group-123", "bob"); using var charlie = new GroupSession("my-group-123", "charlie"); // Initialize sender keys alice.Initialize(); bob.Initialize(); charlie.Initialize(); // Exchange distribution messages (each participant shares their sender key) var aliceDist = alice.CreateDistributionMessage(); var bobDist = bob.CreateDistributionMessage(); alice.ProcessDistributionMessage("bob", bobDist.Value); bob.ProcessDistributionMessage("alice", aliceDist.Value); // Alice sends encrypted message to the group (single encryption for all recipients) var groupMessage = alice.Encrypt(Encoding.UTF8.GetBytes("Hello group!")); // Bob decrypts the group message var decrypted = bob.Decrypt(groupMessage.Value); Console.WriteLine(Encoding.UTF8.GetString(decrypted.Value)); // "Hello group!"

using Lucinda.Symmetric; // Generate a new key using var aes = new AesGcmEncryption(256); // 256-bit key // Encrypt data var plaintext = "Sensitive data"u8.ToArray(); var encrypted = aes.Encrypt(plaintext); // Decrypt data var decrypted = aes.Decrypt(encrypted.Value); // With associated data (AAD) var metadata = "header"u8.ToArray(); var encryptedWithAad = aes.Encrypt(plaintext, metadata); var decryptedWithAad = aes.Decrypt(encryptedWithAad.Value, metadata);

using Lucinda.Asymmetric; using var hybrid = new RsaAesHybridEncryption(); // Generate a key pair var keyPair = hybrid.GenerateKeyPair(); // Encrypt (anyone with the public key can encrypt) var data = "Large amount of data..."u8.ToArray(); var encrypted = hybrid.Encrypt(data, keyPair.Value.PublicKey); // Decrypt (only the private key holder can decrypt) var decrypted = hybrid.Decrypt(encrypted.Value, keyPair.Value.PrivateKey);

using Lucinda.Signatures; // ECDSA signatures using var signer = new EcdsaSignature(); var keyPair = signer.GenerateKeyPair(); var data = "Data to sign"u8.ToArray(); // Sign var signature = signer.Sign(data); // Verify var isValid = signer.Verify(data, signature.Value); Console.WriteLine(isValid.Value); // true

using Lucinda.KeyDerivation; using var pbkdf2 = new Pbkdf2KeyDerivation(); // Derive a key from a password var password = "MySecretPassword"; var salt = SecureRandom.GenerateSalt(32); var derivedKey = pbkdf2.DeriveKey(password, salt, iterations: 600000, derivedKeyLength: 32); // Use derivedKey.Value for encryption

using Lucinda.KeyDerivation; using var hkdf = new HkdfKeyDerivation(); // Derive keys from a shared secret var sharedSecret = new byte[32]; // From key exchange var salt = SecureRandom.GenerateSalt(32); var info = "encryption-key"u8.ToArray(); var encryptionKey = hkdf.DeriveKey(sharedSecret, salt, info, 32);

using Lucinda.KeyExchange; // Alice generates her key pair using var aliceEcdh = new EcdhKeyExchange(); var alicePublicKey = aliceEcdh.GetPublicKey(); // Bob generates his key pair using var bobEcdh = new EcdhKeyExchange(); var bobPublicKey = bobEcdh.GetPublicKey(); // Both derive the same shared secret var aliceSharedSecret = aliceEcdh.DeriveSharedSecret(bobPublicKey.Value); var bobSharedSecret = bobEcdh.DeriveSharedSecret(alicePublicKey.Value); // aliceSharedSecret == bobSharedSecret

using Lucinda; using var e2ee = new EndToEndEncryption(); // Generate keys var senderSigningKeyPair = e2ee.GenerateSigningKeyPair(); var recipientKeyPair = e2ee.GenerateKeyPair(); var message = "Authenticated and encrypted message"u8.ToArray(); // Encrypt and sign var signedEncrypted = e2ee.EncryptAndSign( message, recipientKeyPair.Value.PublicKey, senderSigningKeyPair.Value.PrivateKey); // Verify and decrypt var decrypted = e2ee.VerifyAndDecrypt( signedEncrypted.Value, recipientKeyPair.Value.PrivateKey, senderSigningKeyPair.Value.PublicKey); if (decrypted.IsSuccess) { Console.WriteLine("Message verified and decrypted!"); }

var result = aes.Encrypt(data); if (result.IsSuccess) { var encrypted = result.Value; // Use encrypted data } else { Console.WriteLine($"Error: {result.Error}"); } // Or use pattern matching result.Match( onSuccess: data => ProcessData(data), onFailure: error => HandleError(error) );