/// <summary>
/// Encrypts some data with some key under the use of a nonce and prepends the ciphertext with the nonce
/// </summary>
/// <returns>The data.</returns>
/// <param name="data">Data.</param>
/// <param name="key">Key.</param>
/// <param name="nonce">Nonce.</param>
public static byte[] EncryptData(byte[] data, byte[] key, byte[] nonce = null)
{
long cipherTextLength = data.Length + 16;
byte[] cipherText = new byte[cipherTextLength];
if (nonce == null)
{
nonce = StreamEncryption.GetRandomBytes(X_NONC_ESIZE);
}
int result = NativeLibsodium.crypto_aead_xchacha20poly1305_ietf_encrypt(
cipherText,
out cipherTextLength,
data,
data.Length,
null, 0, null,
nonce,
key);
if (result != 0)
{
throw new Exception("Encryption error");
}
byte[] cipherTextWithNonce = IEncryption.ConcatBytes(nonce, cipherText);
return(cipherTextWithNonce);
}
/// <summary>
/// Encrypts data with the current session key.
/// </summary>
/// <returns>The encrypted data.</returns>
/// <param name="message">Data to encrypt.</param>
public byte[] EncryptWithSessionKey(byte[] message)
{
byte[] nonce = IEncryption.ConcatBytes(StreamEncryption.GetRandomBytes(X_NONC_ESIZE - 16), BitConverter.GetBytes(DateTime.UtcNow.Ticks), BitConverter.GetBytes(sessionSendKey.index));
byte[] cipherTextWithNonce = EncryptData(message, GetCurrentSendKey(), nonce);
// ratchat forward
RatchetSendKey();
return(cipherTextWithNonce);
}
public override void Execute(CommandData data)
{
var returnData = ExecuteWithReturn(data);
// set headers
returnData.Type = "response";
returnData.Recipient = data.SenderId;
returnData.SenderId = data.Recipient;
// wrap it into a container so receiver knows to what request it coresponds to
returnData.message = IEncryption.ConcatBytes(BitConverter.GetBytes(data.MessageId), returnData.message);
data.SendBack(returnData);
//SendTo(data.sId, user.PublicId, "createdUser");
}
/// <summary>
/// Derives session keys from four key pairs and stores them in intern variables.
/// </summary>
/// <returns>Void.</returns>
/// <param name="ePPK">E PP.</param>
/// <param name="ePK">E P.</param>
/// <param name="iPK">I P.</param>
/// <param name="ePOTK">E POT.</param>
private void DeriveSessionKeys(KeyPair ePPK, KeyPair ePK, KeyPair iPK, KeyPair ePOTK)
{
sessionReceiveKey.key = LibsodiumEncryption.Hash(IEncryption.ConcatBytes(ePPK.secretKey, ePK.secretKey, iPK.secretKey, ePOTK.secretKey));
sessionSendKey.key = LibsodiumEncryption.Hash(IEncryption.ConcatBytes(ePPK.publicKey, ePK.publicKey, iPK.publicKey, ePOTK.publicKey));
/*
* NotificationHandler.Instance.ShowNotification("",
* "sessionReceiveKey is : " + Convert.ToBase64String(sessionReceiveKey) +
* " sessionSendKey is : " + Convert.ToBase64String(sessionSendKey) +
* " ePPK s is : " + Convert.ToBase64String(ePPK.secretKey) +
* " ePK s is : " + Convert.ToBase64String(ePK.secretKey) +
* " iPK s is : " + Convert.ToBase64String(iPK.secretKey) +
* " ePOTK s is : " + Convert.ToBase64String(ePOTK.secretKey) +
* " ePPK is : " + Convert.ToBase64String(ePPK.publicKey) +
* " ePK is : " + Convert.ToBase64String(ePK.publicKey) +
* " iPK is : " + Convert.ToBase64String(iPK.publicKey) +
* " ePOTK is : " + Convert.ToBase64String(ePOTK.publicKey));*/
}
/// <summary>
/// Advances the key.
/// </summary>
/// <returns>The key.</returns>
/// <param name="key">Key.</param>
public static byte[] AdvanceKey(byte[] key)
{
return(LibsodiumEncryption.Hash(IEncryption.ConcatBytes(key, new byte[] { 0x02 })));
}
/// <summary>
/// Gets the enc key from the chainkey.
/// Does this by appending 0x01 to and hashing the current key
/// </summary>
/// <returns>The enc key from chain.</returns>
/// <param name="chainKey">Chain key.</param>
public static byte[] GetEncKeyFromChain(ChainKey chainKey)
{
return(LibsodiumEncryption.Hash(IEncryption.ConcatBytes(chainKey.key, new byte[] { 0x01 })));
}
/// <summary>
/// Converts a chain key to an Encryption key for actual usage
/// </summary>
/// <returns>The encryption key.</returns>
/// <param name="chainKey">Chain key.</param>
private byte[] ChainToEncryptionKey(byte[] chainKey)
{
return(LibsodiumEncryption.Hash(IEncryption.ConcatBytes(chainKey, new byte[] { 0x01 })));
}
