public virtual void Init(
bool forEncryption,
ICipherParameters parameters)
{
this.forEncryption = forEncryption;
KeyParameter keyParam;
if (parameters is AeadParameters)
{
AeadParameters param = (AeadParameters)parameters;
nonce = param.GetNonce();
initialAssociatedText = param.GetAssociatedText();
keyParam = param.Key;
}
else if (parameters is ParametersWithIV)
{
ParametersWithIV param = (ParametersWithIV)parameters;
nonce = param.GetIV();
initialAssociatedText = null;
keyParam = (KeyParameter)param.Parameters;
}
else
{
throw new ArgumentException("invalid parameters passed to ChaCha20Poly1305");
}
if (nonce == null || nonce.Length < 1)
{
throw new ArgumentException("IV must be at least 1 byte");
}
// Geneate the key
ChaChaX tmpCypher = new ChaChaX();
byte[] zero = new byte[32];
byte[] polyKey = new byte[32];
ParametersWithIV tmpKey = new ParametersWithIV(keyParam, nonce);
tmpCypher.Init(true, tmpKey);
tmpCypher.ProcessBytes(zero, 0, zero.Length, polyKey, 0);
poly = new Poly1305();
KeyParameter tmpKey2 = new KeyParameter(polyKey);
poly.Init(tmpKey2);
chacha20 = new ChaChaX();
chacha20.Init(forEncryption, tmpKey);
InitCipher();
}
