/// <summary>
/// Creates a symmetric decryptor object with the current Key property and one-time use state parameter.
/// </summary>
/// <param name="key">The secret that will be used during decryption.</param>
/// <param name="nonce">The one-time use state parameter.</param>
public override ICryptoTransform CreateDecryptor(byte[] key, byte[] nonce)
{
var ivLow = m_iv;
var ivHigh = BinaryPrimitives.ReadUInt32LittleEndian(nonce.AsSpan(0, ChaChaTransform.WordLength));
return(ChaChaTransform.New(Initialize(key, nonce, ivLow), BitwiseHelpers.ConcatBits(ivHigh, ivLow), 20U));
}
/// <summary>
/// Creates a symmetric decryptor object with the current Key property and one-time use state parameter.
/// </summary>
/// <param name="key">The secret that will be used during decryption.</param>
/// <param name="nonce">The one-time use state parameter.</param>
public override ICryptoTransform CreateDecryptor(byte[] key, byte[] nonce)
{
var ivLow = ((uint)BitwiseHelpers.ExtractLow(m_iv));
return(ChaChaTransform.New(Initialize(key, nonce, ivLow), m_iv, 20U));
}