/// <summary>
/// Default constructor for Symmetric key algorithm
/// </summary>
/// <param name="algorithm">Algorithm to use</param>
/// <param name="keySizeInBits">Key size in bits, e.g. 256</param>
/// <param name="settings">Settings for chosen algorithm</param>
public SymmetricKeyAlgorithm(SymmetricEncryptionAlgorithm algorithm, int keySizeInBits, object settings)
{
this.algorithm = algorithm.ToString();
if (algorithm == SymmetricEncryptionAlgorithm.AES_CTR)
{
if (!Array.Exists(AES_CTR.allowedKeyLengths, allowed => allowed * 8 == keySizeInBits))
{
throw new ArgumentException($"{keySizeInBits} is not valid AES-CTR key size!");
}
this.settingsAES_CTR = (SettingsAES_CTR)settings;
}
else if (algorithm == SymmetricEncryptionAlgorithm.ChaCha20)
{
if (ChaCha20.allowedKeyLength * 8 != keySizeInBits)
{
throw new ArgumentException($"{keySizeInBits} is not valid ChaCha20 key size!");
}
this.settingsChaCha20 = (SettingsChaCha20)settings;
}
else
{
throw new NotImplementedException($"{algorithm} constructor not implemented yet!");
}
this.keySizeInBits = keySizeInBits;
}
/// <summary>
/// Deep copy constructor
/// </summary>
/// <param name="copyThis">SymmetricKeyAlgorithm to copy</param>
public SymmetricKeyAlgorithm(SymmetricKeyAlgorithm copyThis)
{
this.algorithm = copyThis.algorithm;
this.keySizeInBits = copyThis.keySizeInBits;
if (copyThis.settingsAES_CTR != null)
{
this.settingsAES_CTR = new SettingsAES_CTR(copyThis.settingsAES_CTR.initialCounter);
}
if (copyThis.settingsChaCha20 != null)
{
this.settingsChaCha20 = new SettingsChaCha20(copyThis.settingsChaCha20.nonce, copyThis.settingsChaCha20.counter);
}
}
/// <summary>
/// Generate new SymmetricKeyAlgorithm, you should use this instead of constructor
/// </summary>
/// <param name="symmetricEncryptionAlgorithm">Wanted Symmetric encryption algorithm</param>
/// <returns>SymmetricKeyAlgorithm</returns>
public static SymmetricKeyAlgorithm GenerateNew(SymmetricEncryptionAlgorithm symmetricEncryptionAlgorithm)
{
return(new SymmetricKeyAlgorithm(symmetricEncryptionAlgorithm, 256, (symmetricEncryptionAlgorithm == SymmetricEncryptionAlgorithm.AES_CTR) ? (object)SettingsAES_CTR.CreateWithCryptographicRandomNumbers() : (object)SettingsChaCha20.CreateWithCryptographicRandomNumbers()));
}
