/// <summary>
/// Returns a platform-specific algorithm that conforms to the prescribed platform-neutral algorithm.
/// </summary>
/// <param name="algorithm">The PCL algorithm.</param>
/// <returns>
/// The platform-specific algorithm.
/// </returns>
private static Platform.SymmetricAlgorithm GetAlgorithm(SymmetricAlgorithm algorithm)
{
#if SILVERLIGHT || __IOS__
switch (algorithm)
{
case SymmetricAlgorithm.AesCbcPkcs7:
return(new Platform.AesManaged());
default:
throw new NotSupportedException();
}
#else
Platform.SymmetricAlgorithm platform = Platform.SymmetricAlgorithm.Create(
algorithm.GetName().GetString());
if (platform == null)
{
throw new NotSupportedException();
}
platform.Mode = GetMode(algorithm);
platform.Padding = GetPadding(algorithm);
return(platform);
#endif
}
/// <summary>
/// Gets the block size (in bytes) for the specified algorithm.
/// </summary>
/// <param name="pclAlgorithm">The PCL algorithm.</param>
/// <param name="algorithm">The platform-specific algorithm.</param>
/// <returns>The block size (in bytes).</returns>
internal static int GetBlockSize(SymmetricAlgorithm pclAlgorithm, Cipher algorithm)
{
Requires.NotNull(algorithm, "algorithm");
if (algorithm.BlockSize == 0 && pclAlgorithm.GetName() == SymmetricAlgorithmName.Rc4)
{
// This is a streaming cipher without a block size. Return 1 to emulate behavior of other platforms.
return(1);
}
return(algorithm.BlockSize);
}
/// <summary>Returns a crypto key management for a specified algorithm.</summary>
/// <param name="factory">The factory.</param>
/// <param name="algorithm">The algorithm.</param>
/// <returns>An instance of <see cref="ISymmetricKeyAlgorithmProvider"/>.</returns>
public static ISymmetricKeyAlgorithmProvider OpenAlgorithm(this ISymmetricKeyAlgorithmProviderFactory factory, SymmetricAlgorithm algorithm)
{
Requires.NotNull(factory, nameof(factory));
return(factory.OpenAlgorithm(algorithm.GetName(), algorithm.GetMode(), algorithm.GetPadding()));
}
/// <summary>
/// Gets the block size (in bytes) for the specified algorithm.
/// </summary>
/// <param name="pclAlgorithm">The PCL algorithm.</param>
/// <param name="algorithm">The platform-specific algorithm.</param>
/// <returns>The block size (in bytes).</returns>
internal static int GetBlockSize(SymmetricAlgorithm pclAlgorithm, Cipher algorithm)
{
Requires.NotNull(algorithm, "algorithm");
if (algorithm.BlockSize == 0 && pclAlgorithm.GetName() == SymmetricAlgorithmName.Rc4)
{
// This is a streaming cipher without a block size. Return 1 to emulate behavior of other platforms.
return 1;
}
return algorithm.BlockSize;
}
/// <summary>
/// Returns a crypto key management for a specified algorithm.
/// </summary>
/// <param name="factory">The factory.</param>
/// <param name="algorithm">The algorithm.</param>
/// <returns>An instance of <see cref="ISymmetricKeyAlgorithmProvider"/>.</returns>
public static ISymmetricKeyAlgorithmProvider OpenAlgorithm(this ISymmetricKeyAlgorithmProviderFactory factory, SymmetricAlgorithm algorithm)
{
Requires.NotNull(factory, nameof(factory));
return factory.OpenAlgorithm(algorithm.GetName(), algorithm.GetMode(), algorithm.GetPadding());
}