/// <summary>
/// Gets an <see cref="ICryptoTransform"/> instance to use for a given cryptographic key.
/// </summary>
/// <param name="key">The cryptographic key to use in the transform.</param>
/// <param name="iv">The initialization vector to use, when applicable.</param>
/// <param name="encrypting"><c>true</c> if encrypting; <c>false</c> if decrypting.</param>
/// <returns>An instance of <see cref="ICryptoTransform"/>.</returns>
private static ICryptoTransform GetTransformForBlockMode(CryptographicKey key, byte[] iv, bool encrypting)
{
Requires.NotNull(key, "key");
var bufferOperation = encrypting
? new Func <byte[], byte[]>(input => Platform.Core.CryptographicEngine.Encrypt(key.Key, input.ToBuffer(), iv.ToBuffer()).ToArray())
: new Func <byte[], byte[]>(input => Platform.Core.CryptographicEngine.Decrypt(key.Key, input.ToBuffer(), iv.ToBuffer()).ToArray());
return(new BufferingCryptoTransform(bufferOperation));
}
/// <summary>
/// Checks whether the given length is a valid one for an input buffer to the symmetric algorithm.
/// </summary>
/// <param name="key">The key.</param>
/// <param name="lengthInBytes">The length of the input buffer in bytes.</param>
/// <returns>
/// <c>true</c> if the size is allowed; <c>false</c> otherwise.
/// </returns>
private bool IsValidInputSize(CryptographicKey key, int lengthInBytes)
{
Requires.NotNull(key, "key");
return(lengthInBytes > 0 && lengthInBytes % key.SymmetricAlgorithmProvider.BlockLength == 0);
}
/// <summary>
/// Checks whether the given length is a valid one for an input buffer to the symmetric algorithm.
/// </summary>
/// <param name="key">The key.</param>
/// <param name="lengthInBytes">The length of the input buffer in bytes.</param>
/// <returns>
/// <c>true</c> if the size is allowed; <c>false</c> otherwise.
/// </returns>
private bool IsValidInputSize(CryptographicKey key, int lengthInBytes)
{
Requires.NotNull(key, "key");
return lengthInBytes > 0 && lengthInBytes % key.SymmetricAlgorithmProvider.BlockLength == 0;
}
/// <summary>
/// Gets an <see cref="ICryptoTransform"/> instance to use for a given cryptographic key.
/// </summary>
/// <param name="key">The cryptographic key to use in the transform.</param>
/// <param name="iv">The initialization vector to use, when applicable.</param>
/// <param name="encrypting"><c>true</c> if encrypting; <c>false</c> if decrypting.</param>
/// <returns>An instance of <see cref="ICryptoTransform"/>.</returns>
private static ICryptoTransform GetTransformForBlockMode(CryptographicKey key, byte[] iv, bool encrypting)
{
Requires.NotNull(key, "key");
var bufferOperation = encrypting
? new Func<byte[], byte[]>(input => Platform.Core.CryptographicEngine.Encrypt(key.Key, input.ToBuffer(), iv.ToBuffer()).ToArray())
: new Func<byte[], byte[]>(input => Platform.Core.CryptographicEngine.Decrypt(key.Key, input.ToBuffer(), iv.ToBuffer()).ToArray());
return new BufferingCryptoTransform(bufferOperation);
}
