/// <summary>
/// Creates a new instance of a <see cref="CascadingSymmetricKey" /> using the specified buffer.
/// </summary>
/// <param name="buffer">
/// A binary representation of a <see cref="CascadingSymmetricKey" />.
/// </param>
/// <returns>
/// A new instance of a <see cref="CascadingSymmetricKey" />.
/// </returns>
/// <exception cref="ArgumentException">
/// <paramref name="buffer" /> is invalid.
/// </exception>
/// <exception cref="ArgumentNullException">
/// <paramref name="buffer" /> is <see langword="null" />.
/// </exception>
public static CascadingSymmetricKey FromBuffer(SecureBuffer buffer)
{
buffer.RejectIf().IsNull(nameof(buffer)).OrIf(argument => argument.Length != SerializedLength, nameof(buffer), "The specified buffer is invalid.");
try
{
var keys = (SecureSymmetricKey[])null;
buffer.Access(pinnedBuffer =>
{
// Interrogate the final 16 bits to determine the depth.
var keyLength = SecureSymmetricKey.SerializedLength;
var depth = BitConverter.ToUInt16(pinnedBuffer, (SerializedLength - sizeof(UInt16)));
keys = new SecureSymmetricKey[depth];
for (var i = 0; i < depth; i++)
{
using (var secureBuffer = new SecureBuffer(keyLength))
{
secureBuffer.Access(keyBuffer =>
{
// Copy out the key buffers.
Array.Copy(pinnedBuffer, (keyLength * i), keyBuffer, 0, keyLength);
});
keys[i] = SecureSymmetricKey.FromBuffer(secureBuffer);
}
}
});
return(new CascadingSymmetricKey(keys));
}
catch
{
throw new ArgumentException("The specified buffer is invalid.", nameof(buffer));
}
}
/// <summary>
/// Creates a new instance of a <see cref="SecureSymmetricKey" /> using the specified buffer.
/// </summary>
/// <param name="buffer">
/// A binary representation of a <see cref="SecureSymmetricKey" />.
/// </param>
/// <returns>
/// A new instance of a <see cref="SecureSymmetricKey" />.
/// </returns>
/// <exception cref="ArgumentException">
/// <paramref name="buffer" /> is invalid.
/// </exception>
/// <exception cref="ArgumentNullException">
/// <paramref name="buffer" /> is <see langword="null" />.
/// </exception>
public static SecureSymmetricKey FromBuffer(SecureBuffer buffer)
{
buffer.RejectIf().IsNull(nameof(buffer)).OrIf(argument => argument.Length != SerializedLength, nameof(buffer), "The specified buffer is invalid.");
try
{
var result = (SecureSymmetricKey)null;
buffer.Access(pinnedCiphertext =>
{
using (var plaintextBuffer = new PinnedBuffer(SerializedPlaintextLength, true))
{
using (var cipher = BufferEncryptionAlgorithm.ToCipher(RandomnessProvider))
{
using (var plaintext = cipher.Decrypt(pinnedCiphertext, BufferEncryptionKey))
{
Array.Copy(plaintext, 0, plaintextBuffer, 0, SerializedPlaintextLength);
}
}
using (var keySource = new PinnedBuffer(KeySourceLengthInBytes, true))
{
Array.Copy(plaintextBuffer, KeySourceBufferIndex, keySource, 0, KeySourceLengthInBytes);
var algorithm = (SymmetricAlgorithmSpecification)plaintextBuffer[AlgorithmBufferIndex];
var derivationMode = (SecureSymmetricKeyDerivationMode)plaintextBuffer[DerivationModeBufferIndex];
result = new SecureSymmetricKey(algorithm, derivationMode, keySource);
}
}
});
return(result);
}
catch
{
throw new ArgumentException("The specified buffer is invalid.", nameof(buffer));
}
}