//http://bitcoinj.googlecode.com/git-history/keychain/core/src/main/java/com/google/bitcoin/core/Utils.java
public static byte[] CreateEncodedMessageD2(string message)
{
byte[] messageBytes = Encoding.UTF8.GetBytes(message);
MemoryStream ms = new MemoryStream();
ms.WriteByte((byte)BITCOIN_SIGNED_MESSAGE_HEADER_BYTES.Length);
Write(ms, BITCOIN_SIGNED_MESSAGE_HEADER_BYTES);
VarInt size = new VarInt((ulong)messageBytes.Length);
Write(ms, size.ToBytes());
Write(ms, messageBytes);
byte[] data = ms.ToArray();
using (var sha = new SHA256Managed())
{
var h = sha.ComputeHash(data, 0, data.Length);
return sha.ComputeHash(h, 0, h.Length);
}
}