Public Class HexStream 
   Inherits System.Security.Cryptography.CryptoStream

public class HexStream : System.Security.Cryptography.CryptoStream 

using (Stream mem = new MemoryStream())
{
    using (Stream io = new HexStream(new NonClosingStream(mem), CryptoStreamMode.Write))
        io.Write(HexEncoding.DecodeBytes(AllHex), 0, AllHex.Length / 2);

    Assert.AreEqual(AllHex.Length, mem.Position);
    mem.Position = 0;
    string test = new StreamReader(mem).ReadToEnd();
    Assert.AreEqual(AllHex, test);
}

Using mem As Stream = New MemoryStream()
    Using io As Stream = New HexStream(New NonClosingStream(mem), CryptoStreamMode.Write)
        io.Write(HexEncoding.DecodeBytes(AllHex), 0, AllHex.Length / 2)
    End Using

    Assert.AreEqual(AllHex.Length, mem.Position)
    mem.Position = 0
    Dim test As String = New StreamReader(mem).ReadToEnd()
    Assert.AreEqual(AllHex, test)
End Using