Public Function GenerateMySQLHash(ByVal strKey As String) As String

    Dim keyArray As Byte() = System.Text.UTF8Encoding.UTF8.GetBytes(strKey)
    Dim enc = New Security.Cryptography.SHA1Managed()
    Dim encodedKey = enc.ComputeHash(enc.ComputeHash(keyArray))
    Dim myBuilder As New System.Text.StringBuilder(encodedKey.ToString.Length)

    For Each b As Byte In encodedKey
        myBuilder.Append(Strings.Right("0" & b.ToString("X"), 2))
    Next

    Return "*" & myBuilder.ToString()
End Function

public string GenerateMySQLHash(string key)
{
    byte[] keyArray = Encoding.UTF8.GetBytes(key);
    SHA1Managed enc = new SHA1Managed();
    byte[] encodedKey = enc.ComputeHash(enc.ComputeHash(keyArray));
    StringBuilder myBuilder = new StringBuilder(encodedKey.Length);

    foreach (byte b in encodedKey)
        myBuilder.Append(b.ToString("X"));

    return "*" + myBuilder.ToString();
}