Json.net ContractResolver [duplicate]

How to find out if called from Serializiaton or deserialization ?

I need something like this:

protected override IValueProvider CreateMemberValueProvider(MemberInfo member)
{
    IValueProvider valueProvider = base.CreateMemberValueProvider(member);

    if (member.CustomAttributes.First().AttributeType == typeof(EncryptedAttribute))
    {
        object value = valueProvider.GetValue(_object);
        if(IsInSerialization())
        {
            valueProvider.SetValue(_object, Encrypt(value));
        }
        else
        {
            valueProvider.SetValue(_object, Decrypt(value));
        }
    }
    return valueProvider;
}