Making a detail texture automatic

What is the easiest way to generate cordinates (or have them generated) for a detail texture. All that really matters is that it needs to not be stretched by the method. (My hope is that I don’t have to store the texture’s cordinates.) Lastly, but detail texture, I use a texture with random bytes with values between 123 and 131, then blend them with the add signed, simply to add realilism to objects when very close.