1. A method, comprising: receiving, by a processor, a database containing records; determining, by a processor, a number of artificial records to add to the database to achieve a false negative mark detection rate less than a specified threshold; and marking, by the processor, said database by adding the determined number of artificial records to the database, each artificial record containing at least one value that, when used, is detectable by a third party; wherein said false negative rate comprises a probability of failing to detect the mark in a discovered subset of the database.