Permuting records in a database for leak detection and tracing

A non-transitory computer-readable storage medium (CRSM) containing software that, when executed by a processor, causes the processor to:

• receive a copy of a database containing records, each record having a plurality of attributes;
• determine whether a first attribute in each record results in a predetermined value in modulo P when hashed with a key;
• and
• determine whether a second attribute in each record results in a predetermined value in modulo P when hashed with a key;
• for a first record whose first attribute results in the predetermined value in modulo P when hashed with a key and a second record whose second attribute also results in the predetermined value in modulo P when hashed with a key, swap said second attributes between the first and second records;
• and
• wherein a plurality of records have a second attribute that results in the predetermined value in modulo P when hashed with a key, and the software further causes the processor to apply a distance function to help determine which of such records to select as the second record for swapping the second attributes.

A method, comprising:

• receiving, by a processor, a copy of a database containing records, each record having a plurality of attributes;
• selecting two attributes to be a first attribute and a second attribute;
• determining, by the processor, the number of records that have the first attribute and the second attribute that each results in a predetermined value in modulo P when hashed with a key;
• and
• determining, by the processor, whether the number is greater than a threshold;
• determining, by the processor, the database copy to have been marked using the key and the first and second attributes if the number is greater than the threshold, a database copy having been marked through application of a distance function to determine which of the records to select for swapping;
• and
• determining, by the processor, the database copy not to have been marked using the key if the number is less than the threshold.