Identifying peers by their interpersonal relationships

A computer program product embodied on a non-transitory computer-readable medium, the computer program product comprising computer instructions executed by a processor to:

• process information in a data set to generate a fingerprint, the information in the data set including first data that is associated with a device identifier that only indirectly identifies a user, and second data that directly identifies an acquaintance of the user, the second data including a list, the fingerprint being generated by applying a cryptographic function over a concatenation of
• a first digest and a second digest, the first digest having been generated from the first data, and the second digest having been generated from the second data by (i) scanning the list to identify a set of entries, (ii) for each entry in the identified set of entries, including any entry that does not have a value, applying the cryptographic function to the entry to generate a hash for the entry, (iii) order the hashes generated for the entries by concatenating the hashes into a data string, and (iv) applying the cryptographic function to the data string to generate the second digest;
• and
• use the fingerprint in lieu of a username associated with the user to obtain access to a resource.