Identifying peers by their interpersonal relationships

A non-transitory computer-readable storage medium storing a computer readable program of computer instructions, wherein the computer readable program when executed by a processor causes the processor to carry out the following operations:

• scanning a contact list to identify one or more contact list entries;
• applying a cryptographic function to each identified contact entry to generate a contact entry digest for the contact entry by the following sub-steps:
• identifying one or more fields associated with a contact entry and, for a given field, applying the cryptographic function to a value in the given field or a null value if the given field does not include the value, wherein the value is derived by concatenating string representations of one of:
• first name, last name, telephone number, and e-mail address, into an intermediate data string and summing integer values of characters in the intermediate data string;
• ordering into a data string the contact entry digests;
• applying the cryptographic function to the data string to generate a fingerprint associated with the contact list;
• and
• using the fingerprint to obtain access to a protected resource.