Location-based and time-based photo authentication

A computer configured to access a storage device, the computer comprising:

• a processor;
• and
• a non-transitory, computer-readable storage medium storing computer-readable instructions that when executed by the processor cause the computer to perform:
• receiving a first request for authentication from a user, the first request including a current location, a current location keyword, a current timestamp, and a photo representing the current location;
• generating a pHash of the photo representing the current location;
• transmitting a second request for an encrypted true index from a server;
• receiving the encrypted true index from the server;
• interrogating a plurality of pHashes to identify a true pHash that corresponds to the encrypted true index;
• wherein the plurality of pHashes includes the true pHash and a plurality of dummy pHashes, each of the plurality of dummy pHashes being associated with a respective dummy index;
• and
• comparing the pHash of the photo representing the current location with the true pHash to determine whether to authenticate the user, wherein comparing the pHash of the photo representing the current location with the true pHash comprises determining whether a Hamming distance between the pHash of the photo representing the current location and the true pHash is below a threshold.

A computer program product comprising:

• a computer-readable storage medium having computer-readable program code embodied therewith, the computer-readable program code comprising:
• computer-readable program code configured to receive a first request for authentication from a user, the first request including a current location, a current location keyword, a current timestamp, and a photo representing the current location;
• computer-readable program code configured to determine whether the current location keyword matches a stored location keyword;
• computer-readable program code configured to determine whether the current location matches a stored location associated with the stored location keyword;
• computer-readable program code configured to determine whether the current timestamp falls within a stored time slot associated with the stored location keyword;
• computer-readable program code configured to generate a pHash of the photo representing the current location, wherein generating the pHash of the photo representing the current location comprises generating the pHash of the photo representing the current location in response to determining that the current location keyword matches the stored location keyword, determining that the current location matches the stored location associated with the stored location keyword, and determining that the current timestamp falls within the stored time slot associated with the stored location keyword.
• computer-readable program code configured to transmit a second request for an encrypted true index from a server;
• computer-readable program code configured to receive the encrypted true index from the server;
• computer-readable program code configured to interrogate a plurality of pHashes to identify a true pHash that corresponds to the encrypted true index;
• wherein the plurality of pHashes includes the true pHash and a plurality of dummy pHashes, each of the plurality of dummy pHashes being associated with a respective dummy index;
• computer-readable program code configured to compare the pHash of the photo representing the current location with the true pHash to determine whether to authenticate the user;
• wherein comparing the pHash of the photo representing the current location with the true pHash comprises computer-readable program code configured to determine whether a Hamming distance between the pHash of the photo representing the current location and the true pHash is below a threshold;
• computer-readable program code configured to determine whether the pHash of the photo representing the current location is a match to the true pHash;
• computer-readable program code configured to determine to authenticate the user, in response to determining that the pHash of the photo representing the current location is a match to the true pHash.