# US 11,115,436 B2 · Footprint data to prevent man-in-the-middle attacks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,115,436 B2 - Document ID: US11115436B2 - Status: Granted - Kind: B2 - Application number: 16/434,081 - Filed: 2019-06-06 - Published: 2020-12-10 - Granted: 2021-09-07 - Earliest claimed: 2019-06-06 - Assignees: Visa International Service Association - Applicants: Visa International Service Association - Inventors: Fahimeh Rezaei; Marc Kekicheff; Yuexi Chen - Web page: https://patentgrep.com/patent/US11115436B2 ## CPC - H04L 63/1466: {Active attacks involving interception, injection, modification, spoofing of data unit addresses, e.g. hijacking, packet injection or TCP sequence number attacks} - H04L 63/0876: {based on the identity of the terminal or configuration, e.g. MAC address, hardware or software configuration or device fingerprint} - H04L 63/10: {for controlling access to devices or network resources} - H04L 63/108: {when the policy decisions are valid for a limited amount of time} - H04W 12/06: Authentication - H04W 12/61: Time-dependent - H04L 2463/121: Timestamp - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Systems and methods are disclosed for preventing relay or replay attacks using time-stamped, localized footprint data. An access device may receive, from one or more beacon transmitters, a plurality of broadcast messages, each broadcast message, of the plurality of broadcast messages, comprising a timestamp and a unique identifier for a beacon transmitter, of the one or more beacon transmitters. The access device may store the timestamps and the unique identifiers. The access device may receive, from a user device, an access request comprising timestamps and unique identifiers corresponding to a subset of the broadcast messages received by the access device. The access device may verify that the stored timestamps and unique identifiers match the timestamps and unique identifiers received from the user device. Based on the verifying, the access device may authenticate the access request. ## Claims ### Claim 1 A method comprising: receiving, at an access device from one or more beacon transmitters, a plurality of broadcast messages, each broadcast message, of the plurality of broadcast messages, comprising a timestamp and a unique identifier of a beacon transmitter, of the one or more beacon transmitters; storing, by the access device, the timestamps and the unique identifiers; receiving, at the access device from a user device, an access request comprising timestamps and unique identifiers corresponding to a subset of the broadcast messages received by the access device; verifying, by the access device, that the stored timestamps and unique identifiers match the timestamps and unique identifiers received from the user device; and based on the verifying, authenticating, by the access device, the access request. ### Claim 2 (depends on 1) The method of claim 1, wherein the plurality of broadcast messages are received from a plurality of respective beacon transmitters, each beacon transmitter comprising a different unique identifier. ### Claim 3 (depends on 1) The method of claim 1, wherein the plurality of broadcast messages are received from one beacon transmitter at one or more randomly distributed time intervals. ### Claim 4 (depends on 1) The method of claim 1, wherein the timestamps and the unique identifiers received from the user device are in a form of a cryptogram, and wherein the verifying comprises decrypting the cryptogram to recover the timestamps and the unique identifier, and comparing the recovered timestamps and the unique identifier to the stored timestamps and unique identifiers. ### Claim 5 (depends on 1) The method of claim 1, wherein the unique identifier comprises a random number. ### Claim 6 (depends on 1) The method of claim 1, further comprising, based on authenticating the access request: transmitting an authorization request message to a processing system, wherein the processing system initiates authorization operations for the access request. ### Claim 7 (depends on 1) The method of claim 1, further comprising identifying, by the access device, the stored timestamps and unique identifiers corresponding to the subset of the broadcast messages received by the user device. ### Claim 8 An access device comprising: a processor; and a non-transitory computer-readable medium comprising code, executable by the processor, for implementing a method comprising: receiving, at the access device from one or more beacon transmitters, a plurality of broadcast messages, each broadcast message, of the plurality of broadcast messages, comprising a timestamp and a unique identifier of a beacon transmitter, of the one or more beacon transmitters; storing, by the access device, the timestamps and the unique identifiers; receiving, at the access device from a user device, an access request comprising timestamps and unique identifiers corresponding to a subset of the broadcast messages received by the access device; verifying, by the access device, that the stored timestamps and unique identifiers match the timestamps and unique identifiers received from the user device; and based on the verifying, authenticating, by the access device, the access request. ### Claim 9 (depends on 8) The access device of claim 8, wherein the plurality of broadcast messages are received from a plurality of respective beacon transmitters, each beacon transmitter comprising a different unique identifier. ### Claim 10 (depends on 8) The access device of claim 8, wherein the plurality of broadcast messages are received from one beacon transmitter at one or more randomly distributed time intervals. ### Claim 11 (depends on 8) The access device of claim 8, wherein the timestamps and the unique identifiers received from the user device are in a form of a cryptogram, and wherein the verifying comprises decrypting the cryptogram to recover the timestamps and the unique identifier, and comparing the recovered timestamps and the unique identifier to the stored timestamps and unique identifiers. ### Claim 12 (depends on 8) The access device of claim 8, wherein the unique identifier comprises a random number. ### Claim 13 (depends on 8) The access device of claim 8, the method further comprising, based on authenticating the access request: transmitting an authorization request message to a processing system, wherein the processing system initiates authorization operations for the access request. ### Claim 14 (depends on 8) The access device of claim 8, further comprising identifying, by the access device, the stored timestamps and unique identifiers corresponding to the subset of the broadcast messages received by the user device. ### Claim 15 A method comprising: receiving, at a user device from a one or more beacon transmitters, a plurality of broadcast messages, each broadcast message, of the plurality of broadcast messages, comprising a timestamp and a unique identifier; and preparing and transmitting to an access device, by the user device, an access request comprising a set of timestamps and unique identifiers corresponding to the plurality of broadcast messages received by the user device; wherein the access device: verifies that a set of stored timestamps and unique identifiers match the set of timestamps and unique identifiers received from the user device, and based on the verifying, authenticates the access request. ### Claim 16 (depends on 15) The method of claim 15, further comprising, based on the plurality of broadcast messages, identifying, by the user device, the access device, of a plurality of potential access devices, to which to transmit the access request. ### Claim 17 (depends on 15) The method of claim 15, wherein the plurality of broadcast messages are received from a plurality of respective beacon transmitters, each beacon transmitter comprising a different unique identifier. ### Claim 18 (depends on 15) The method of claim 15, wherein the plurality of broadcast messages are received from one beacon transmitter at a one or more randomly distributed time intervals. ### Claim 19 (depends on 15) The method of claim 15, wherein the timestamps and the unique identifiers received from the user device are in a form of a cryptogram, and wherein the verifying comprises decrypting the cryptogram to recover the timestamps and the unique identifier, and comparing the recovered timestamps and the unique identifier to the stored timestamps and unique identifiers. ### Claim 20 (depends on 15) The method of claim 15, wherein the unique identifier comprises a random number.