Abstract: The present disclosure provides computing systems in which respective quorums of computing nodes securely manage respective secrets associated with cryptographic ledgers according to threshold secret sharing schemes. In particular, membership in the quorums can be changed dynamically and unpredictability to improve security of the quorums against adversarial attacks in which adversaries attempt to compromise or gain control of the computing nodes. More specifically, by changing membership in the quorum dynamically and unpredictability, the ability of the adversary to control at any given time a threshold number of the current members of the quorum and gain access to the secret is dramatically reduced.

Abstract: The present disclosure provides computing systems in which respective quorums of computing nodes securely manage respective secrets associated with cryptographic ledgers according to threshold secret sharing schemes. In particular, membership in the quorums can be changed dynamically and unpredictability to improve security of the quorums against adversarial attacks in which adversaries attempt to compromise or gain control of the computing nodes. More specifically, by changing membership in the quorum dynamically and unpredictability, the ability of the adversary to control at any given time a threshold number of the current members of the quorum and gain access to the secret is dramatically reduced.

Abstract: Processing of point of sale (“POS”) redemptions via a “tap” of a contactless device comprises a POS data collector that facilitates a connection with a contactless device. A merchant scans items for purchase using a POS scanner, which captures product identification information. The POS scanner forwards the product identification information to a POS terminal. The POS data collector intercepts the product identification information between the POS scanner and the POS terminal. A user taps the contactless device in the POS data collector's radio frequency field, and a communication channel is established between the contactless device and the POS data collector. The POS data collector identifies the user via the contactless device and identifies coupons, merchant offers, and other value-added services to redeem with the transaction. The POS data collector forwards this information to the POS terminal, the redemptions are applied to the transaction, and the communication is terminated.

Abstract: A payment processing system receives a token from a user device. Based on the first token, the payment processing system establishes a second token that remains valid longer than the first token. The payment processing system then associates the second token with a user account identifier and establishes a rescue code for use in an offline user transactions. The payment processing system then communicates the second token and the rescue code to the user device. When the user engages in an offline transaction, the payment processing system receives the rescue code and the user account identifier from the merchant computing device. Based on the user account identifier received from the merchant computing devices, the payment processing system identifies the second token and verifies that the received rescue code matches the rescue code associated with the user account identifier. Based on the verification, the payment processing system authorizes the sales transaction.

Abstract: Using a Bluetooth communication channel for point of sale processing simulates a near field communication connection. A contactless device and the point of sale reader establish an unsecure communication channel. The user taps the contactless device with a point of sale terminal reader. The contactless device creates receive signal strength indicator (“RSSI”) value spikes. The terminal reader measures the RSSI values and transmits them to the contactless device, which determines if the RSSI value reaches or exceeds a threshold configured for the contactless device. If the threshold is reached, the terminal reader and the contactless device establish a secure communication connection. The devices communicate via the secure communication connection, and the connection is terminated when a request to terminate is received.

Abstract: Using a Bluetooth communication channel for point of sale processing simulates a near field communication connection. A contactless device and the point of sale reader establish an unsecure communication channel. The user taps the contactless device with a point of sale terminal reader. The contactless device creates receive signal strength indicator (“RSSI”) value spikes. The terminal reader measures the RSSI values and transmits them to the contactless device, which determines if the RSSI value reaches or exceeds a threshold configured for the contactless device. If the threshold is reached, the terminal reader and the contactless device establish a secure communication connection. The devices communicate via the secure communication connection, and the connection is terminated when a request to terminate is received.

Abstract: Processing of point of sale (“POS”) redemptions via a “tap” of a contactless device comprises a POS data collector that facilitates a connection with a contactless device. A merchant scans items for purchase using a POS scanner, which captures product identification information. The POS scanner forwards the product identification information to a POS terminal. The POS data collector intercepts the product identification information between the POS scanner and the POS terminal. A user taps the contactless device in the POS data collector's radio frequency field, and a communication channel is established between the contactless device and the POS data collector. The POS data collector identifies the user via the contactless device and identifies coupons, merchant offers, and other value-added services to redeem with the transaction. The POS data collector forwards this information to the POS terminal, the redemptions are applied to the transaction, and the communication is terminated.

Abstract: Using a Bluetooth communication channel for point of sale processing simulates a near field communication connection. A contactless device and the point of sale reader establish an unsecure communication channel. The user taps the contactless device with a point of sale terminal reader. The contactless device creates receive signal strength indicator (“RSSI”) value spikes. The terminal reader measures the RSSI values and transmits them to the contactless device, which determines if the RSSI value reaches or exceeds a threshold configured for the contactless device. If the threshold is reached, the terminal reader and the contactless device establish a secure communication connection. The devices communicate via the secure communication connection, and the connection is terminated when a request to terminate is received.

Abstract: Processing of point of sale (“POS”) redemptions via a “tap” of a contactless device comprises a POS data collector that facilitates a connection with a contactless device. A merchant scans items for purchase using a POS scanner, which captures product identification information. The POS scanner forwards the product identification information to a POS terminal. The POS data collector intercepts the product identification information between the POS scanner and the POS terminal. A user taps the contactless device in the POS data collector's radio frequency field, and a communication channel is established between the contactless device and the POS data collector. The POS data collector identifies the user via the contactless device and identifies coupons, merchant offers, and other value-added services to redeem with the transaction. The POS data collector forwards this information to the POS terminal, the redemptions are applied to the transaction, and the communication is terminated.

Abstract: Using a Bluetooth communication channel for point of sale processing simulates a near field communication connection. A contactless device and the point of sale reader establish an unsecure communication channel. The user taps the contactless device with a point of sale terminal reader. The contactless device creates receive signal strength indicator (“RSSI”) value spikes. The terminal reader measures the RSSI values and transmits them to the contactless device, which determines if the RSSI value reaches or exceeds a threshold configured for the contactless device. If the threshold is reached, the terminal reader and the contactless device establish a secure communication connection. The devices communicate via the secure communication connection, and the connection is terminated when a request to terminate is received.