American Express Travel Related Services Company, Inc.

Hicham Lozi

Abhijeet Dutta

Rana Dasgupta

Ajit Patra

Neelanjana Dasgupta

Ramgopal Malathkar

Amit Kumar Atap

Ritwik Bhar

Lei Ma

Sharma L Putrevu

Peter John Markall

Disclosed are various embodiments for generating and verifying stateful hash-based signatures. A message hash of a message is generated using a cryptographic hash function. Then, the message hash is split into a predefined number of parts of equal size. Next, a value of a signature debt is calculated for each of the predefined number of parts of the message hash. Subsequently, a respective signature part is calculated for each of the predefined number of parts of the message hash by applying the cryptographic hash function to a respective portion of a private key for a number of times equal to the value of the signature debt. Next, the respective signature parts are concatenated to generate a signature for the message.

Stateful hash-based signatures

Disclosed herein are system, method, and computer program product embodiments for providing a diversified cryptographic Root of Trust for application instances installed on different user devices. After installing an application, a client device transmits, to a cryptography server, (1) an application identification corresponding to a key from an operating system key store on the client device and (2) a device identification specific to an instance of the application on the client device. The cryptography server uses this data to generate and transmit a unique device fingerprint to the client device. The client device then diversifies a white-box cryptography (WBC) library using the application identification, the device identification, and the device fingerprint. The diversified WBC library protects the storage of cryptographic keys obtained from the cryptography server. These keys protect sensitive data on the client device and sensitive data sent to the cryptography server and other application servers.

Diversified protection of cryptographic keys using device identification

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Palo Alto, CA, United States of America

Hicham Lozi