Abstract: The present system and method uses multiple digital devices with possibly different users operating in concert, for performing authentication and other cryptographic operations. The multiple digital devices include, for example, a mobile device such as a cellular phone, as a central building block.

Abstract: A system for generating a computing system specific value comprising, a computing system not comprising any specialized hardware to generate a device specific value, a software product tangibly embodied in a machine-readable medium, comprising instructions operable to cause computing system to perform operations comprising: generating a digital value which is substantially dependent on manufacturing variation among like devices of computing system.

Abstract: In various embodiments, transactions initiated by or on behalf of users between client systems and transaction systems are sent to authorization systems for approval. An authorization system contacts one or more registered devices for approval from a user of the registered devices for the transactions initiated by or on behalf of the users that are being handled by the transaction systems. A registered device sends an approval or denial based on user input. The authorization server then sends the approval or denial to a transaction system to complete a transaction.

Abstract: A system for generating a computing system specific value comprising, a computing system not comprising any specialized hardware to generate a device specific value, a software product tangibly embodied in a machine-readable medium, comprising instructions operable to cause computing system to perform operations comprising: generating a digital value which is substantially dependent on manufacturing variation among like devices of computing system.

Abstract: The present system and method uses multiple digital devices with possibly different users operating in concert, for performing authentication and other cryptographic operations. The multiple digital devices include, for example, a mobile device such as a cellular phone, as a central building block.