Abstract: A system and method are provided for implementing a digital signature scheme for embedding and validating multiple nested digital signatures in digitally produced documents without modifying a file size of the digitally produced and signed documents or otherwise corrupting previously-embedded digital signatures. A number of fixed fields are included in a digitally produced document, upfront, that will be populated with multiple digital signatures. With the fixed fields in the digitally produced documents, the entire file is cryptographically “hashed” and the individual digital signatures are independently verifiable via simple cryptographic schemes. Multiple digital signatures are embedded in documents including complex file formats in a manner that does not corrupt the documents. Known cryptographic techniques such as, for example, a known hash algorithm, are applied to the digitally produced documents including the multiple sequentially input digital signatures in a process that is independently verifiable.

Abstract: A system and method are provided for implementing a digital signature scheme for embedding and validating multiple nested digital signatures in digitally produced documents without modifying a file size of the digitally produced and signed documents or otherwise corrupting previously-embedded digital signatures. A number of fixed fields are included in a digitally produced document, upfront, that will be populated with multiple digital signatures. With the fixed fields in the digitally produced documents, the entire file is cryptographically “hashed” and the individual digital signatures are independently verifiable via simple cryptographic schemes. Multiple digital signatures are embedded in documents including complex file formats in a manner that does not corrupt the documents. Known cryptographic techniques such as, for example, a known hash algorithm, are applied to the digitally produced documents including the multiple sequentially input digital signatures in a process that is independently verifiable.

Abstract: Various methods are disclosed relating to optical emanations from a light source or a first optical device that is intended to display a state of a serial data stream that crosses an interface that is associated with an information processing device. In one embodiment, the first optical device is modulated in a manner so as to not replicate the data signal being provided to and/or transmitted from the information processing device. In another embodiment, the optical emanations from the first optical device are monitored so as to be able to recover the data that is being transmitted to the information processing device in the form of a first data signal. In yet another embodiment, the cumulative optical output of a plurality of first optical devices associated with a plurality of information processing devices is monitored and evaluated in the form of a cumulative signal so as to decode each of the various individual data signals.

Abstract: Various methods are disclosed relating to optical emanations from a light source or a first optical device that is intended to display a state of a serial data stream that crosses an interface that is associated with an information processing device. In one embodiment, the first optical device is modulated in a manner so as to not replicate the data signal being provided to and/or transmitted from the information processing device. In another embodiment, the optical emanations from the first optical device are monitored so as to be able to recover the data that is being transmitted to the information processing device in the form of a first data signal. In yet another embodiment, the cumulative optical output of a plurality of first optical devices associated with a plurality of information processing devices is monitored and evaluated in the form of a cumulative signal so as to decode each of the various individual data signals.