Abstract: Payment systems are provided that utilize a portable device, and in particular, payment systems that utilize a first portable device that belongs to a seller and a second portable device that belongs to a buyer, but do not utilize a point of sale (POS) device.

Abstract: An authentication system is provided that includes a portable device and a decryption node. An individual uses the portable device, such as a portable device like a cell phone to compute a challenge and a response. The challenge and response is sent to a decryption node. In response, the decryption node computes a presumed response and compares the presumed response to the response of the portable device, in order to authenticate the individual associated with the portable device.

Abstract: Methods for identifying a remote user of a portable device by using the portable device to encode sound corresponding to the identification of the remote user. The sound is received by a microphone external to the portable device and converted to an electrical signal. The electrical signal is transmitted to a processing device, that may be remote to the microphone, where the electrical signal is processed and the identification of the remote user is completed.

Abstract: Methods and device for digitally signing documents by using a portable device that encodes a signature string to sound. The acoustic signature string may be transmitted and then decoded back into digital data. The signature string may be further processed to verify the signature of the document and to produce a certificate of identity and integrity for the document. The certificate of identity and integrity may be used to further identify and validate the document and its signer.

Abstract: Methods for identifying a remote user of a portable device by using the portable device to encode sound corresponding to the identification of the remote user. The sound is received by a microphone external to the portable device and convened to an electrical signal. The electrical signal is transmitted to a processing device, that may be remote to the microphone, where the electrical signal is processed and the identification of the remote user is completed.

Abstract: Methods for the secure identification of the owner of a portable device by a service provider, wherein the portable device may be in communication with the service provider over a voice line such as a telephone line or the like, and the portable device does not require a personal computer. Furthermore, the methods provide for one-way, non-repudiable, non-trackable identification of the owner of a portable device, and for the arbitration of a disputed transaction between the owner of a portable device and a service provider.

Abstract: Methods and device for digitally signing documents by using a portable device that encodes a signature string to sound. The acoustic signature string may be transmitted and then decoded back into digital data. The signature string may be further processed to verify the signature of the document and to produce a certificate of identity and integrity for the document. The certificate of identity and integrity may be used to further identify and validate the document and its signer.

Abstract: An encryption system for transmitting confidential data from a transmitting device comprising: a processor fore effecting a dynamic algorithm which is a function of time, e.g., Greenwich Mean Time; means for entering confidential data into the transmitting device; means for encrypting at least a portion of said confidential data in accordance with said algorithm; means for transmitting the resulting encrypted data; means for decrypting the received data, including circuitry which embodies the inverse of said dynamic function; means for extracting said confidential data from the encrypted data in accordance with said inverse dynamic algorithm. The system is intended to be used for electronic funds transfers: e.g., for credit card transactions.

Abstract: The present invention provides methods and apparatus for the transmission of encrypted data along conventional telephone lines using various data transmission techniques, including known dual tone multi-frequency(DMTF) techniques. In accordance with a preferred embodiment of the invention, an exemplary apparatus for transmitting confidential information(data) comprises a portable hand-held module having the confidential data(e.g., credit card account numbers) and a predetermined encryption algorithm embedded therein. The apparatus which receives the encrypted transmission is equipped with an interface computer having decryption circuitry in which the inverse of the forgoing encryption algorithm is embedded.