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 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 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 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 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 (140) by using a portable device (110) that encodes a signature string to sound. The acoustic signature string may be transmitted and then decoded (150) 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: A method of generation and detection of acoustic signals carrying alpha-numeric data for reducing the effects of noise and thereby improving signal transmission without the need to boost the power of the signal. In accordance with one aspect of the invention, a special DTMF acoustic signal consisting of a combination of two frequencies will be generated for the representation of a particular alpha-numeric character that will be similar to the standard DTMF tone. The difference between the amplitudes of both frequencies varies during the time of generation of the DTMF tone in such a way that both signals will arrive at a final destination detector, i.e., an interactive voice response board, at least for a portion of the generation time, at a relatively similar amplitude, thereby substantially increasing the probabilities of being recognized as a DTMF signal.

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.