Abstract: A method and system for securely and efficiently processing transactions on a client computer with secure and insecure components. A secure transaction module runs on the secure components and uses certificates to authenticate client/server transactions. Users can fill in server-supplied forms with a very high degree of confidence that no malicious software has interfered, and that the server will get exactly what the user intended. The module maintains some tamper-resistant storage with labels indicating that certain registers can only be changed based on cryptographically secured commands from remote server domains. If such registers are scarce, then additional ones are simulated. Applications include managing online accounts, purchase of monetary credits that can be spent online, moving credentials on and off smart cards, using proxy signers to divide certificate authority responsibilities, creating self-destructing email documents, and digital rights management.

Abstract: A method and system for remotely maintaining data that is critical for license enforcement. The data consists of named values, is kept on a user's trusted platform, and encrypted with the use of keys that are stored in two special registers. One register is exclusively readable by a trusted program, and holds a long-term secret. Another register is exclusively writable, and changed often, so that old backups of the named values can only be read if suitable permissions are obtained. It uses a hierarchy of servers that act as vendors and have contractual obligations. Vendor certificates specify that certain named values are stored on users' trusted platforms, but owned and controlled by servers (with the cooperation of the users).

Abstract: An electronic spreadsheet system of the present invention includes a Formula Evaluator having a preferred interface and methods for compiling spreadsheet formulas into native machine language for a target processor/coprocessor. Methods are provided for improved cell lookups, whereby a system memory address for a cell record may be compiled directly into the machine language sequence for a compiled formula. Additional methods are provided for simplifying error checking. The methods adapt NaN (IEEE format) values for encoding spreadsheet ERR and NA values, so that the on-chip logic of the coprocessor may be employed for correctly propagating ERR and NA values. Preferred auditing methodology is also described, which includes further modifying the format of NaN values so that a NaN encoding an ERR or NA also embeds the address of the originating cell (i.e., the first cell which first gave rise to the ERR or NA value).

Abstract: A method for tracking errors in a system of numerical formulas. It uses confidence intervals and special encodings, and is suitable for use in an interactive computer program. Maximum efficiency and accuracy are attained by using directed rounding and compiling into native code.

Abstract: An electronic spreadsheet system of the present invention includes a Formula Evaluator having a preferred interface and methods for compiling spreadsheet formulas into native machine language for a target processor/coprocessor. Methods are provided for improved cell lookups, whereby a system memory address for a cell record may be compiled directly into the machine language sequence for a compiled formula. Additional methods are provided for simplifying error checking. The methods adapt NaN (IEEE format) values for encoding spreadsheet ERR and NA values, so that the on-chip logic of the coprocessor may be employed for correctly propagating ERR and NA values. Preferred auditing methodology is also described, which includes further modifying the format of NaN values so that a NaN encoding an ERR or NA also embeds the address of the originating cell (i.e., the first cell which first gave rise to the ERR or NA value).

Abstract: A method is given for the modular reduction of cryptographic variables, a component of many public key cryptosystems. It involves calculating a partial inverse to the modulus, partially multiplying cryptovariables, and using estimates which depend on properties of the modulus, If the estimates fail, a spill word is used. A method for choosing a modulus to get cryptographic security and maximal efficiency in modular reduction is also given.

Abstract: A method for interactive transmission of information from one computer to others across communications channels. A computer server sends asynchronous packets of data based on requests from remote terminals. The packets are interpreted in a way that allows efficient transmission of text, pictures, menus, files, and programs.

Abstract: This invention is a system and method for securely and robustly transferring a file from one computer to another without having a prearranged encryption key. Data is transferred by first generating some random numbers on each computer and undertaking some cryptographically secure handshaking in which a session key is determined. Then the file is broken up into blocks and encrypted with a chaining block cipher and transmitted. The blocks have headers which identify the them, and allow for detection and correction of transmission errors. Before retransmitting a block, an initialization vector is sent to synchronize the cipher modules. The random numbers are generated with keystroke timings combined with a pseudorandom number generator to expand the supply.

Abstract: A device for applying modular arithmetic exponentiation and reduction to an input message, and method. The device includes a partial array multiplier and an array subtracter, but requires no divider unless the modulus is changed. The intermediate results are only approximate but a correction technique makes the output signal exact.