International Business Machines Corporation

Subramaniyam Chandrasekaran

Arun C Ramachandran

Lakshmanan Velusamy

Shunmugam Murugan

Vinodh Kumar Venkatesan

A confidential information exchange between a sender and a receiver may be conducted without the use of encryption keys. The information is coded with a Challenge-Response Table that is shared between the sender and the receiver. Rather than sending a challenge and then waiting for a response, the challenge and response are both sent by the sender of the information. The information sent comprises an index with a challenge and a response from the Challenge-Response Table. Upon receiving the coded information, the receiver uses the Challenge-Response Table to decode the information by using the index to locate the challenge and its valid response. Upon determining that the challenge and the response are correct, a first decoded answer is determined. Upon determining that either the challenge or the response, or both, are incorrect, a second decoded answer is determined.

Keyless challenge and response system

The invention includes a method for encrypting and transmitting a message M from a first location to a second location. Random numbers P and Q are initially selected, each of them being either a prime or a non-prime number. P and Q are both furnished to a sender and a recipient at the first and second locations, respectively. A client at the first location generates an encrypted message E, which is the remainder left when a modulus operator divides a first quantity, equal to M multiplied by P to the i power, where i is a selected number, by a second quantity equal to (PQ&#x2212;1). A tuple comprising E and i is transmitted from the first location to the second location, and a second data processing system at the second location to determines the message M from E, i and Q.

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Bengaluru, India

Subramaniyam Chandrasekaran