Cryptosystem for cellular telephony
First Claim
1. In a communications system, a method of transforming a set of message signals representing a message, the method which includes the steps ofencrypting said set of message signals with an encryption process and a set of key signals to form a set of first intermediate signals,altering said set of first intermediate signals in accordance with an involutory transformation to form a set of second intermediate signals, and decrypting said set of second intermediate signals with a decryption process which is the inverse of said encryption process to form a set of output signals,Characterized in that:
- said step of altering comprises the step of modifying a first subset of said set of first intermediate signals with an unkeyed transformation based on a second subset of said set of first intermediate signals.
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Abstract
A relatively secure, self-inverting, symmetric key cryptosystem designed for efficient implementation on an 8-bit microcomputer. The cryptosystem is especially well suited use in cellular telephony. The method of encryption is comprised of three stages: 1) an autokeyed encryption, 2) the use of a one-time pad encryption where the key is derived from a portion of the message as encrypted by the first stage, and 3) a second autokeyed decryption that is the inverse of the first.
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Citations
24 Claims
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1. In a communications system, a method of transforming a set of message signals representing a message, the method which includes the steps of
encrypting said set of message signals with an encryption process and a set of key signals to form a set of first intermediate signals, altering said set of first intermediate signals in accordance with an involutory transformation to form a set of second intermediate signals, and decrypting said set of second intermediate signals with a decryption process which is the inverse of said encryption process to form a set of output signals, Characterized in that: said step of altering comprises the step of modifying a first subset of said set of first intermediate signals with an unkeyed transformation based on a second subset of said set of first intermediate signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A cryptographic system for transforming a set of message signals which set represents a message comprising:
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means for encrypting said set of message signals with an encryption process and a set of key signals to form a set of first intermediate signals; means for altering said set of first intermediate signals in accordance with an involutory transformation to form a set of second intermediate signals; and means for decrypting said set of second intermediate signals with a decryption process which is the inverse of said encryption process to form a set of output signals, Characterized in that; said means for altering comprises means for modifying a first subset of said set of first intermediate signals with an unkeyed transformation in accordance with a second subset of said set of first intermediate signals. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification