Decryption of messages employing unique control words and randomly chosen decryption keys
First Claim
1. For use in a communication network of the type in which a transmitting station sends an encrypted message to a plurality of receiving stations in a manner that enables only a selected receiving station in said plurality to decrypt the messages, a method of operation each receiving station, wherein:
- each of said receiving stations stores one and the same set of several decryption keys;
each of said receiving stations stores a control word which is any series of bits that is unique to that station; and
each of said receiving stations identifies an encrypted message as being sent to it by--(a) automatically choosing a decryption key at random from said set, (b) performing a decrypt operation on the same portion of the encrypted message from said transmitting station using the selected key, (c) comparing the result of said decrypt operation to its stored control word, and (d) repeating steps (a) thru (c) until either a match occurs or all keys in said set have been selected.
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Accused Products
Abstract
In a communication network, a transmitting station sends encrypted messages to several receiving stations. Each receiving station stores one and the same set of decryption keys; and it stores a control word which is a series of bits that is unique to that station. Also, each receiving station identifies an encrypted message as being sent to it by -- (a) automatically selecting a decryption key at random from the set, (b) performing a decrypt operation on the same portion of the encrypted message from the transmitting station using the selected key, (c) comparing the result of the decrypt operation to its stored control word, and (d) repeating steps (a) thru (c) until either a match occurs or all keys in the set have been selected.
69 Citations
14 Claims
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1. For use in a communication network of the type in which a transmitting station sends an encrypted message to a plurality of receiving stations in a manner that enables only a selected receiving station in said plurality to decrypt the messages, a method of operation each receiving station, wherein:
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each of said receiving stations stores one and the same set of several decryption keys; each of said receiving stations stores a control word which is any series of bits that is unique to that station; and each of said receiving stations identifies an encrypted message as being sent to it by--(a) automatically choosing a decryption key at random from said set, (b) performing a decrypt operation on the same portion of the encrypted message from said transmitting station using the selected key, (c) comparing the result of said decrypt operation to its stored control word, and (d) repeating steps (a) thru (c) until either a match occurs or all keys in said set have been selected. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. For use in a communication network of the type in which a transmitting station sends an encrypted message to a plurality of receiving stations in a manner that enables only a selected receiving station in said plurality to decrypt the messages, a module for inclusion within each receiving station which comprises:
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one and the same set of several decryption keys; a control word which is any series of bits that is unique to each receiving station; and a control circuit including (a) a means for automatically choosing a decryption key at random from said set, (b) a means for performing a decrypt operation on the same portion of the encrypted message from said transmitting station using the selected key, (c) a means for comparing the result of said decrypt operation to the stored control word, and (d) a means for reactivating means (a) thru (c) until either a match occurs or all keys in said set have been selected. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification