Multiple-destinational cryptosystem for broadcast networks
First Claim
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1. A method of sending a plurality of messages in the form of a single tranmission signal through a single transmitting station to a plurality of destinations through at least one receiving station comprising;
- multiplying each of said messages by an enciphering key corresponding to its intended destination;
combining the products of said multiplication step into a cryptogram comprising said single transmission signal,said cryptogram being defined by
space="preserve" listing-type="equation">x=[Σ
m.sub.i c.sub.i ] mod P,where P is the product of a plurality of prime numbers pi, ci are the enciphering keys corresponding to respective destinations and are defined by ci =di (di-1 mod pi), di is defined by P/pi, mi are numbers representing said plurality of messages, 0<
mi <
pi and 1≦
i≦
n;
transmitting said cryptogram to said at least one receiving station; and
dividing the received cryptogram by divisors corresponding to respective destinations to thereby recover the messages intended for each of said destinations.
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Abstract
A method of protecting communications through encryption is disclosed which is particularly useful for multiplexed communications. On the transmit side, each message is multiplied by an enciphering key corresponding to its destination, and the products are all added together to form a cryptogram. Each receiving station divides the entire cryptogram by its own deciphering key to obtain the message intended for that station.
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Citations
9 Claims
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1. A method of sending a plurality of messages in the form of a single tranmission signal through a single transmitting station to a plurality of destinations through at least one receiving station comprising;
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multiplying each of said messages by an enciphering key corresponding to its intended destination; combining the products of said multiplication step into a cryptogram comprising said single transmission signal, said cryptogram being defined by
space="preserve" listing-type="equation">x=[Σ
m.sub.i c.sub.i ] mod P,where P is the product of a plurality of prime numbers pi, ci are the enciphering keys corresponding to respective destinations and are defined by ci =di (di-1 mod pi), di is defined by P/pi, mi are numbers representing said plurality of messages, 0<
mi <
pi and 1≦
i≦
n;transmitting said cryptogram to said at least one receiving station; and dividing the received cryptogram by divisors corresponding to respective destinations to thereby recover the messages intended for each of said destinations. - View Dependent Claims (2, 3)
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4. In a communications system of the type in which plural messages are sent in the form of a single transmission signal from a single transmitting station to a plurality of destinations through at least one receiving station, the improvement comprising:
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a plurality of multipliers for multiplying each of said messages by an enciphering key corresponding to its intended destination; adding means for combining the outputs from said multipliers to form a cryptogram containing each of said messages and comprising said single transmission signal; and dividing means for dividing said cryptogram by deciphering keys corresponding to said plurality of destinations to thereby derive from said cryptogram the messages intended for each destination;
the improvement comprising;a cryptogram defined by
space="preserve" listing-type="equation">x=[Σ
m.sub.i c.sub.i ]mod P,where P is the product of a plurality of prime numbers pi, ci are the enciphering keys corresponding to respective destinations and are defined by ci =di (di-1 mod pi), di is defined by P/pi, mi are numbers representing said plurality of messages, 0<
mi <
Pi and 1≦
i≦
n. - View Dependent Claims (5, 6, 7, 8, 9)
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Specification