EP0064779A2
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EP
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Method and system for the mutual encyphered identification between data communicating stations and stations for use with such method and system
Assignee: Koninklijke Philips NV
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Filing: 1982-04-07
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Granted: —
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Expires: 2002-04-07
Abstract
Abstract A method for transmitting ciphered information between two stations while using session keys. According to the method a mutual identification of the stations (AK, A; A,B) is obtained while using an identification device (ID) comprised in each station. Number values (r 1 , r 2 ), originating from each station, may be exchanged by said identification in a form which is so ciphered that the number values may be recovered by the counter-part only. The session key (t m ) is formed on basis of said number values in a modification device (MODIFI). Ciphered data messages are exchanged between the station using the established session key and a message ciphering/deciphering device (MCRY, MDECRY) comprised in each station. According to the method the mutual identification and the establishment of the session key via an open channel may be obtained by transmitting one separate identification sequence in each direction.
Inventors
- 👤 Rolf Jorgen Blom
- 👤 Robert Forchheimer
- 👤 Viiveke Ann Fäk
- 👤 Bror Ingemar Ingemarsson
- 👤 Tore Ingvar Aaro
- 👤 Torgny Olof Rustan
- 👤 Pär Öman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 06:29
CPC Classifications
G; G07; G07F; G07F7/00; G07F7/08; G07F7/10; G07F7/1008; G06; G06Q; G06Q20/00; G06Q20/30; G06Q20/34; G06Q20/341; G06Q20/36; G06Q20/367; G06Q20/3674; G06Q20/38; G06Q20/388; G06Q20/40; G06Q20/409; G06Q20/4097; G06Q20/40975; G07F7/1016; H; H04; H04L; H04L9/00; H04L9/32; H04L9/3236; H04L9/3271; H04L2209/00; H04L2209/56
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
127 words
A method for the transmission of data messages between a station A (32) and a station B (34), which stations each belong to a set of equally authorized stations, each message being transmitted after encipherment by using a message ciphering key, characterized in that before transmission of data message stations A and B identify each other by means of a first identification sequence (cg1) sent in one direction and a second identification sequence (cg2) sent in the other direction, which identification sequences uniquely identify station A towards station B and vice versa, and that said message ciphering key is established independently at the respective stations on basis of the identification sequences which have been exchanged, and which may be operated upon by using a fixed modification function.
Claim 2
Independent Claim
127 words
A method for the transmission of data messages between a station A (32) and a station B (34), which stations each belong to a set of equally authorized stations, each message being transmitted after encipherment by using a message ciphering key, characterized in that before transmission of data message stations A and B identify each other by means of a first identification sequence (cg1) sent in one direction and a second identification sequence (cg2) sent in the other direction, which identification sequences uniquely identify station A towards station B and vice versa, and that said message ciphering key is established independently at the respective stations on basis of the identification sequences which have been exchanged, and which may be operated upon by using a fixed modification function.
Claim 3
Dependent Claim
56 words
A method as claimed in claim 1, characterized in that said identification sequences are exchanged as respective ciphers obtained from an identification ciphering function, and that said message ciphering key, when established, is used in a message ciphering function for the ciphering of data messages to be transmitted, which is different from the identification ciphering function.
Claim 4
Independent Claim
163 words
A method as claimed in claims 1 or 2, characterized in that each identification sequence has the form of a ciphered number value, being preferably a pseudo-random number; that station A transmits a ciphered first number value which may be deciphered by station B only; that station B deciphers and transmits back to station A said first number value in a form which may be deciphered and evaluated by station A only; that station B transmits to station A a ciphered second number value which may deciphered by station A only; and that station A deciphers and transmits back to station B said second number value in a form which may be deciphered and evaluated by station B only, while said first and second number values which are received and deciphered at the respective stations may be converted by means of a transformation function, which is known by the stations, before the same are ciphered again and transmitted back to the respective counterparts.
Claim 5
Dependent Claim
93 words
A method as claimed in claim 2 or 3, characterized in that station A transmits to station B a first cipher comprising said first number value; that the station B transmits back to station A a second cipher comprising said second number value and the deciphered first number value; and that station A transmits back to station B a third cipher comprising the deciphered second number value, while said third cipher may be accompanied by a data message which is ciphered by means of said message ciphering function and said message ciphering key.
Claim 6
Dependent Claim
148 words
A method as claimed in claim 1, 2, 3 or 4, characterized in that said first and second number values are ciphered and deciphered while using as said identification ciphering function, a ciphering function and its inverse and different keys for ciphering and deciphering, to each station being allotted a public ciphering key and a deciphering key associated therewith and kept secret in the station, each station having from the starting point a knowledge about its own secret deciphering key, the public ciphering key of the counterpart and said ciphering function and its inverse.-6. A method as claimed in claim 3, 4 or 5, characterized in that the transformation function for converting said number values is a one-way function, meaning that a number value may not be recovered practically even with a knowledge about the function and the number value in the form as modified by said function.
Claim 7
Independent Claim
58 words
A method as claimed in anyone of the claims 3 - 6, characterized in that each station is arranged so as to break the connection when a correspondence fails to appear between the, outcome of the transformation function from its own number value and the outcome of the transformation function received in said second and third ciphers, respectively.
Claim 8
Independent Claim
81 words
A method as claimed in anyone of the preceding claims in which a station may appear in the shape of a personal data carrier built as an active card, and which at least one station comprising means for supplying and evaluating a personal code, characterized in that the transmission of said identification sequences or number values is initiated by an evaluation of the supplied personal code which is carried out and accepted internally in said station or on said data carrier.
Claim 9
Dependent Claim
178 words
A transmission system for carrying out the method as claimed in anyone of the previous claims, characterized in that each station of the system is provided with an identification device for a mutual identification of a cooperating station while using an identification ciphering function and its inverse and a pair of keys which is allotted to the station and comprising a public ciphering key and a deciphering key which is kept secret in the station, said identification device comprising a number generator for generating a number value as an identification sequence, a ciphering device for ciphering said number value while using said ciphering function and the public ciphering key of the counterpart, a deciphering device for detecting a number value received from the counterpart while using the inverse of said ciphering function and the secret deciphering key of the station; a modification device for generating a message ciphering key based on the number values which have been exchanged; and a message ciphering/deciphering device for ciphering and deciphering data messages while using the message ciphering key which is generated.
Claim 10
Dependent Claim
67 words
1 0. A system as claimed in claim 9, characterized in that said identification device comprises a number converter for converting said number values while using a transformation function and a comparator for comparing the number value of the station in the form which is converted internally with the form converted by the counter- part and to generate a blocking signal when an agreement fails to appear.
Claim 11
Dependent Claim
30 words
A system as claimed in claim 9 or 10, characterized in that each station furthermore comprises a blocking device for blocking a used transmission channel dependent on said blocking signal.
Claim 12
Dependent Claim
83 words
A system as claimed in claim 9, 10 or 11, in which a station may appear in the form of a personal data carrier built as an active card, characterized in that at least one station comprises means for supplying and evaluation a personal code and means for activating temporarily said station or said data carrier and to-initiate the exchange of said number values dependent on an evaluation which is carried out and accepted internally in the station or on the data carrier.
Claim 13
Dependent Claim
39 words
A station for use in a system according to any of the claims 9 - 12, characterized in that it comprises identification means (36), modifying means (38) cyphering- cum decyphering means (44/46), and message generating cum receiving means (40/42).
Claim 14
Dependent Claim
32 words
A station as claimed in claim 13, characterized in that it is provided with key means (32) for entering a personal identification code for comparison (80) with an internally generated code (78)
References Cited (Backward Citations)
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