US4951247A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Data exchange system comprising a plurality of user terminals each containing a chip card reading device
Assignee: Siemens AG
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Filing: 1988-03-04
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Granted: 1990-08-21
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Expires: 2008-03-04
Abstract
Abstract A secret cipher (Ki) that is the same for all user terminals is formed of two sub-components (KTi, KT'i) whereof the one sub-component (KTi) is deposited in an erasable, programmable read-only memory (EEPROM). For the second sub-component (KT'i), an encoded data block (E(KT'i)) is transmitted from the outside to a decoder means (DEC) provided in the security module, the decoded output signal thereof being deposited as second sub-component (KT'i) in a first sub-area of a write-read memory (RAM) present in the security module of the user terminal. An overall cipher (Ki) is calculated from the two sub-components (KTi, KT'i) and the result is deposited in a second sub-area of the write-read memory (RAM).
Inventors
- 👤 Dietrich Kruse
- 👤 Albrecht Beutelspacher
- 👤 Annette-Gabriele Kersten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:22
CPC Classifications
G; G07; G07F; G07F7/00; G07F7/08; G07F7/10; G07F7/1008; G06; G06Q; G06Q20/00; G06Q20/22; G06Q20/229; G06Q20/30; G06Q20/34; G06Q20/341; G06Q20/38; G06Q20/40; G06Q20/409; G06Q20/4097; G06Q20/40975; H; H04; H04L; H04L9/00; H04L9/08; H04L9/0861; H04L9/0877
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
158 words
A data exchange system comprising a plurality of terminals each containing a chip card reading device, a security module for storing a secret key, which key is identical for all terminals, said secret key (Ki) being formed of two sub-components (KTi, KT'i); said security module having an erasable programmable read-only memory (EEPROM) for storing one sub-component (KTi); a decoder means (DEC) provided in the security module; said decoder means having an input for receiving an enciphered data block (E(Kt'i)) for the second sub-component (KT'i) from outside said security module; said security module having a write-read memory (RAM), for receiving and storing the decoded output signals from said decoder means as a second subcomponent (KT'i) in a first sub-area of said write-read memory (RAM); and said security module having means for operating on said two sub-components (KTi, KT'i) to form a result which is deposited in a second sub-area of the read-write memory (RAM) as an overall key (Ki).
Claim 2
Dependent Claim
158 words
A data exchange system comprising a plurality of terminals each containing a chip card reading device, a security module for storing a secret key, which key is identical for all terminals, said secret key (Ki) being formed of two sub-components (KTi, KT'i); said security module having an erasable programmable read-only memory (EEPROM) for storing one sub-component (KTi); a decoder means (DEC) provided in the security module; said decoder means having an input for receiving an enciphered data block (E(Kt'i)) for the second sub-component (KT'i) from outside said security module; said security module having a write-read memory (RAM), for receiving and storing the decoded output signals from said decoder means as a second subcomponent (KT'i) in a first sub-area of said write-read memory (RAM); and said security module having means for operating on said two sub-components (KTi, KT'i) to form a result which is deposited in a second sub-area of the read-write memory (RAM) as an overall key (Ki).
Claim 3
Dependent Claim
98 words
The data exchange system according to claim 1, including means for storing a randomly chosen auxiliary key (KO) in said security module, an initialization card (IK) for storing a pre-key (KTi+KO) which has been computed before from said auxiliary key (KO) and from the first subcomponent (KTi); means for calculating said first sub-component (KTi) from the pre-key (KTi+KO) and from the auxiliary key (KO) and storing the said component in said erasable, programmable read-only memory (EEPROM), after mutual authentication between the security module and the initialization card (IK) and after transmission of the prekey into the security module.
Claim 4
Dependent Claim
22 words
The data exchange system according to claim 1 or 2, wherein said security module is fashioned as a plug-in security card (SK).
Claim 5
Independent Claim
69 words
A method of protecting access to a data exchange system for which use of a secret key is necessary, comprising the steps of: dividing said secret key into two components (KTi and KT'i), storing one of said components in a security module; maintaining the other component outside of said security module; and supplying said other component to logic means in said security module for generating the complete secret key.
Claim 6
Independent Claim
69 words
A method of protecting access to a data exchange system for which use of a secret key is necessary, comprising the steps of: dividing said secret key into two components (KTi and KT'i), storing one of said components in a security module; maintaining the other component outside of said security module; and supplying said other component to logic means in said security module for generating the complete secret key.
Claim 7
Dependent Claim
54 words
The method according to claim 4, including the steps of: using an initialization card to store a pre-key calculated from said one component and from an auxiliary key; calculating said one component from said pre-key and from said auxiliary key, stored in said security module; and storing said one component in the security module.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-20 | 1994-02-19 | 1994-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-20 | 1998-02-19 | 1998-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-20 | 2002-02-19 | 2002-08-21 | $7700.00 | Window Closed / Lapsed |