CA2244126C - Procedure and device for loading input data into an algorithm during authentication - Google Patents

Procedure and device for loading input data into an algorithm during authentication Download PDF

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Publication number
CA2244126C
CA2244126C CA002244126A CA2244126A CA2244126C CA 2244126 C CA2244126 C CA 2244126C CA 002244126 A CA002244126 A CA 002244126A CA 2244126 A CA2244126 A CA 2244126A CA 2244126 C CA2244126 C CA 2244126C
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Canada
Prior art keywords
input data
shift register
loading
downstream
feedback
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Expired - Lifetime
Application number
CA002244126A
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French (fr)
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CA2244126A1 (en
Inventor
Frank Schaefer-Lorinser
Alfred Scheerhorn
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Deutsche Telekom AG
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Deutsche Telekom AG
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Filing date
Publication date
Priority claimed from DE19622533A external-priority patent/DE19622533A1/en
Application filed by Deutsche Telekom AG filed Critical Deutsche Telekom AG
Publication of CA2244126A1 publication Critical patent/CA2244126A1/en
Application granted granted Critical
Publication of CA2244126C publication Critical patent/CA2244126C/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07FCOIN-FREED OR LIKE APPARATUS
    • G07F7/00Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus
    • G07F7/08Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by coded identity card or credit card or other personal identification means
    • G07F7/10Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by coded identity card or credit card or other personal identification means together with a coded signal, e.g. in the form of personal identification information, like personal identification number [PIN] or biometric data
    • G07F7/1008Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06QINFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q20/00Payment architectures, schemes or protocols
    • G06Q20/30Payment architectures, schemes or protocols characterised by the use of specific devices or networks
    • G06Q20/34Payment architectures, schemes or protocols characterised by the use of specific devices or networks using cards, e.g. integrated circuit [IC] cards or magnetic cards
    • G06Q20/341Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06QINFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q20/00Payment architectures, schemes or protocols
    • G06Q20/38Payment protocols; Details thereof
    • G06Q20/40Authorisation, e.g. identification of payer or payee, verification of customer or shop credentials; Review and approval of payers, e.g. check credit lines or negative lists
    • G06Q20/409Device specific authentication in transaction processing
    • G06Q20/4097Device specific authentication in transaction processing using mutual authentication between devices and transaction partners
    • G06Q20/40975Device specific authentication in transaction processing using mutual authentication between devices and transaction partners using encryption therefor
    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07FCOIN-FREED OR LIKE APPARATUS
    • G07F7/00Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus
    • G07F7/08Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by coded identity card or credit card or other personal identification means
    • G07F7/0866Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by coded identity card or credit card or other personal identification means by active credit-cards adapted therefor
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/32Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
    • H04L9/321Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials involving a third party or a trusted authority
    • H04L9/3213Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials involving a third party or a trusted authority using tickets or tokens, e.g. Kerberos
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/32Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
    • H04L9/3236Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials using cryptographic hash functions
    • H04L9/3242Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials using cryptographic hash functions involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L2209/00Additional information or applications relating to cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
    • H04L2209/56Financial cryptography, e.g. electronic payment or e-cash

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Business, Economics & Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Accounting & Taxation (AREA)
  • General Business, Economics & Management (AREA)
  • Strategic Management (AREA)
  • Theoretical Computer Science (AREA)
  • Signal Processing (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Finance (AREA)
  • Power Engineering (AREA)
  • Storage Device Security (AREA)
  • Financial Or Insurance-Related Operations Such As Payment And Settlement (AREA)

Abstract

2.1 The problem with security in paying with chip cards is the loading of input data into an algorithm during authentication.
2.2 Separating the data blocks and switching; an additional feedback after the post-connected counters on and off at preselected times (number of clock pulses) helps to improve the security of debited and credited data.
2.3 The invention can be used for all authentication procedures where chip cards are used.

Description

28.030-19 Procedure and device used to load input data during authentication into an algorithm Description:
The invention relates to a procedure as described in detail in claim 1, and to a device of the kind defined in claim 9. Several procedures of this kind are known and are used for various kinds of electronic cash cards, while the devices are digital circuits for chips according to EP 0 616 429 A1.
Procedures of the kind referred to here are, for example, known from ETSI D/EN/TE 090114, Terminal Equipment (TE) Requirements for IC cards and terminals for telecommunication use, Part 4 - Payment methods, version 4, of 7 February 1992, and from the European patent application 0 605 070.
In addition to telephone cards with a defined value (starting credit), which are used for card phones, there are also electronic cash cards with similar functionality used for paying small amounts; these cash cards are of increasing importance. For the "pay with chip card" event, a card reader module and security module (SM) for verifying the card and the credit amount are integrated in the equipment.
EP 0 605 070 A2 also describes a procedure to transfer (credit and debit) money amounts to and from chip cards whereby overridable memory locations of a chip card are divided into at least two memory locations, one of which is used for debiting amounts (i.e. electronic cash card), similar to telephone cards, and the other one is used for crediting amounts, similar to a credit card. With the 28.030-19 normal security conditions applied, it is planned to transfer amounts between these two areas in order to refill the electronic cash card.
In order to avoid that unauthorized persons access a card reader and its built-in security module, and that specially protected, and consequently expensive (for the operator) dedicated lines have to be installed, a procedure (P95114) has been suggested whereby the operator of the card reader inserts a security module with chip card function into the card reader before any pay event. Tnlhen a cardholder inserts his or her electronic cash card into the card reader, data areas of the chip card are read out so that the card can be verified and the remaining credit amount be checked. Next, authentication with the security module, and one or several acceptance checks are carried out. Finally, the due amount or entered amount is debited to the cardholder's chip card using a security function, and added to the sum counter for money amounts in the security module. After such pay events, the counter setting of the security module is transmitted to a billing center.
The purpose of the invention is to increase the security of card readers for electronic cash cards with regard to manipulation and defects.
In accordance with one aspect of this invention, there is provided a process for loading input data into an algorithm during the authentication between chip cards with purse function and a security module, in which the card user has access to a stored credit balance and in which, at each transaction, the required cash amount or the cash amount entered by the card user is deducted from the chip card of the card user with the aid of a security function and the cash amounts are summated and stored in a summator for cash amounts of the security module, and in which a linear feedback shift register is used for the authentication algorithm, the nonlinear function of said shift register being cryptographically reinforced in conjunction with downstream counters, and in which input data, comprising a random number, a secret key and non-secret card data, are included in said algorithm, characterized in that the input data are divided into a plurality of blocks of data and in that, during the loading of the blocks into the linear feedback shift register, an additional further feedback circuit after the downstream counters is introduced into the shift register and is disconnected after a given number of clock pulse steps.
In accordance with another aspect of this invention, there is provided a device for loading input data into an algorithm during authentication using a cryptographic MAC function, consisting of a linear feedback shift register with a nonlinear feed forward function which picks off the shift register and, via a counter, influences the output of the shift register which is followed by a further counter, characterized in that, for use for the authentication algorithm, the circuit arrangement composed of the linear feedback shift register with downstream counters is cryptographically reinforced by an additional disconnectable nonlinear feedback circuit.
The invention, including its effects, advantages and fields of application, is described in detail by the following examples.
Authentication algorithms are typically used for identification security. In authentication procedures, however, other data plays a role in addition to the identity of chip cards and persons and possibly a security module (SM); the correctness of this other data must be ensured.
An authentication procedure can be used, for example, with non-secret card data (D) with a secret key (K) and a random number (R). For electronic cash cards, separate security functions are used for debits and credits, each of which is checked with a cryptographic checksum.
The invented procedure can be used to carry out debit and credit transactions using a cryptographic token, provided that authentication and cryptographic checksum are carried out via the counter setting and using a challenge/response procedure. In this case, a single challenge/response procedure, whereby only one random number is provided by the security module (SM) and only one response is calculated by the chip card, can prove both the identity (authentication) and the internal counter setting to the security module.
To achieve this, the variable input data, such as the counter setting and the random number, are initially processed internally with "keyed hash functions" - MAC
functions, whereby the card-specific secret key of the chip card is used as key. The tokens resulting from counter setting and random number can then be associated, for example, (in a perhaps cryptographically unsecure way) by XOR or a linear-feedback shift register, and subsequently be output, with protected data integrity, with a sufficient cryptographic function.
This procedure is of practical use insofar as the keyed hash functions, which are only used internally, do not have to meet particularly high requirements with regard to their security; also, relatively simple functions can be used since the results of these functions do not "leave" the chip card. Data manipulation, however, is effectively prevented.
5 The example for the invention assumes that a linear-feedback shift register (LFSR) with additional nonlinear function and post-connected counters is used:
0. Additional feedback circuits are applied after the post-connected counters in the LFSR.
1. Input data, consisting of the non-secret card data (D) and the secret key (K) is read into the LFSR while both the feedback of the LFSR and the additional feedback(s) are active.
2. A certain number of clock pulses occurs without input data being read in.
3. Input data consisting of the random number (R) is read in while both the feedback of the LFSR and the additional feedback(s) are active.
4. The additional feedback circuits are switched off, and the counters are reset, if necessary.
5. A certain number of clock pulses occurs, and during these pulses, output bits are generated according to the current counter settings.

Claims (14)

CLAIMS:
1. Process for loading input data into an algorithm during the authentication between chip cards with purse function and a security module, in which the card user has access to a stored credit balance and in which, at each transaction, the required cash amount or the cash amount entered by the card user is deducted from the chip card of the card user with the aid of a security function and the cash amounts are summated and stored in a summator for cash amounts of the security module, and in which a linear feedback shift register is used for the authentication algorithm, the nonlinear function of said shift register being cryptographically reinforced in conjunction with downstream counters, and in which input data, comprising a random number, a secret key and non-secret card data, are included in said algorithm, characterized in that the input data are divided into a plurality of blocks of data and in that, during the loading of the blocks into the linear feedback shift register, an additional further feedback circuit after the downstream counters is introduced into the shift register and is disconnected after a given number of clock pulse steps.
2. Process according to claim 1, characterized in that the card data with the secret key are introduced as a first block and the random number is introduced as a further block.
3. Process according to claims 1 and 2, characterized in that, during the loading phase of the input data, different counts are used than in the following phase after loading in of the input data for calculation of the authentication token.
4. Process according to claims 1 and 2, characterized in that the first downstream counter counts to 1.
5. Process according to claims 1 and 2, characterized in that the counters and the number of clock pulses to be executed are selected precisely such that the authentication token is calculated after a number of clock pulses fixed by other system conditions.
6. Process according to any one of claims 1 to 5, characterized in that the output of bits begins after all the input data have been loaded in.
7. Process according to any one of claims 1 to 6, characterized in that, between the loading in of the blocks from claim 1 and with the additional feedback being maintained, the entire circuit arrangement is clocked a few steps further without input data being loaded and before bits are output.
8. Process according to any one of claims 1 to 6, characterized in that, between the loading in of the blocks from claim 1 and after the additional feedback has been disconnected, the entire circuit arrangement is clocked a certain number of steps further without input data being loaded and before bits are output.
9. Device for loading input data into an algorithm during authentication using a cryptographic MAC function, consisting of a linear feedback shift register with a nonlinear feed forward function which picks off the shift register and, via a counter, influences the output of the shift register which is followed by a further counter, characterized in that, for use for the authentication algorithm, the circuit arrangement composed of the linear feedback shift register with downstream counters is cryptographically reinforced by an additional disconnectable nonlinear feedback circuit.
10. Device according to claim 9, characterized in that the additional feedback is picked off after the first downstream counter before a latch.
11. Device according to claim 9, characterized in that the additional feedback is picked off from a latch after the first downstream counter.
12. Device according to claim 9, characterized in that the additional feedback is picked off after the second downstream counter.
13. Device according to claim 9, characterized in that the additional feedback is in the form of an XOR sum of the pick-offs after the first downstream counter before a latch, from the latch after the first stream downstream counter and after the second downstream counter.
14. Device according to claim 9, characterized in that the counters are divided or reduced in size.
CA002244126A 1996-06-05 1997-06-04 Procedure and device for loading input data into an algorithm during authentication Expired - Lifetime CA2244126C (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19622533A DE19622533A1 (en) 1996-06-05 1996-06-05 Method and device for loading input data into an algorithm during authentication
DE19622533.7 1996-06-05
PCT/EP1997/002894 WO1997046983A2 (en) 1996-06-05 1997-06-04 Method and device for loading input data into an algorithm during authentication

Publications (2)

Publication Number Publication Date
CA2244126A1 CA2244126A1 (en) 1997-12-11
CA2244126C true CA2244126C (en) 2006-10-10

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CA002244126A Expired - Lifetime CA2244126C (en) 1996-06-05 1997-06-04 Procedure and device for loading input data into an algorithm during authentication

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