Cryptography – Key management – Having particular key generator
Patent
1994-07-13
1998-03-31
Cain, David C.
Cryptography
Key management
Having particular key generator
380 23, 235380, H04K 100
Patent
active
057347220
DESCRIPTION:
BRIEF SUMMARY
This paper deals with a portable private data base in pocketsize format outwardly resembling a pocket calculator and combining a number of inventive characteristics in order to obtain a few important results: Replacement of on-line transactions by secure off-line point of sale transactions. The device should have a long working life. The user should have access to his data at any time without the cooperation of a terminal. During a transaction, the device shall remain handheld to avoid the delays associated with machine-fed read positions.
Insofar as this patent application is concerned we shall refer to said private pocketsize data base as a "travel pass", because of the term's brevity and the expected outstanding utility it may come to have for mass transportation applications. Some of the ideas underlying the present concept of a n "electronic travel pass" have already been defined by the present author, especially in U.S. Pat. No 4,661,691 (Proximity Data Transfer System) or U.S. Pat. No. 4,499,556 which deals with the problem of security for long-life cards, or U.S. Pat. No. 4,906,828 which describes data entry on the card itself, and U.S. Pat. No. 4,906,828 which describes a simple scrambling circuit for protecting the secrecy of the data interchanged between a card and a transaction Reader.
Further inventive effort was necessary to provide a "travel pass" with greater data transfer speed; to protect the integrity of the data in face of exterior electric noise or interference; to enlarge its usefulness; to enable the owner of the "travel pass" to select his/her secret PIN and to change it at any time, without the assistance from a second person or office; to convert a travel pass which normally can only communicate with a terminal at close proximity, into a radio-responsive card capable of passing on its serial number or account number over a distance of several feet.
Descriptions of these various aspects will now be given with the aid of illustrations and drawings, wherein
FIG. 1 is a block diagram of stationary apparatus forming a part of the invention.
FIG. 1a is a front view of the Smart Contactless Security Key which may be used with the invention.
FIG. 1b shows a card with two embedded capacitive antenna plates and a data retrieval circuit associated with them.
FIG. 1c and FIG. 1d show an equivalent circuit explaining data transfer by impedance changes
FIG. 2 shows an example of the wave forms at different parts of the circuit.
FIG. 3 shows portions of the signal emitter circuit of the Card READER unit which is largely a mirror image of the circuit of FIG. 1b.
FIGS. 3a, 3b and 3c are details of FIG. 3.
FIG. 3d is a modified form of data transfer circuitry of FIGS. 3a, 3b and 3c.
FIG. 4 indicates the modifications of the FIG. 1 circuitry when in place of the capacitor antenna a flat spiral coil is laid into the card and Reader respectively.
FIG. 5 illustrates the basic schematics of a "travel pass" combined with a modified form of the FIG. 1 circuit.
FIG. 6 shows a Reader and proximity-operated Card or "travel pass" with a a very simple data retrieval circuit connected to a Motorola CMOS microcomputer. chip. In this design, the square pulses imputted in FIG. 1, are now replaced by VHF sin waves applied to the same twin capacitor plates in antiphase.
FIG. 7 shows a string of .alpha. sin waves used for data modulation, and the string of .beta. sin waves used for producing timing pulses.
FIG. 8 represents an example of logic levels transferred to the "travel pass" as data and logic levels applied to the "travel pass" computer chip as clock pulses.
FIG. 9 shows again the clock pulses (CK) and the (.alpha.-3) output from the differential amplifier representing data transferred from the card to the Reader.
FIG. 10 shows two spiral coils connected in phase, to satisfy the condition for cooperating with short-distance proximity Readers; they are connected via switches in such a manner that they may work in anti-phase with the Reader emitters, and that makes them suitable for working in phase with a radi
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patent: 5485520 (1996-01-01), Chaum et al.
patent: 5532689 (1996-07-01), Bueno
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