System for the provision of a reticulated utility.

INTRODUCTION ANO 8ACKGR0IIMD

THIS invention relates to of a reticulated utility a system for the provision such as, for example, .· u - _o 1 - - u• -½ · · J } * ^w I x, t '-A k. C U V development of the system described in the ADplicant's South African patent application 90/3939.

In the Applicant's Patent application 90/3939 there is described a system for the provision of a reticulated utility to utility users, of the type wherein:

<td> each uti11ty</td><td colspan="2"> user is provided</td><td> with</td><td> a control</td>

<td> device for</td><td> · . .. ₃</td><td> e use</td><td> of the</td><td> utility by</td>

<td colspan="2"> the respective user, the</td><td colspan="3"> control device being</td>

<td> capable of</td><td> accepti ng</td><td> a</td><td> c red i t</td><td> for the</td>

<td> provision of</td><td> the utility</td><td> and</td><td> being</td><td> operative</td>

<td> to reduce</td><td> the credit</td><td colspan="2"> according to</td><td> the amount</td>

of utility used;

each control device is associated with a device identity code distinguishing that

<img file="AP322A_D0001.tif" />

AP Ο Ο Ο 3 2 2 control device fro in other control devices in the system, is provided with data entry means thereby encrypted data can be entered into the control device, and is 'u r the r provided with

<td> d P n r y p *. ί o n</td><td> m “ a η η ' n</td><td> r</td><td> *er-ynfinn 'he data</td><td> so</td>

<td> entered;</td><td></td><td></td><td></td><td></td>

<td> as part of</td><td> a payment</td><td colspan="2"> transaction in respect</td><td> o f</td>

<td> a p a r t i c u 1</td><td> ar contro</td><td> I d</td><td> evice, a payment code</td><td> i s</td>

<td> generated ,</td><td> enc rypted</td><td> 9</td><td> and issued in</td><td> the</td>

<td> e n c'voted</td><td> form. t</td><td> he</td><td> oavment code being</td><td> a</td>

<td> function of</td><td> at least</td><td> the</td><td colspan="2"> device identity code</td>

<td> of the</td><td> res pecti ve</td><td></td><td> control device and</td><td> a</td>

transaction code distinguishing the respective payment transaction from previous payment transactions for the control device; and the encrypted payment code is entered via the data entry means into the control device, decrypted by the decryption means, the device identity code and the transaction code extracted f^rom the decrypted payment code and the transaction code saved by the control device 'or future reference, and, provided the extracted transaction code does not match a previously saved transaction coda and the extracted device identity code matches the

<img file="AP322A_D0002.tif" />

BAD ORIGINAL

Η device identity code of the respective control device, the control device is credited with an

3ίouπt of the utility.

Such a system is herein referred as a system che &lt;i nd described. It requires each control device to nave a memory arrangement for keeping a •'ecord of the transaction codes of previous payment codes *&gt;« ·» Λ 1

Tk η memory arrangement should be large enough to keep a record :^c all the transaction codes likely to be encountered during the service life of the control device. Electronic memory devices are expensive, the cost increasing with memory capacity. It is an object of cne present invention to provide a system of the kind described, wherein efficient use is made of a memory space for keeping a record of the transaction codes.

SUMMARY 3F INVENTION according to the present invention there is provided a system of the kind described, wherein each control device comprises a plurality of memory cells for

<img file="AP322A_D0003.tif" />

AP Ο Ο Ο 3 2 2 the transaction codes of payment transactions; ./herein each of the cells being defined by an unique address; ./herein eacn issuable transaction cede corresponds to keeping a record of previously accepted on;

the cells; and the address o* a - e s p ec t i v* wnerein a transaction code is recorded by changing the state of the cell defined by the memory address corresponding to that transaction code.

The cells may be dual logical state prereraDly arranged in the ^forn of an array may comprise at least one EEPROM chi cel Is and array .

P.

are

The

This means that only one cell or bit of memory soace is required for each transaction code. For example, 1 Kbyte of memory would be able to keep a record of 8 x 1024 = 3192 transaction codes. Furthermore, different encrypted payment codes can be entered in any desired sequence, and not necessarily in the same sequence as that in which the corresponding payment transaction were effected.

The transaction code is preferably recorded by changing the ¹ o g i c a 1 state of the cell defined by the memory address correspond!ng to that transaction code

<img file="AP322A_D0004.tif" />

t · · ⁴ from 3 1 ο a i c fti ah state to a 1 ο a i c low state

Also i n c 1 j d e d within the s c ο o e of tne present invention is a control device for metering use of a

- .1 of accepting a credit for the provision of the utility and being ooerative to •'educe the credit according to the amount of utility used, the control device comorising data entry means whereby an encrypted payment code which is a function of at least an identity code for the control device and a transaction code can be entered into the control device; decryption means for decrypting the data a x t.- a c t i η a the identity code and the transaction code; memory means wherein data regarding previously accepted transaction codes and the identity code for the control device are recorded, the control device being capable of accepting a credit for the provision of the utility only if the extracted transaction code does not natch a previously accepted transaction code and the ext-'acted identity code matches the recorded

<img file="AP322A_D0005.tif" />

AP Ο Ο Ο 3 2 2 identity code for the control device; the device being character)sed in that said memory means comprises a plurality o * memory cells for keeping record of previously accepted oayment codes; in that £ d C u 0 7 C »1 ΰ v d 1 1 S 0 tj i il y &lt;u C 7 i ii 6 U v j &lt;□ u ί I i U ti ά J d Γ fi $ s ΐ in that each issuable transaction code corresponds to the address of a respective one of the cells; and in that a used transaction code is recorded by changing the state of the cell defined by the memory address C Ο Γ f c 5 pO Π J i ii y 1 0 , ii ά ί ι» , ά ιι S ά C t ύ π C ύ u c · of: issuing an also extends to a method of controlling, by means of a control device, provision of a predetermined amount of a reticulated utility. The method comprises the steps encrypted payment code being a function of at least an identity code for the control device and a transaction code, each issuable transaction code corresροnding to an address for a memory cell in the control device; entering the encrypted payment code into the control device; causing the control device to decrypt the encrypted payment code and to extract the identity code and the transaction code therefrom;

-7 bad ORIGINAL g crediting the control device utility only if the extracted identity code matches an identity code saved in the device and if the state of the ceil associated •vith the transaction z o a e eorresoonds to a oredetermined state : and thereafter changing the state o+ said cell tn another state.

with an amount of the

BRIEF DESCRIPTION OF THE DRAWING

The invention will now ^cu r t h e r he described, hy way of example only, with reference to the accompanying diagram wherein:

figure 1 is a block schematic of a system in accordance with the invention, for the orovision of a utility in the form of electricity, to electricity users; and figure 2 is a '“presentation of an array of memory cells, associated addresses for the cells and corresponding transaction codes.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Each electricity user is provided with a control device 10 'only one of which is shown). The term electricity user is intended to denote, for exanDle, a domestic premises which is connected to a reticulated mains electricity network. The control

<img file="AP322A_D0006.tif" />

AP Ο Ο Ο 3 2 2 device comorises metering leans ^czr metering the consumption of electricity by the user, and a circuit breaker (not shown) for interrupting the supply of electricity to the user. ^The control device further comprises microprocessor oasea circuitry (aiso not shown) whicn is capable of accepting a credit for the supply of electricity, and is operative in response to the metering means to reduce the credit according to the amount of electricity consumed by the user. The ,n i c ro μ r oc e s ίο ι ha^cu circuitry is further operative to trip the circuit breaker when the amount

<td> T _{Λ Λ} x 4 u i 2 ι c u, υ ι ι</td><td> « 4 X . . » &gt;</td><td> cred i</td><td> ted has be</td><td> e n used.</td><td></td><td></td>

<td> To enable</td><td> the</td><td colspan="2"> microprocessor</td><td> based ci rcui try</td><td> to</td><td> be</td>

<td> credited</td><td> fo r</td><td> the</td><td> supply of</td><td> electricity, the</td><td colspan="2"> control</td>

<td> device 13</td><td colspan="2"> further</td><td> comprises</td><td> a key-pad 12</td><td> and</td><td> a</td>

<td> dec rypte r</td><td> 14.</td><td> An</td><td> encrypted</td><td> payment code</td><td colspan="2"> is keyed</td>

<td> manually</td><td> into</td><td> the</td><td> key-pad</td><td> 12, decrypted</td><td> by</td><td> the</td>

<td> decrypter</td><td> 14,</td><td> and ,</td><td> provided</td><td colspan="2"> certain cond i tions</td><td> are</td>

met (as described hereunder) a register (not shown) forming part of the microprocessor based circuitry incremented, the increment representing a credit for the supply of the amount of electricity paid 'or, •f'nen electricity is used, the register is decremented

<img file="AP322A_D0007.tif" />

<img file="AP322A_D0008.tif" />

ⁿ · Μ Λ according to the amount of electricity used.

The device 19 further comprises a non-volatile transaction history memory ar-ay in the ^corm of at least one -. 2 P R 0 Ί chip 1 5 .

When the control device 19 is first installed all the memory cells of the EEPROM 15 will be set to 1 (a logical high state).

The control device 19 is associated with a device identity code which distinguishes the control device from other control devices in the system. The device identity code has to be known to a person who purchases electricity for the particular electricity

J $ 9 P ·

Electricity can be paid for at any one of a of vending stations 15 (only two of which are each station being connected to a central station 18 via a communication link 29. Each station comprises an encrypter 22 and a printer number shown ), master vending .

oayment transaction takes place as follows.

When

<img file="AP322A_D0009.tif" />

AP Ο Ο Ο 3 2 2 device identity code and tne amount of electricity being purchased, and pays for it. A cashier at the vending station '5 &lt;eys the specified device identity code and the amount of electricity

0u i' C ιi ά S e ΰ ί Γι C Ο ά .&lt;e / 50e /'u , automatically generates particular transaction, ι c ( c .ιό i ’i4 station then transaction code for that tne transaction code distinguishing the payment transaction from previous payment transactions for the control device in question. The vending station further generates a payment code which is a function of the device identity code, the transaction code, and an amount code corresponding to the amount of electricity purccased.

The payment code is then encrypted by the encrypter 22 to generate an encrypted payment code. The printer 24 prints the encrypted payment code onto a paper ticket 26 whicn is handed to the purchaser. Payment could also be mailed to the vending station and the ticket mailed to the purchaser. The central master station 13 '5 updated so that none of the vending stations IS can subsequently issue an encrypted payment code for the same control device,

<img file="AP322A_D0010.tif" />

The encryoted payment code issued station can now be entered manually into the control device 13.

the control device then operates by the vending via the key-pad e decrypter 14 of to decrypt the

<td> - ‘ ~ ‘ J</td><td> n □ -T t* * - -</td><td> a / q »» r “· j · * ·</td><td> *· - a Η o ·.&lt; b o .* o . ι -. n - * ^w - * &gt; . ·- — r -</td><td>¹ Η ο n + ν» .λ 1 Ί a ι/ ] * o</td>

<td colspan="2"> extracts</td><td> the dev</td><td> ice identity code,</td><td> tiie transaction</td>

<td> code ,</td><td colspan="2"> and the</td><td> amount code from the</td><td> decrypted payment</td>

<td> code .</td><td></td><td></td><td></td><td></td>

<td> Once</td><td> the</td><td> device</td><td> identity code and</td><td> the transaction</td>

<td> code</td><td colspan="2"> have been</td><td> extracted from the</td><td> decrypted payment</td>

<td> code ,</td><td> the</td><td> control</td><td> device verifies the</td><td> device identity</td>

<td> code</td><td> and</td><td colspan="2"> the transaction code.</td><td></td>

Verification of the device identity code is effected by checking if the device identity code extracted

<td> from</td><td> the</td><td> de c ryp ted</td><td colspan="2"> payment</td><td> code</td><td> matches</td><td> the device</td>

<td> i d e n t i</td><td> ty</td><td> code of</td><td> the</td><td> device</td><td> 1 0</td><td> into</td><td> which the</td>

<td> enc ryp</td><td> ted</td><td> payme n t</td><td> code</td><td> has</td><td> been</td><td> entered</td><td> . If they</td>

match, the verification is successful. If they do not match the verification is unsuccessful.

As represented in ^rigure 2 each issuable transaction code corresponds to an address ./hich 'identifies one

<img file="AP322A_D0011.tif" />

AP Ο Ο Ο 3 2 2 single-bit (memory cell) in the ESPROM array 15.

<td> Veri fication</td><td> o f</td><td> the</td><td> transaction</td><td> code is effected by</td>

<td> checking ·’ f</td><td> the</td><td> 1</td><td> O Q J* '/ r O 1 1</td><td> at the address</td>

<td> correspond!ng</td><td> to</td><td> the</td><td> transaction</td><td> code is set to 1</td>

<td> (H i gn) or j (</td><td> uOw ) .</td><td> i f</td><td> i C t 3 3 c C</td><td> -- * λ. - - ; - , _x vU ., C * l ι 3 )3 Q Π</td>

<td> indication t</td><td> hat</td><td> that</td><td> particular</td><td> transaction code has</td>

not previously been recorded, and tne verification of the transaction code is thus successful. If it is set to 0, this is an indication that that particular cranSdction &lt;„ o J e 11 a s — c ΰ &gt; e c o r d e u previously, and the verification of the transaction code is thus unsuccessful .

If verification of either the extracted device identity code or the transaction code is unsuccessful, the payment code is rejected. If, on the other hand, verification of both the extracted device identity code and the transaction code is successful, the transaction code is recorded in the EEPROM ;5 by setting the cell at the corresponding address to 0. Furthermore, the register referred to earlier is incremented by an amount corresponding to the amount code, thereby crediting the control device ^r'or the provision of electricity to the respective

<img file="AP322A_D0012.tif" />

h. . »

To improve the security of the system, the encryption/decryption algorithm used may be such that the memory locations in the memory array correspond unidirectiona11y to the transaction codes in the example, using a mathematical trap-door function.

It will be appreciated that there may be more than one of the memory arrays, which will make it possible to cater for different groups of transaction codes, each group of transaction codes being recorded in a corresponding one of the memory arrays.

<td> - +· ,&lt;' ..... J 1 ’j</td><td> her be a p p r ? c</td><td> iat ? d that there</td><td> are many</td>

<td> variations in</td><td> detai 1 on the</td><td> sys tern , con trol</td><td> device</td>

<td> and method</td><td> according to</td><td> the invention</td><td> without</td>

<td> departing from</td><td> the scope and</td><td> spirit of the</td><td> appended</td>

claims.