Definitions

• the present invention relates to the supply of goods and/or services. More particularly, the present invention relates to the supply of utilities such as gas, electricity, water, heat or cable television.
• the primary use of the present invention is for the supply of gas or electricity
• the supply of gas or electricity is conventionally monitored by a meter.
• meters were either simply an accumulation of the amount of gas or electricity used which required the meter to be read periodically so that the customer could be billed or else the meter was a coin released device.
• coin released devices were susceptible to damage by thieves stealing the coins and consequently, more recently, it has become common to have a pre-payment meter which required the entry of information into the meter rather than the insertion of a coin to supply the electricity.
• EP-A-0420466 proposed an alternative to this basic principle by providing a meter with a keypad and arranging for the customer to be given a discernable alpha-numeric code in exchange for handing over cash at a central location.
• the code supplied to the customer is based on the identification number of the electricity meter concerned and the amount of money which has been handed over by the customer.
• the present invention is based on the encoding means and the decoding means at the user's premises utilizing the same key, which key is changed for every transaction.
• the plain text message is in the form of a data encryption ' standard code which can be "read” by the meter and checked for accuracy by appropriate signal processing.
• FIG. 1 shows schematically a system according to the present invention
• Fig 2 is a diagrammatic representation of message according to the present invention.
• the present invention is based on the Calmu technology which has been utilized by the applicants for many years and which includes, inter alia, an electricity meter provided with a keypad and display.
• the encrypted message is a 20 digit alpha- numeric code which is printed out on a slip of paper which is then handed to the customer for him to enter into his meter 21 using the keypad 22 associated therewith.
• the key utilized to encrypt the plain text message is changed with every transaction so that each plain text message is encrypted using the latest key in a key sequence.
• Each meter is provided with a key sequence and only a meter utilizing the appropriate key can decrypt the message and utilize the part of the message indicative of the amount of money which in turn is indicative of the amount of electricity which should be permitted to be used.
• the key utilized by the central computer 12 to encrypt the plain text message must be the same as that used by the meter 21 to decode the message. This can be achieved in a number of ways depending upon the degree of security required. Basically, one is seeking to ensure that the same 20 digit encoded message cannot be used again by the same meter nor be applied to another meter in order to provide credit to that other meter.
• One way of synchronising the keys is for the central computer and the meter to utilize the same algorithm for generating keys and "seeding" the algorithms with the same start key, for example depending on the number of times the meter has been incremented with cash payments.
• the central computer will know this as also will the meter without there being any need to signal this in the plain text message.
• Such a method means that the same coded text message will not result in a proper decode by the same meter because the meter will move to the next key which is different to that used to produce the plain text message. Also, it is unlikely that even a different meter with the same algorithm will be in the same position in the sequence determined by the algorithm as the meter in which the message was used originally, again resulting in an improper decode.
• the correctness of the decode can be checked in any one of a number of different ways, eg a check digit or sequence.
• the preferred form of message is a 20 digit number each number being a decimal number of 0 to 9.
• the underlying message is in fact a data encryption standard code which in this example is a 64 bit code formed as two blocks of 32 bits.
• Figure 2 is a diagrammatic representation of the information which will be contained in the encoded message and is not intended to indicate which particular digits represent information relating to specific parts of the original 64 bit message.
• the 20 digit message contains control bits, information relating to the utility being metered, the source of the utility, the amount of money being credited, the tariff and also authentication bits.
• the appropriate bits of the original plain text message appear in predefined positions within the message and consequently the meter will go through a logical checking sequence after decoding a message to ensure that the decoding has resulted in the correct locations receiving appropriate information.
• One way of achieving this is to have an account sequence number included in the authentication portion of the message which can be checked against previous account sequence numbers temporarily stored in the meter and overwritten when a correct decode is signalled.
• each encoded message is a 20 digit alpha-numeric sequence and in this case the first 20 digit sequence is used to signal to the meter that one or more additional 20 digit sequences are to be expected.
• the 64 bit DES code is divided into two blocks of 32 bits. The first number in decimal of each group is used as the redundant bit and it is determined that if the decimal value of this bit is less than 5 if encoded directly, then this signals that additional information is present. It is therefore proposed to add 5 (or not) to each of these decimal values in order to carry an un-encoded message with four possible values (00, 01, 10, 11). One of these values (eg 11) is used to indicate that there is another message expected.
• One of the other logic values could be used to identify that the message is for another utility which would be vital when a different key is essential for each utility, and this must be known before attempting a decode.
• the tenth and twentieth digit is examined and if greater than 5, the appropriate flags are set and the value of the tenth and twentieth digit has 5 deducted from it.
• the continuity flag is set to the value 1 1
• the amount section of the code is used to indicate a tariff change and not a credit transfer.
• the scheme then requires another 20 decimal digit message to be received in order to indicate the amount of credit transferred at the new rate which is indicated by the tariff code portion of the second 20 digit message. If the 20 digit messages are entered in the wrong order, the credit transfer block will not be valid since it will be carrying the wrong tariff code.
• the credit transfer block does not carry any extra bits if it is for an electricity account. The customer then has to enter the tariff change block before he can enter a valid credit transfer block.
• each 20 digit block actually represents a 64 bit message.
• the customer While it is preferable for the customer to attend a vending location, it is also possible to provide the encrypted message to the customer in other ways, eg by telephone, via the Internet or interactive television.

Landscapes

• Beverage Vending Machines With Cups, And Gas Or Electricity Vending Machines (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=32039809

Family Applications (1)

Country Status (2)

Citations (2)

Family Cites Families (4)

• 2001
  • 2001-03-14 EP EP01911924A patent/EP1410345A1/de not_active Withdrawn
  • 2001-03-14 AU AU2001240846A patent/AU2001240846B2/en not_active Expired

Patent Citations (2)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events