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Prepaid Electricity token meters: The technical aspects involved

On the previous article,we looked at the basis of the prepaid electricity metering technology. The STS standard was discussed to be the main technology in prepaid electricity service. I also introduced the process that is involved in token generation. In this article I shall discuss hoe the tokens are actually generated.

They are two main processes that are involved in the token generation. The first step is the generation of a decoder key and the second step is the use of the generated decoder key in the first step and an encryption process to generate a token. These steps are discussed below.

Step 1. Generation of the decoder key.

A 128 bit or a 160 bit key is first used to generate a vending key that unique to every service provider. The decoder key is thus generated from this vending key. This decoder key will be implemented by the Hardware Security Modules (HSMs) based on your meter.

Decoder key generation process

Step 2. Encryption process.

Once the decoder key has been generated, it is used by an encryption algorithm to generate a 64 bit data block into 20 digit prepaid token number. This data block consists of the actual desired values of the token(class and sub class).,the amount of the purchased units and the the time the units were bought for identification.

Token generation process.

Once the token has been generated it is sent to the user via an sms. When the user enters the 20 digit token code into the meter,it is decoded to give the number of electrical units purchased on kWh. This ends the token generation process.

Token acquisition process by customer.

Content created and supplied by: ThirdBucaneer (via Opera News )

HSMs Hardware Security Modules STS


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