STS Primer
WHAT IS STS?
Standard Transfer Specification (STS) is a secure message system for carrying information between a point-of-sale and a meter, and is currently finding wide application in electricity metering and payment systems. STS is not limited to this application (see the section: Future enhancements), but because of the wide interest in this area, this document describes the electricity application.
STS has become recognized as the only globally accepted open standard for prepayment systems, ensuring inter-operability between system components from different vendors. STS technology is currently used in 84 countries around the world. The application of the technology is licensed through the STS Association, thus ensuring that the appropriate encryption key management practices are applied to protect the security of prepayment transactions.
The STS has been adopted by IEC as IEC 62055 parts -41 and -51 as the international standard for prepaid electric metering.
WHY USE STS?
Critical to the successful operation of any payment system are the issues of security and inter-operability of equipment supplied by different manufacturers. STS fully addresses these key issues:
Security
Security issues are of prime importance to the utility supplier and the consumer. The use of the STS standard prevents:
▪ Fraudulent generation of tokens from hit and miss attempts at entering the correct number;
▪ Fraudulent generation of tokens from a stolen vending station;
▪ Fraudulent generation of tokens from legitimate vending stations outside of the utility's area;
▪ Fraudulent use of tokens which have already been used;
▪ Tampering of legitimate tokens e.g. to change the value
STS provides the facility of generating (e.g. credit transfer) tokens which can only be used by the intended meter, and furthermore in the case of credit tokens, can only be used once in that meter.
In order to achieve the above security, the standard defines the following:
▪ the use of advanced encryption techniques, which are at all times hidden from the consumer -the system is easy to use.
▪ the use of very secure key management procedures, including the manner in which keys are generated and transported.
▪ Required functionality at both the vending station and the meter.
Inter-operability
Users have long struggled with various systems performing the same or similar functions but which are not compatible with one another, and with components of these systems which are not inter-operable with those from different manufacturers or suppliers.
STS is an open system specification which defines transfer tokens which may be generated at a vending system from any one of a number of suppliers, and used in STS compliant meters from any one of a number of suppliers. The functionality at the vending station and the response of meters to certain transfer numbers is also specified in order to achieve inter-operability. This allows utilities to mix and match equipment from suppliers of their choice.
The Association ensures inter-operability between system components from different manufacturers, by:
▪ Ensuring that manufacturing members make encryption keys available to other manufacturers at the request of the utility using the equipment;
▪ Accrediting and maintaining a list of equipment test laboratories which ensure correct STS functionality of equipment;
▪ Ensuring consistent manufacturer identity codes and meter serial numbers
Security Policy Control
The STS Association carries out the necessary functions to assure the security of STS systems. These include the following:
▪ Obtaining the agreement of manufacturers on rules regarding the handling of confidential information and procedures
▪ Approving equipment and processes for generating and transferring encryption keys
New Applications
In addition to the electricity utility application discussed above, STS can easily be expanded to include other utilities such as gas and water. STS transfer numbers, rather than being hand carried, may be transmitted using various communication standards such as DLMS ‡.
* NRS - The National Rationalisation of Standards body is responsible for co-ordinating user requirements on a national scale prior to these being tabled as national specifications.
† IEC - The International Electrotechnical Commission is an international body which generates standards relating to electrical systems - It's Technical committee TC13 is responsible for electricity metering, and working group WG15 for payment systems.
‡ DLMS - 'Device Language Message Specification' is a protocol allowing meters and meter system components from different manufacturers to communicate with one another.
Standard Transfer Specification (STS) is a secure message system for carrying information between a point-of-sale and a meter, and is currently finding wide application in electricity metering and payment systems. STS is not limited to this application (see the section: Future enhancements), but because of the wide interest in this area, this document describes the electricity application.
STS has become recognized as the only globally accepted open standard for prepayment systems, ensuring inter-operability between system components from different vendors. STS technology is currently used in 84 countries around the world. The application of the technology is licensed through the STS Association, thus ensuring that the appropriate encryption key management practices are applied to protect the security of prepayment transactions.
The STS has been adopted by IEC as IEC 62055 parts -41 and -51 as the international standard for prepaid electric metering.
WHY USE STS?
Critical to the successful operation of any payment system are the issues of security and inter-operability of equipment supplied by different manufacturers. STS fully addresses these key issues:
Security
Security issues are of prime importance to the utility supplier and the consumer. The use of the STS standard prevents:
▪ Fraudulent generation of tokens from hit and miss attempts at entering the correct number;
▪ Fraudulent generation of tokens from a stolen vending station;
▪ Fraudulent generation of tokens from legitimate vending stations outside of the utility's area;
▪ Fraudulent use of tokens which have already been used;
▪ Tampering of legitimate tokens e.g. to change the value
STS provides the facility of generating (e.g. credit transfer) tokens which can only be used by the intended meter, and furthermore in the case of credit tokens, can only be used once in that meter.
In order to achieve the above security, the standard defines the following:
▪ the use of advanced encryption techniques, which are at all times hidden from the consumer -the system is easy to use.
▪ the use of very secure key management procedures, including the manner in which keys are generated and transported.
▪ Required functionality at both the vending station and the meter.
Inter-operability
Users have long struggled with various systems performing the same or similar functions but which are not compatible with one another, and with components of these systems which are not inter-operable with those from different manufacturers or suppliers.
STS is an open system specification which defines transfer tokens which may be generated at a vending system from any one of a number of suppliers, and used in STS compliant meters from any one of a number of suppliers. The functionality at the vending station and the response of meters to certain transfer numbers is also specified in order to achieve inter-operability. This allows utilities to mix and match equipment from suppliers of their choice.
The Association ensures inter-operability between system components from different manufacturers, by:
▪ Ensuring that manufacturing members make encryption keys available to other manufacturers at the request of the utility using the equipment;
▪ Accrediting and maintaining a list of equipment test laboratories which ensure correct STS functionality of equipment;
▪ Ensuring consistent manufacturer identity codes and meter serial numbers
Security Policy Control
The STS Association carries out the necessary functions to assure the security of STS systems. These include the following:
▪ Obtaining the agreement of manufacturers on rules regarding the handling of confidential information and procedures
▪ Approving equipment and processes for generating and transferring encryption keys
New Applications
In addition to the electricity utility application discussed above, STS can easily be expanded to include other utilities such as gas and water. STS transfer numbers, rather than being hand carried, may be transmitted using various communication standards such as DLMS ‡.
* NRS - The National Rationalisation of Standards body is responsible for co-ordinating user requirements on a national scale prior to these being tabled as national specifications.
† IEC - The International Electrotechnical Commission is an international body which generates standards relating to electrical systems - It's Technical committee TC13 is responsible for electricity metering, and working group WG15 for payment systems.
‡ DLMS - 'Device Language Message Specification' is a protocol allowing meters and meter system components from different manufacturers to communicate with one another.