The document discusses the Standard Transfer Specification (STS), which is a secure message protocol for prepayment meters. It has been an industry standard since 1994 and is now also an IEC standard. There are approximately 5 million STS meters installed worldwide. The STS Association oversees the STS standard and provides key management and product certification services to support its use. The association is working to enhance the STS and integrate it further into the family of IEC 62055 standards for prepayment metering.

1. Prepayment Standard Transfer Specification: An IEC standard
Especificação de Transferência de Padrões de Pré Pagamento: Um padrão IEC
Don Taylor

2. Prepayment Standard Transfer Specification: An IEC standard
Don Taylor, STS Association, South Africa
The Standard Transfer Specification is a secure message protocol between a POS and
a Meter, supported by a secure Key Management System and protocol. The STS has
been an industry standard since 1994 and is now also published as IEC/PAS 62055­
41. It is currently being converted into a full IEC standard and publication is targeted
for 1st
half of 2006. There are approximately 5 million STS meters installed in about 30
countries and operated by about 300 utility companies. This entire user base is served
from one Key Management Center with about 700 Supply Group keys under its
management care.
The STS Association is the custodian of the STS and continues to sustain the standard
in all its phases from development to application and maintenance. It also assures the
integrity and quality of the support infrastructure and facilitates access to services like
key management, product certification and the further development of standards.
Members currently comprise of 18 manufacturers, 2 utility companies and one
AMEU/ESLC representative.
Activities of the STS Association are focusing on facilitation of key management
services, product certification services, certification of other key management systems
and codes of practice for key management centers. It is actively participating on WG15
of IEC TC13 towards creation of the full IEC standard, developing enhancements to the
STS and to the existing key management system.
IEC standards that are relevant to prepayment meters, which are already published or
in final stage of publication are IEC 62051 (Glossary of terms), IEC 62052­11: General
requirements for metrology, IEC 62053­21: Particular requirements for metrology, IEC
62055­21: Framework for standardization, IEC 62055­31: Particular requirements for
payment meters and IEC 62055­41: Standard Transfer Specification.
The IEC 62055­21 Framework looks at the standardization of payment metering
systems and covers processes, functions, data elements, system entities and
interfaces from a generic perspective. It further advocates a scheme whereby many
systems or subsystems may be standardized within the IEC 62055 set of standards,
such as the STS, which is thus the first one in the set to be standardized in this
fashion. Generic functions and processes with sub­classification of functions for a
single part payment meter are also detailed.
The IEC 62055­41 Standard Transfer Specification uses the OSI reference model
defining at least an application layer and physical layer protocol with the token carrier
as the medium in the physical layer. This makes the standard more versatile and
manageable. It also defines the generic structure for a Virtual Meter in terms of
Function Objects, which in turn describe the functionality of the payment meter and,
which are then specifically defined in Companion Standards under the management of
the STS Association.
Enhancements to the STS, currently under development, follow the same IEC
reference model and maintain backward compatibility with the present STS version.
Main features of the enhancements are: bulk data transfer token; token frame with up
to 255 tokens in one frame; feedback data from the meter via the token carrier; 2 way

3. token carrier; 21 digit numeric token; The Companion Standards currently under
consideration are: step tariff with auxiliary charges; accounting function with social
credit, token credit, credit advance and lifeline credit; metering for water; control valve
for water; real­time clock with battery;
Requirements for key management enhancements under consideration are: the key
management center should be globally trusted, industry impartial and cater for the
deregulated market; services should be automated on 24/7 basis and remotely
accessible; variety of secure module formats, remote coding and inter ­ KMC key
exchange protocol.
In conclusion it would be true to say that prepayment is still growing and developing
and establishing support infrastructure in the international arena, while maintaining
healthy standards.

4. Don Taylor
chairperson
STS Association ­ South Africa
Standard Transfer Specification:
Standard Transfer Specification:
an
an
IEC Standard
IEC Standard
www.
www.sts
sts.org.
.org.za
za
• Payment
• Credit
• Encryption
• Token
• Decryption
• Credit
• Consumption
• Key
Management
STS ?
STS ? Point Of Sale
Prepayment Meter
Credit
Token
Credit
Encrypt
Decrypt
Key
Key
Payment
Consumer
Supply M
Consumption
Key
Management
System

5. • Secure message protocol ­ POS / Meter
• Secure key management system + protocol
• IEC standard
• 5 million meters
• 30 countries
• 300 utilities
• 1 Key Management Center ­ South Africa
• 700 SGC keys
STS ?
STS ? Standard Transfer Specification
Standard Transfer Specification
• Custodian of the STS
• Facilitates the support infrastructure
• Key Management, Certification and Standards
• 21 members
• 19 manufacturers + 2 utilities + AMEU/ESLC
STS Association ?
STS Association ?

6. • Key management services
• Certification of products
• Certification of key management systems
• Codes of practice for key management
• IEC standardization
• STS enhancement
• Key management enhancement
STSA focus ?
STSA focus ?
• 62051 : Glossary
• 62052­11: General requirements (metrology)
• 62053­21: Particular requirements (metrology)
• 62055­21: Framework for standardization
• 62055­31: Type Specification (payment meter)
• 62055­41: Standard Transfer Specification
IEC
IEC ­
­ Payment Meters
Payment Meters

7. • General
system
concepts
IEC
IEC ­
­ Concept model
Concept model (62055
(62055­
­21)
21)
Processes
use
Data Elements Functions
System Entities
Users Devices
use
embodied in embodied in
comprises comprises
instance instance
operate
on
instances
Supplier
Customer
Operator
Installer
Inspector
Token
Carrier
Payment
Meter
Interfaces
Interfaces
• More than
one
standard
• Create
when
required
• STS is 1st
one of
the set
IEC
IEC ­
­ Framework
Framework (62055
(62055­
­21)
21)
Payment Meters
Token Carriers
Customer Information Systems
Data Elements
Generic functions
Generic processes
Point Of Sale Systems
System
1
System
2
System
n
use
CIS to POS Interfaces
use
use
Token Carrier to Meter Interfaces
POS to Token Carrier Interfaces

8. • Single­
part
payment
meter
• Generic
functions
IEC
IEC ­
­ Meter model
Meter model (62055
(62055­
­21)
21)
Token Token
Carrier
Token Carrier
Interface
Accounting
Metering
Delivery
Supply
network
Load circuit
metered supply
delivered supply
connected supply
Display
Recording
Test
Security
Time
Meter
Application
Process
User
Interface
(62055­41)
• STS tokens
• STA
• DES
• Mag card
• Numeric
• Serial port
IEC
IEC –
– Standard Transfer Specification
Standard Transfer Specification
Physical Layer
Protocol
Application Layer
Protocol
TCDU
POS
Application
Process
APDU
Physical Layer
Protocol
Application Layer
Protocol
TCDU
METER
Application
Process
APDU
Key Management Virtual Meter
Function Objects
Token Carrier
Standard Transfer
Specification
Companion
Standards

9. • Follows IEC model
• Backward compatible
• Bulk token (40­940 bits)
• Token frame (255 tokens)
• Feedback from meter
• 2 way token carrier (Dallas iButton, Smart card)
• Companion standards
STS
STS ­
­ Enhancement
Enhancement
• Step tariff
• Auxiliary charge
• Social credit
• Token credit
• Credit advance
• Lifeline credit
• Metering (water meter)
• Delivery (water valve)
• Real­time clock
• Battery backup
Companion Standards
Companion Standards

10. • Requirements
• Globally trusted Key Management Center
• Industry impartial Key Management Center
• Deregulated market needs
• Distributed services architecture
• Automated services 24/7
• Remote Secure Module coding
• Variety of Secure Module formats
• Inter – KMC protocol
• Standards repository
Key Management
Key Management enhancement
enhancement
• International arena
• Creating support infrastructure
• Providing services
STSA
STSA ­
­ STS
STS ­
­ IEC
IEC

11. • Article in Metering International
• Visit our website : www.
www.sts
sts.org.
.org.za
za
• Join the STS Association
• Come speak to me
Finally ?
Finally ?

12. Biography
Speaker: Don Taylor
Position: Chairman
Company: STS Association
Country: South Africa
Don Taylor is the Director of Technology for Actaris Measurement & Systems (Pty) Ltd. He is
currently Chairman of the STS Association and a participating working group member on
various standards organisations such as the SANC for the IEC, SANS, NRS, STS Association
and IEC. He is also a longstanding member of the SAIMC.
In 1976 he graduated with a Higher National Diploma in Electrical Engineering from the Cape
College for Advanced Technical Education, after which he worked for 2 years in the gold
mining industry followed by 10 years for the CSIR and 18 years in the prepayment industry.
He is recognized as a co­founder of the prepayment industry in SA and developer of the first
commercialized solid­state integrated prepayment meter worldwide in 1985. He also co­
founded the first South African prepayment meter manufacturing company Angcon
Technologies in 1986, which later became AEG Energy Control, then Schlumberger and now
Actaris. In 1994 he co­founded the IEC WG15 for payment systems and in 1997 co­founded
the STS Association of which he has been chairman since 2000.

13. Company Background Information
Company: STS Association
Country: South Africa
The STS Association ensures that users of the Standard Transfer Specification have the
supporting infrastructure to enable the secure operation of prepayment systems, and assures
the interoperability of equipment from different suppliers through the certification of STS
compliant equipment. The Association promotes the application of the standard, and further
develops it to meet emerging international needs for additional functionality.