IEC 62055-41:2018

IEC 62055-41 ®
Edition 3.0 2018-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electricity metering – Payment systems –
Part 41: Standard transfer specification (STS) – Application layer protocol for
one-way token carrier systems
Comptage de l'électricité – Systèmes de paiement –
Partie 41: Spécification de transfert normalisé (STS) – Protocole de couche
application pour les systèmes de supports de jeton unidirectionnel

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IEC 62055-41 ®
Edition 3.0 2018-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electricity metering – Payment systems –

Part 41: Standard transfer specification (STS) – Application layer protocol for

one-way token carrier systems
Comptage de l'électricité – Systèmes de paiement –

Partie 41: Spécification de transfert normalisé (STS) – Protocole de couche

application pour les systèmes de supports de jeton unidirectionnel

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 35.100.70; 91.140.50 ISBN 978-2-8322-5499-8

– 2 – IEC 62055-41:2018 © IEC 2018
CONTENTS
FOREWORD . 9
INTRODUCTION . 11
1 Scope . 14
2 Normative references . 14
3 Terms, definitions, abbreviated terms, notation and terminology . 15
3.1 Terms and definitions . 15
3.2 Abbreviated terms . 17
3.3 Notation and terminology . 19
4 Numbering conventions . 19
5 Reference model for the standard transfer specification . 20
5.1 Generic payment meter functional reference diagram . 20
5.2 STS protocol reference model . 21
5.3 Dataflow from the POSApplicationProcess to the TokenCarrier . 22
5.4 Dataflow from the TokenCarrier to the MeterApplicationProcess . 22
5.5 MeterFunctionObjects / companion specifications . 24
5.6 Transaction reference numbers . 24
6 POSToTokenCarrierInterface application layer protocol . 24
6.1 APDU: ApplicationProtocolDataUnit . 24
6.1.1 Data elements in the APDU . 24
6.1.2 MeterPAN: MeterPrimaryAccountNumber . 26
6.1.3 TCT: TokenCarrierType . 27
6.1.4 DKGA: DecoderKeyGenerationAlgorithm . 28
6.1.5 EA: EncryptionAlgorithm . 28
6.1.6 SGC: SupplyGroupCode . 28
6.1.7 TI: TariffIndex . 29
6.1.8 KRN: KeyRevisionNumber . 29
6.1.9 KT: KeyType . 29
6.1.10 KEN: KeyExpiryNumber . 30
6.1.11 DOE: DateOfExpiry . 30
6.1.12 BDT: BaseDate . 30
6.2 Tokens . 31
6.2.1 Token definition format . 31
6.2.2 Class 0: TransferCredit . 31
6.2.3 Class 1: InitiateMeterTest/Display. 32
6.2.4 Class 2: SetMaximumPowerLimit . 32
6.2.5 Class 2: ClearCredit . 32
6.2.6 Class 2: SetTariffRate . 32
6.2.7 Key change token set for 64-bit DecoderKey transfer . 33
6.2.8 Key change token set for 128-bit DecoderKey transfer . 34
6.2.9 Class 2: ClearTamperCondition . 35
6.2.10 Class 2: SetMaximumPhasePowerUnbalanceLimit . 35
6.2.11 Class 2: SetWaterMeterFactor . 35
6.2.12 Class 2: Reserved for STS use . 35
6.2.13 Class 2: Reserved for Proprietary use . 36
6.2.14 Class 3: Reserved for STS use . 36
6.3 Token data elements. 36

6.3.1 Data elements used in tokens . 36
6.3.2 Class: TokenClass . 37
6.3.3 SubClass: TokenSubClass . 38
6.3.4 RND: RandomNumber . 38
6.3.5 TID: TokenIdentifier . 39
6.3.6 Amount: TransferAmount . 40
6.3.7 CRC: CyclicRedundancyCheck . 44
6.3.8 Control: InitiateMeterTest/DisplayControlField . 45
6.3.9 MPL: MaximumPowerLimit . 46
6.3.10 MPPUL: MaximumPhasePowerUnbalanceLimit . 46
6.3.11 Rate: TariffRate . 46
6.3.12 WMFactor: WaterMeterFactor . 46
6.3.13 Register: RegisterToClear . 46
6.3.14 NKHO: NewKeyHighOrder . 46
6.3.15 NKLO: NewKeyLowOrder . 46
6.3.16 NKMO1: NewKeyMiddleOrder1 . 46
6.3.17 NKMO2: NewKeyMiddleOrder2 . 47
6.3.18 KENHO: KeyExpiryNumberHighOrder . 47
6.3.19 KENLO: KeyExpiryNumberLowOrder . 47
6.3.20 RO: RolloverKeyChange . 47
6.3.21 S&E: SignAndExponent . 47
6.3.22 CRC_C: CyclicRedundancyCheck_C . 47
6.4 TCDUGeneration functions . 47
6.4.1 Definition of the TCDU . 47
6.4.2 Transposition of the Class bits . 48
6.4.3 TCDUGeneration function for Class 0,1 and 2 tokens . 48
6.4.4 TCDUGeneration function for key change tokens . 50
6.4.5 TCDUGeneration function for Set2ndSectionDecoderKey token . 51
6.5 Security functions . 51
6.5.1 General requirements . 51
6.5.2 Key attributes and key changes . 51
6.5.3 DecoderKey generation . 59
6.5.4 STA: EncryptionAlgorithm07 . 66
6.5.5 DEA: EncryptionAlgorithm09 . 69
6.5.6 MISTY1: EncryptionAlgorithm11 . 69
7 TokenCarriertoMeterInterface application layer protocol . 71
7.1 APDU: ApplicationProtocolDataUnit . 71
7.1.1 Data elements in the APDU . 71
7.1.2 Token . 72
7.1.3 AuthenticationResult . 72
7.1.4 ValidationResult . 72
7.1.5 TokenResult . 73
7.2 APDUExtraction functions . 74
7.2.1 Extraction process . 74
7.2.2 Extraction of the 2 Class bits . 74
7.2.3 APDUExtraction function for Class 0 and Class 2 tokens . 75
7.2.4 APDUExtraction function for Class 1 tokens . 76
7.2.5 APDUExtraction function for key change token set . 76
7.3 Security functions . 77

– 4 – IEC 62055-41:2018 © IEC 2018
7.3.1 Key attributes and key changes . 77
7.3.2 DKR: DecoderKeyRegister . 77
7.3.3 STA: DecryptionAlgorithm07 . 78
7.3.4 DEA: DecryptionAlgorithm09. 81
7.3.5 MISTY1: DecryptionAlgorithm11 . 81
7.3.6 TokenAuthentication . 83
7.3.7 TokenValidation . 83
7.3.8 TokenCancellation . 84
8 MeterApplicationProcess requirements . 84
8.1 General requirements . 84
8.2 Token acceptance/rejection . 85
8.3 Display indicators and markings . 86
8.4 TransferCredit tokens . 86
8.5 InitiateMeterTest/Display tokens . 86
8.6 SetMaximumPowerLimit tokens . 87
8.7 ClearCredit tokens . 87
8.8 SetTariffRate tokens . 87
8.9 Key change tokens . 87
8.10 Set2ndSectionDecoderKey tokens . 88
8.11 ClearTamperCondition tokens . 88
8.12 SetMaximumPhasePowerUnbalanceLimit tokens . 88
8.13 SetWaterMeterFactor . 88
8.14 Class 2: Reserved for STS use tokens . 88
8.15 Class 2: Reserved for Proprietary use tokens . 88
8.16 Class 3: Reserved for STS use tokens . 89
9 KMS: KeyManagementSystem generic requirements . 89
10 Maintenance of STS entities and related services . 89
10.1 General . 89
10.2 Operations . 91
10.2.1 Product certification maintenance . 91
10.2.2 DSN maintenance . 91
10.2.3 RO maintenance . 91
10.2.4 TI maintenance . 91
10.2.5 TID maintenance . 92
10.2.6 SpecialReservedTokenIdentifier maintenance . 92
10.2.7 MfrCode maintenance . 92
10.2.8 Substitution tables maintenance . 92
10.2.9 Permutation tables maintenance . 92
10.2.10 SGC maintenance. 92
10.2.11 VendingKey maintenance . 92
10.2.12 KRN maintenance . 92
10.2.13 KT maintenance . 92
10.2.14 KEN maintenance . 93
10.2.15 CERT maintenance . 93
10.2.16 CC maintenance . 93
10.2.17 UC maintenance . 93
10.2.18 KMCID maintenance . 93
10.2.19 CMID maintenance . 93
10.3 Standardisation . 93

10.3.1 IIN maintenance . 93
10.3.2 TCT maintenance . 94
10.3.3 DKGA maintenance . 94
10.3.4 EA maintenance . 94
10.3.5 TokenClass maintenance . 94
10.3.6 TokenSubClass maintenance . 94
10.3.7 InitiateMeterTest/DisplayControlField maintenance . 94
10.3.8 RegisterToClear maintenance . 95
10.3.9 STS BaseDate maintenance . 95
10.3.10 Rate maintenance . 95
10.3.11 WMFactor maintenance . 95
10.3.12 MFO maintenance . 95
10.3.13 FOIN maintenance . 96
10.3.14 Companion specification maintenance . 96
Annex A (informative) Guidelines for a KeyManagementSystem (KMS) . 97
Annex B (informative) Entities and identifiers in an STS-compliant system . 101
Annex C (informative) Code of practice for the implementation of STS-compliant
systems . 105
C.1 General . 105
C.2 Maintenance and support services provided by the STS Association . 105
C.3 Key management . 105
C.3.1 Key management services . 105
C.3.2 SupplyGroupCode and VendingKey distribution . 105
C.3.3 CryptographicModule distribution . 106
C.3.4 Key expiry . 107
C.4 MeterPAN . 107
C.4.1 General practice . 107
C.4.2 IssuerIdentificationNumbers . 107
C.4.3 ManufacturerCodes . 107
C.4.4 DecoderSerialNumbers . 108
C.5 SpecialReservedTokenIdentifier . 108
C.6 Permutation and substitution tables for the STA . 108
C.7 EA codes . 108
C.8 TokenCarrierType codes . 108
C.9 MeterFunctionObject instances / companion specifications . 109
C.10 TariffIndex . 109
C.11 STS-compliance certification . 109
C.11.1 IEC certification services . 109
C.11.2 Products . 109
C.11.3 Certification authority . 109
C.12 Procurement options for users of STS-compliant systems . 109
C.13 Management of TID roll over . 113
C.13.1 Introduction . 113
C.13.2 Overview . 114
C.13.3 Impact analysis . 115
C.13.4 Base dates . 116
C.13.5 Implementation . 116
Bibliography . 119

– 6 – IEC 62055-41:2018 © IEC 2018
Figure 1 – Functional block diagram of a generic single-device payment meter . 20
Figure 2 – STS modelled as a 2-layer collapsed OSI protocol stack . 21
Figure 3 – Dataflow from the POSApplicationProcess to the TokenCarrier . 22
Figure 4 – Dataflow from the TokenCarrier to the MeterApplicationProcess . 23
Figure 5 – Composition of transaction reference number . 24
Figure 6 – Transposition of the 2 Class bits . 48
Figure 7 – TCDUGeneration function for Class 0, 1 and 2 tokens . 49
Figure 8 – TCDUGeneration function for key change tokens . 50
Figure 9 – DecoderKey changes – state diagram . 57
Figure 10 – DecoderKeyGenerationAlgorithm01 . 62
Figure 11 – DecoderKeyGenerationAlgorithm02 . 63
Figure 12 – STA: EncryptionAlgorithm07 . 66
Figure 13 – STA encryption substitution process . 67
Figure 14 – STA encryption permutation process . 68
Figure 15 – STA encryption DecoderKey rotation process . 68
Figure 16 – STA encryption worked example for TransferCredit token . 69
Figure 17 – MISTY1: EncryptionAlgorithm11 . 70
Figure 18 – MISTY1 encryption worked example for TransferCredit token . 71
Figure 19 – APDUExtraction function . 74
Figure 20 – Extraction of the 2 Class bits . 75
Figure 21 – STA DecryptionAlgorithm07 . 78
Figure 22 – STA decryption permutation process . 78
Figure 23 – STA decryption substitution process . 79
Figure 24 – STA decryption DecoderKey rotation process . 80
Figure 25 – STA decryption worked example for TransferCredit token . 81
Figure 26 – STA DecryptionAlgorithm11 . 82
Figure 27 – MISTY1 decryption worked example for TransferCredit token . 82
Figure A.1 – KeyManagementSystem and interactive relationships between entities . 97
Figure B.1 – Entities and identifiers deployed in an STS-compliant system . 101
Figure C.1 – System overview . 114

Table 1 – Data elements in the APDU . 25
Table 2 – Data elements in the IDRecord . 25
Table 3 – Data elements in the MeterPAN. 26
Table 4 – Data elements in the IAIN / DRN . 26
Table 5 – Token carrier types . 27
Table 6 – DKGA codes . 28
Table 7 – EA codes . 28
Table 8 – SGC types and key types . 29
Table 9 – DOE codes for the year . 30
Table 10 – DOE codes for the month . 30
Table 11 – BDT representation . 31
Table 12 – Token definition format . 31

Table 13 – Data elements used in tokens . 36
Table 14 – Token classes . 37
Table 15 – Token sub-classes . 38
Table 16 – TID calculation examples . 39
Table 17 – Units of measure for electricity . 40
Table 18 – Units of measure for other applications. 41
Table 19 – Bit allocations for the Amount field for SubClass 0 to 3 . 41
Table 20 – Maximum error due to rounding . 42
Table 21 – Examples of TransferAmount values for credit transfer . 42
Table 22 – Bit allocations for the Amount field for SubClass 4 to 7 . 42
Table 23 – Bit allocations for the exponent e . 42
Table 24 – Examples of rounding of negative and positive values . 43
Table 25 – Examples of TransferAmounts and rounding errors . 44
Table 26 – Example of a CRC calculation . 44
Table 27 – Permissible control field values . 45
Table 28 – Selection of register to clear . 46
Table 29 – S&E bit positions for variables s, e , e and e . 47
4 3 2
Table 30 – Example of a CRC_C calculation . 47
Table 31 – Classification of vending keys . 53
Table 32 – Classification of decoder keys . 53
Table 33 – Permitted relationships between decoder key types . 58
Table 34 – Definition of the PANBlock . 60
Table 35 – Data elements in the PANBlock . 60
Table 36 – Definition of the CONTROLBlock . 60
Table 37 – Data elements in the CONTROLBlock . 60
Table 38 – Range of applicable decoder reference numbers . 61
Table 39 – List of applicable supply group codes . 62
Table 40 – Data elements in DataBlock. 64
Table 41 – Input parameters for a worked example . 65
Table 42 – DataBlock example construction . 65
Table 43 – DecoderKey construction example . 65
Table 44 – Sample substitution tables . 67
Table 45 – Sample permutation table . 68
Table 46 – Data elements in the APDU . 72
Table 47 – Possible values for the AuthenticationResult . 72
Table 48 – Possible values for the ValidationResult . 73
Table 49 – Possible values for the TokenResult . 73
Table 50 – Values stored in the DKR . 77
Table 51 – Sample permutation table . 79
Table 52 – Sample substitution tables . 80
Table 53 – Entities/services requiring maintenance service. 90
Table A.1 – Entities that participate in KMS processes . 98
Table A.2 – Processes surrounding the payment meter and DecoderKey . 98

– 8 – IEC 62055-41:2018 © IEC 2018
Table A.3 – Processes surrounding the CryptographicModule . 99
Table A.4 – Processes surrounding the SGC and VendingKey . 99
Table B.1 – Typical entities deployed in an STS-compliant system . 102
Table B.2 – Identifiers associated with the entities in an STS-compliant system. 103
Table C.1 – Data elements associated with a SGC . 106
Table C.2 – Data elements associated with the CryptographicModule . 107
Table C.3 – Items that should be noted in purchase orders and tenders . 110

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICITY METERING – PAYMENT SYSTEMS –

Part 41: Standard transfer specification (STS) –
Application layer protocol for one-way token carrier systems

FOREWORD
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International Standard IEC 62055-41 has been prepared by IEC technical committee 13:
Electrical energy measurement and control.
This third edition cancels and replaces the second edition of IEC 62055-41, issued in 2014. It
constitutes a technical revision.
The main technical changes with regard to the previous edition are as follows:
• currency transfer tokens for electricity, water, gas and time metering;
• finer resolution for gas and time credit transfer;
• common code PAN for 2 and 4 digit manufacturer codes;
• reserved MfrCode values for certification and testing purposes;
• provision for DLMS/COSEM as a virtual token carrier type;

– 10 – IEC 62055-41:2018 © IEC 2018
• addition of DKGA04, an advanced key derivation function from 160-bit VendingKey;
• withdrawal of DES for EA09 and TDES for DKGA03 cryptographic algorithms, but DES for
DKGA02 remains in use;
•
...