PayEx IFSF H2H Security specification

Version 2.2 by Pål-Eirik Askerød on 2017/10/30 08:20

Key schemes

Currently PayEx only support H2H Shared keys for MAC, PIN and Data Encryption.

This solution defines three different keys which are shared with the 3rd party that integrates the PayEx H2H IFSF protocol.

3rd partys will be assigned a uniq key version that needs to be specified in requests towards PayEx Host. 

Security Related Control Information

This information is transported in P-53 towards PayEx Host. For scheme H2H Shared keys only 53-6 needs to be populated with the version of keys.

This field (53-6) needs to be present in all request that have MAC, PIN or encrypted data. (P-127)

ElementNameFormatAttributeDescription
53 n2LLVAR length field
53-1Master key generation numbern1Identifies the master key generation. Currently NOT supported
53-2Key version of master keyn1Identifies the key version. Currently NOT supported
53-3MAC random valueb16ZKA MAC random value. Currently NOT supported
53-4PAC random valueb16

ZKA PAC random value. Zero filled if no PIN block in the message. Currently NOT supported

53-5Data encryption random valueb16ZKA Data encryption random value. Currently NOT supported
53-6H2H Key versionn2Version of keys shared by PayEx with 3rd party. Eks "02"

PIN Encryption Methodology

This information is transported in P-48.14 field towards PayEx Host. 

ElementNameFormatAttributeDescription
48 n3LLLVAR length field
48-14PIN Encryption Methodologyans2Identifies the key version used for pin block encryption. Supported values listed below.

 ‘13’: PayEx H2H shared keys

 ‘33’: ZKA MS/SK PAC H2H (Currently not supported)

When P-52 is present in request, this field must also be present. When field P-52 is NOT present, field 48-14 should also NOT be present.

The value currently supported by PayEx is ‘13’ and refers to PayEx H2H shared keys. Other values are currently not supported.

PayEx H2H shared key scheme defines a pin encryption key that is used to encrypt the pin block. See PIN section for details.

Message Authentication Code (MAC)

We use ANS X9.9 Option 1 (binary data) procedure using ISO 16609 CBC-mode Triple-DES (TDES) encryption of the data.

Uses a double-length key.

Mac calculation method:

1509348013142-123.png

PIN

Data encryption

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Created by Pål-Eirik Askerød on 2017/10/26 09:58