Annex A (normative) UADP Header Layouts

A.2 Message headers for periodic data with fixed layout

A.2.5 Header layout for NetworkMessages with integrity (signing)

UADP messages may be signed to ensure integrity. In this case the SecurityHeader and the Signature have to be added to the message. See clause 7.2.2.4.3 for a complete description of the signing mechanism.
This header layout is basically the same as the header layout defined in A.2.4 but with additional security level ‘signing but no encryption’.
The NetworkMessage header layout with signing is shown in Figure A.2.
Table A.3 shows the configuration for the NetworkMessage header with signing. The table contains only the added or modified rows from Table A.1.
Table A.3 – UADP NetworkMessage header layout with integrity (signing)
Name | Type | Restrictions |
---|---|---|
ExtendedFlags1 | Byte | Bit 4: Security enabled |
SecurityHeader | ||
SecurityFlags | Byte | Bit 0: NetworkMessage Signed enabled Bit 1: NetworkMessage Encryption disabled Bit 2: SecurityFooter disabled Bit 3: Force key reset disabledBit range 4-7: Reserved |
SecurityTokenId | IntegerId | The ID of the security token that identifies the security key in a SecurityGroup. |
NonceLength | Byte | 8 |
MessageNonce | Byte[8] | A number used exactly once for a given security key. |