UADP messages may be signed to ensure integrity. In this case a security header and a signature have to be added to the message. See clause 18.104.22.168.3 for a complete description of the signing mechanism.
This header layout is basically the same as the header layout defined in A.3.4 but with additional security level ‘Signing but no encryption’. The NetworkMessage header layout with signing is shown in Figure A.8.
Table A.9 – UADP NetworkMessage header layout with integrity (signing)
|ExtendedFlags1||Byte||Bit 4: Security enabled|
|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||The length of the Nonce used to initialize the encryption algorithm.|
|MessageNonce||Byte[NonceLength]||A number used exactly once for a given security key.|