The security algorithms used and the length of the KeyNonce for the UADP NetworkMessage depend on the selected SecurityPolicy. The algorithms are defined by SymmetricEncryptionAlgorithm and SymmetricSignatureAlgorithm in OPC 10000-7. The nonce length is part of the SymmetricEncryptionAlgorithm.
The keys used to encrypt and sign messages are extracted from the key data returned from the GetSecurityKeys method (see 8.3.2). This Method returns a sequence of key data with a length that depends on the SecurityPolicyUri, which is also returned by the Method. The layout of the key data is defined in Table 138.
Table 138 – Layout of the key data for UADP message security
|
Name |
Type |
Description |
|
SigningKey |
Byte [SymmetricSignatureAlgorithm Key Length] |
Signing key part of the key data returned from GetSecurityKeys. The SymmetricSignatureAlgorithm is defined in the SecurityPolicy. |
|
EncryptingKey |
Byte [SymmetricEncryptionAlgorithm Key Length] |
Encryption key part of the key data returned from GetSecurityKeys. The SymmetricEncryptionAlgorithm is defined in the SecurityPolicy. |
|
KeyNonce |
Byte [SymmetricEncryption Nonce Length] |
Nonce part of the key data returned from GetSecurityKeys. |