Enable Sign security mode with publisherFixedSize optimisation

Description

Enable the possibility to use sign mode with publisherFixedSize option

Code version identification

SHA : 568d9adc

Current behavior

Currently only none mode is compatible with publisherFixedSize. When sign mode is active whith publisherFixedSize a log message inform you that this combination is not allow and no message are sent.

Expected behavior

Enable the possibility to sign message and use the publisherFixedSize option.

Security impact

Na

Implementation

To enable this option following point shall be taken in consideration :

• The Nonce part of security header should have a fixed sized and a length known at initialisation.

Solution proposed :

• At initialisation the networkMessage Structure shall have his security header set.
• The Nonce position shall be kept
• When updating the PreencodeBuffer calculate the signature add at it at the end of the buffer.
• Once emission done forget the previous signature