Update the coreSNTP submodule to the latest commit. Also, make updates to the coreSNTP demo for the new changes in the SNTP library which include the following:
1. Update to the type for packet size from size_t to uint16_t for parameters in the transport and authentication interfaces.
2. Change in the call to Sntp_SendTimeRequest API to pass the new blockTimeMs parameter added to the API.
3. Update to the clock-offfset type from int32_t to int64_t for representing information in milliseconds. To accommodate this update in the SntpSetTime_t interface, the mathematical model for representing system clock has been updated to store slew rate as milliseconds/second (instead of second/second). This change improves the accuracy of the WinSim demo time correction (because the milliseconds of time difference between server and client time is corrected over the entire polling interval which makes a significant difference!).
This PR also adds demo config macros for setting the block time values passed to the Sntp_SendTimeRequest and Sntp_ReceiveTimeResponse APIs.
Update the coreSNTP demo to showcase use of symmetric key algorithm of authentication scheme for securing SNTP communication between client and server.
The demo uses the AES-128-CMAC algorithm for the generating Message Authentication Code for the client on sending the SNTP time request to server as well as validating the server response received by verifying if the payload present authentication code can be generated. Use of an authentication mechanism in SNTP communication protects against server spoofing attacks as well as man-in-the-middle attacks of server response modification.
The demo uses corePKCS11 library for the AES-CMAC operations. Also, the demo adds functionality of generating random number, using corePKCS11, for sending as a parameter to the Sntp_SendTimeRequest API.
Note: For symmetric key based security mechanism to be protective against malicious, it is IMPORTANT to securely pre-share the symmetric key between client and server.
Add the FreeRTOS/coreSNTP library as a submodule (along with manifest.yaml file update) and add a demo project to showcase use of the coreSNTP library for having a SNTP client daemon in the system for periodically synchronizing system time with the internet to maintain Coordinated Univeral Time (UTC) in a device. This demo maintains UTC time of system in RAM, thereby, representing systems without a Real-Time Clock (RTC) module in the device.
Note: This demo shows use of coreSNTP library for SNTP communication with NTP/SNTP time servers in non-authenticated mode (i.e. without any security mechanism payload beyond the standard 48 bytes of NTP packet exchange between client-server).
