66AK2G12: Can the T1 K2G General-purpose EVM Kit accomplish the process of secure end-to-end communication? Thank you very much!

The TI design that you referred is a audio equalizer example that takes data from audio Line in and processes the data and sends the data out from Line out. The design does use AIC3106 for converting audio to digital input to MCASP on K2G . The same concept can also be used for speech.

Since the example doesn`t use microphones for input so the better design for you to refer would be the audio pre-processing demo that uses a circular microphones array board for input
www.ti.com/.../TIDEP-0088
processors.wiki.ti.com/.../Processor_SDK_RTOS_Audio_Pre-Processing

This shows how speech input can be captured and how beam forming can be used to perform for speech recognition. This design uses PCM1864 to convert speech signal to digital audio input. For Encryption the device contains HW crypto accelerators for AES and ECDSA which you can leverage using SA LLD driver for encryption.
software-dl.ti.com/.../index_device_drv.html

The device with 1GHz ARM and DSP definitely has the processing power and the HW modules needed for the implementation.

Regards,
Rahul