Audio Encryption in Atmega 328 - p

Can we audio encryption in Arduino Uno? According to this i seem it is possible.

No. Not really. Basically the simplest type of encription is side band inverseion, called scrambling and there is not enough memory and processor speed to do that. Assuming that you mean encryption and not encoding.

so then how can i either encryption or decoding audio ?

What do you want to do with this audio a lot depends on that. A side band inversion can be done by applying an FFT to the audio signal and then reversing the order of the sample bins and applying an inverse FFT transform before sending the audio. To decrepit the audio just apply the same process. However a Uno has not got the processing power to do this in real time.

i want to build real time communication platform such as Radio voice communication.So what is the FFT ?

https://en.wikipedia.org/wiki/Fast_Fourier_transform