I am working on solution wherein I have one sidecar alongwith main container in one pod , sidecar is working as a proxy for traffic going out of the pod. Do I need any kind of encryption/TLS security between sidecar and main container if yes then how can I achieve ?
It depends on your security requirements. Traffic between the main container and Istio sidecar is not encrypted. I guess if you are, for example, getting started with Istio or a similar solution and don't know if this is required, it is very likely you don't need that, though.