In January this year, Skype announced the use of signaling protocols with open-to-end encrypted conversations through Open Whispered Systems. This feature has been introduced for Skype IOS, Android, Linux, Mac and Windows Desktop.
To start a secret conversation on this new feature, the 'New Private Conversions' option will be selected from the customer profile or compose menu. After that subscriber will receive an invitation, after receiving it, all calls and messages, and messages in the conversation will be transmitted in encoded condition. Until the conversation ends, call or message will continue in this encrypted method.
In this case, there are some limitations that have been mentioned in the technology site Virg's report. At the same time the user can only take part in a secret conversation from one device. The secret conversation can be taken from one device to another, but the call or message will remain in the device that was sent and received from the device.
Earlier Skype had some kind of encrypted communication facility, but only the sender and the subscriber can see the content of the message in end-to-end coding.