Blackberry has always been the go to hardware as far as mobile devices come for the enterprise crowd. A large reason for this has been the strong security features of the BlackBerry smartphone in tandem with encryption which makes the devices really desirable in industries where security is at the helm of priorities.
BBM Protected is a service that BlackBerry has been offering on its Blackberry smartphones so far where the BBMs that you send have the encryption keys which are generated by your smartphone directly. As a result, there is literally no other alternate service in the IM vertical which could be any more secure. However, with BBM now available on Android and iOS for the past couple of years or so, BlackBerry has decided to bring the BBM protected services for Android and iOS. This would work exactly in the same manner as that it does on a normal BlackBerry smartphone, where you can simply initiate a chat between two BBM protected contacts or even invite a contact who is not on BBM Protected for a secure chat.
BlackBerry claims that BBM Protected is the safest way to communicate as far as any corporate communications go and would be really helpful in ensuring there is no man in the middle hacking.