IONU is a new messaging tool for Windows, Mac OS, Android and iPhone, the program can be used by individuals or an organization that needs central administration capabilities.
During the Windows installation you will be given a warning that the digital signature is not valid and the publisher can not be verified, the installer will also automatically download Microsoft Visual C++ runtime libraries if they are not present in your system.
Account creation was relatively easy, just pick a username and a passphrase. IONU will force you to utilize a minimum of 8 characters password that combines letters and numbers. You will have to add three security questions for password recovery and a link is sent to your email where you have to click to confirm that you own that inbox. If you use IONU in multiple devices, like mobile and desktop, data will be synced across them without you doing anything, a central IONU server manages the data and updates your client when you first login.
In order for people to be able to find you in the messenger, you will have to set up an account identifier with your email address, name and phone number, if somebody wishes to connect with you they only need to search for this information and send you a friend request. It is not necessary to make visible your phone number an email, you can just use a nickname, privacy options can be managed in the client settings.
You can only communicate with people added to your contacts list, this stops spam. Chat messages and file transfers are encrypted, IONU says that they have no way to read the chat even if they wanted to and you get delivery and read reports, with an optional “Vanish” function that sets an expiry date to your messages, after which they will no longer be readable. The program can also be used to encrypt data to the cloud, it supports Dropbox and Box.
I could not find any detailed explanation about IONU security specs and a central server forwarding the messages is always a concern in case it is ever compromised, adding that IONU is an American company and the history that USA companies have of being subject to NSA spy gagging orders. The company says it is not viable for them to decrypt anything for anybody but I was not totally convinced that a government can not force them to mess with their server to download malware or something else to a target customer .
Assuming you trust IONU claims that they aren’t able to read anything and you trust the encryption scheme they are using is safe, it seems like a good app to have private conversations out of the reach of malicious hackers sniffing packets on your network and a good way to protect your privacy by sending lapsing messages that can not be saved, although metadata should still be available in IONU servers, like login connection times and computer IPs.
If your main concern is protection from criminals, IONU is a far better option than WhatsApp or Yahoo Messenger, if you are up against the NSA, I would look for another solution like the Torsion messenger for anonymous chat over Tor, or a program that has no central server managing messages.