Which is the best and most secure messenger program?

There are several in field about secure messenger.

Signal VS Telegram VS WhatsApp VS Wickr

Signal Explained

The Signal Technology Protocol is used by several apps such as Signal own app, Facebook Messenger, WhatsApp and Google Allo.

The signal protocol explained as a cryptographic protocol that allows end to end encryption for instant messaging services.

It is easy to use and major players like WhatsApp started to use it to encrypt all their messages.

The protocol of Signal is build by Open Whisper System that is a non profit group founded in 2013 by the header of security at Twitter Moxie Marlinspike.

Open Whisper System is heading the development of the Signal Protocol and maintaining the Signal App for several platforms.

Due to the non profit structure it is paid for by grants and donations.

The Signal protocol was audited in October 2016 by international team of security experts and got high rating reviews.

So this can lead people to believe that since Facebook Messenger, Google Allo and WhatsApp uses the Signal Protocol they are secure.

This might be misleading because Google Allo, Facebook Messenger do not enable end to end encryption by default. Users have to enable Secret Conversations on Facebook Messenger and on Google Allo must enable Incognito mode which neither is enabled by default.

The Signal protocol has been praised by former whistle blower Edward Snowden. The apps code is open source by Open Whisper Systems and can be examined by anyone at GitHub.

Signal also has user identification to make sure you are talking to the right person. It also supports free encrypted calls world wide and to create encrypted groups and send files encrypted.

The only data Signal obtains i the phone number when a user register and login to the server.

Signal might be the most secure and most strong example compared to Telegram which uses their own encryption that has not been peer reviewed.

Also Signal is free no advertisers or cost to use it.

The big weakness of Signal is it needs your phone number on sign up.

Telegram Explained

Telegram is made by the social networks VKs founder Pavel Durov. It uses its own private MTProto protocol for encryption.

It has been subject to controversies about its encryption protocol. In 2015 a security expert published a technical paper detailing a theoretical weaknesses in MTProto. Telegram debunked it in a blog post.

Telegram was launched in the same year as Snowden leaks to offer great and easy to use encryption.

Telegram Protocol is claimed that all data send with the protocol through them cannot be intercepted from any provider.

Telegram offer a self destruct feature for messages or a secret chat option for extra privacy. It is said that Telegram accesses and stores your contact list on its server.

Then they can sent you notifications when one from your contact list joins Telegram. Data such as videos, photos, messages are also encrypted and store on their server.

The weakness might be if someone has a master key and can access all the data. 

WhatsApp Explained

Signal and WhatsApp uses the Signal Protocol enabled by default on all messages sent.

Then why can WhatsApp not be the ultimate security messenger?

The problem is WhatsApp collect meta data.

Meta data data collection have been discussed as a security risk.

WhatsApp might argue that with meta data they cant listen or read your communications due to the end to end encryption and they only collect useless meta data.

In the WhatsApp FAQ it states that it do have access to all phone numbers in your address book and it collect myriad of information about you.
WhatsApp do not store your messages on their servers but it is stored locally on your phone.

But if you backup your phone as example on iPhone with iCloud then the messages can get to the cloud servers.

Another problem is what they collect about who you communicate with.
In their own FAQ it says they collect service related diagnostic with performance info.

It includes activity how it is used with the services. It collects log files diagnostic crash and other reports.
Further more it collect device information such as model of phone OS version IP address, your phone number and more.
So for privacy concerns WhatsApp is not a good privacy choise.

And of course Facebook acquired WhatsApp that creates new privacy concerns.

Wickr Explained

Wickr says it uses military grade encryption. It has support of more than 22 languages.

They say they can not read any messages sent or images.

Wickr has a great bounty program for hackers that make up to $100,000 if they find a vulnerability.

Wickr might be the winner since it has easily expiring messages, it has anonymous signup and it don' collect data.