WhatsApp Messenger is a proprietary, cross-platform
instant messaging application for smartphones.
In addition to text messaging, users can send each other images, video, and
audio media messages. The client software is available for: Android; BlackBerry OS,
BlackBerry 10,
iOS; Series 40,
Symbian (S60);
and, Windows Phone.
The company by the same name was founded in 2009 by Brian Acton and Jan
Koum, both veterans of Yahoo! and is based in Santa Clara, California.
Competing
with a number of Asia-based messaging services (like LINE and KakaoTalk),
WhatsApp handles ten billion messages per day as of August 2012, growing from
two billion in April 2012and one billion the previous October. According to the
Financial
Times, WhatsApp "has done to SMSSkype did to international
calling on landlines." on mobile phones what Skype did to international
calling on landlines."Technical specifics
WhatsApp uses a customized version of the open standard Extensible Messaging and Presence Protocol (XMPP). Upon installation, it creates a user account using one's phone number as username (Jabber ID:
[phone
number]@s.whatsapp.net). WhatsApp software automatically compares all
phone numbers from the device's address book with its central database of WhatsApp
users to automatically add contacts to the users WhatsApp contact list.
Previously the Android and s40 versions used an MD5-hashed,
reversed-version of the phone's IMEI as password, the iOS
version used the phone's WiFi MAC address instead of IMEI. A recent update
now generates a random password on the server side.Multimedia messages are sent by uploading the image, audio or video to be sent to a HTTP server and then sending a link to the content along with its Base64 encoded thumbnail (if applicable).
Until August 2012, messages were sent in unencrypted plain-text format, making the system vulnerable to session hijacking. As of 15 August 2012, the WhatsApp Support Staff claims messages are encrypted in the "latest version" of the WhatsApp software for iOS and Android (not including BlackBerry, Windows Phone and Symbian), without specifying the implemented cryptographic method.
