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 the phone numbers from the device's address book with its central database of WhatsApp users to automatically add contacts to the user's WhatsApp contact list. Previously the Android and S40 versions used an MD5-hashed, reversed-version of the phone's IMEI as password, while the iOS version used the phone's Wi-Fi 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 August 15, 2012, the WhatsApp support staff claim 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.[1
Strengths * Loyal customers * Market share leadership * No need to log * Group Chat * Allow send videos, pictures, voice notes * You can put profile picture * No need to add friends * No need PIN or user number * Avaialable for all platforms * For some platforms is free the first year in order to build customer loyalty. | Weaknesses * Not diversified, becouse other applications offers the same service and also function as social media * Weak distribution network * To access the account can only be paid by