WhatsApp [K 1] is a popular free instant text messaging system for mobile and other platforms with support for voice and video communications. It allows you to send text messages, images, videos, audio and electronic documents over the Internet.
The client runs on the platforms Android, iOS, Windows Phone, Nokia Symbian, Nokia S40, KaiOS, as well as Windows and as a web application.
WhatsApp Inc., which created the messenger, was founded by Jan Coom and Brian Acton on February 24, 2009, and is located in Mountain View, USA ; since October 2014, owned by Facebook Inc.   Since 2016, the application has officially become free and to this day is so  , the user pays only for the Internet traffic used by the application   . The application is used by more than a billion people  .
Due to the high popularity of WhatsApp, the revenue of mobile operators for sending SMS messages between phones is decreasing. According to some 2012 estimates, potential losses could reach tens of billions of dollars  .
- Technical Details
- Selling Facebook
By April 2012, 2 billion messages  , more than 10 billion in August 2012  , more than 27 billion in June 2013   and more than 50 billion messages in March 2015  were sent using WhatsApp . . In February 2018, about 1 billion people sent 55 billion messages per day via WhatsApp  .
According to a statement published in the Financial Times , WhatsApp did the same with SMS as did Skype with international phone calls. As in the case of Skype, the program must be installed on both the sender and the recipient  .
In February 2014, WhatsApp CEO hinted that by summer it was planned to add the functionality of VoIP calls between users  , and at the end of March 2015 this function was implemented on the Android platform. In April 2015, calls appeared on the IOS platform  . In June 2015, the feature became available to owners of WindowsPhone  .
The exact number of users was not disclosed, but, according to estimates of analyst Benedict Evans ( Enders Analysis ), in October 2012 exceeded 100 million. In the Apple app store, the program is the most popular free application in 121 countries (including the largest, except for China, South Korea and Japan)  . According to the Google Play store , at the beginning of November 2012, she crossed the line of 100 million installations on Android devices  . In August 2013, the application totaled 300 million users every month, surpassing WeChat (195 million users), Line and Viber (200 million users each ) in this indicator .KakaoTalk (100 million users) and Skype (280 million users)  . In April 2014, according to the company, the number of active users exceeded 500 million  . As of March 2015, the number of users using WhatsApp from Android devices exceeded 1 billion  . According to data provided by the analytical company App Annie, in 2015, WhatsApp became the most used messenger in the Russian Federation  .
February 19, 2014, Facebook Inc. He announced the acquisition of WhatsApp for 19 billion dollars . Facebook paid $ 4 billion in cash and donated $ 12 billion in equity. In addition, the agreement provides for the transfer of shares with restrictions in the amount of $ 3 billion to the founders and employees of WhatsApp within 4 years after the closing of the transaction  . In the summer of 2016, Facebook announced that it intends to use the phone database compiled by WhatsApp for other services of the corporation, presumably Facebook and Instagram, to improve advertising on Facebook     . Refusal of such use can be given until September 25  .
In early February 2016, the founders of WhatsApp announced in their own blog that the service had reached the 1 billion user bar  .
On March 13, 2019, Facebook experienced the largest glitch in history, lasting about 10 hours. During this time, Facebook, Instagram, Messenger and WhatsApp were not available to many countries around the world. Problems arose due to “server configuration changes”  .
In March 2019, the stage of closed testing of the DarkMode dark mode began, on which the company worked since 2018  .
On July 26, 2019, WhatsApp developers talked about testing a number of updates for the next version 220.127.116.11 on the iOS platform  .
Whatsapp Technical Details
WhatsApp uses a modified Extensible Messaging and Presence Protocol ( XMPP , formerly known as Jabber )  . During installation, an account is created on the s.whatsapp.net server, using the phone number as the username (Jabber ID:)
[номер телефона]@s.whatsapp.net. The Android version automatically uses the MD5 hash from the changed IMEI identifier  as a password , while the iOS version uses the MD5 hash from the MAC address  .
Because of this password generation algorithm and the lack of encryption, WhatsApp has been repeatedly criticized  .
Multimedia messages are sent by uploading an image, sound or video to an HTTP server and transmitting a hyperlink to the object along with a reduced version of the image encoded in Base64  .
WhatsApp automatically syncs your contact list with your phone’s phone book. This is possible due to the fact that all users are registered by their phone number.
.The web version works in conjunction with the telephone and is possible only if the telephone is connected to the Internet.
WhatsApp server software is written in Erlang ; In January 2012, WhatsApp servers used the FreeBSD OS , they had 96 GB of RAM installed, and each one could process from 1 to 2.8 million connections   , which is several orders of magnitude higher than the classic C10k problem . As of the beginning of 2014, the project used about 550 servers, 150 of them serviced the transmission of text messages (1 million users each) 
In 2016, WhatsApp added the ability to invite new members to a group chat using a regular link directly in the message or in the group chat directory  . In 2017, it was simplified to record long voice messages for transmission to the interlocutor  , as well as the function of deleting the message not only at home, but also at the interlocutor (including from chats), available for one hour seven minutes after sending the message [51 ] .
Since the beginning of 2017, the WhatsApp application has ceased support on versions of Android 2.1-2.2, Windows Phone 7 and versions of Apple earlier than iOS 6  . Starting June 30, 2017, support for BlackBerry, Nokia S40, and Nokia Symbian was discontinued  .
In June 2018, WhatsApp introduced the function of creating channels, as in the Telegram messenger  .
In 2018, through the WhatsApp account, the Momo game was widely used  .
On September 10, 2018, the first version of WhatsApp for the KaiOS operating system was released , but only for Indian Reliance Jio mobile phones: JioPhone and JioPhone 2  .
In November 2018, the ability to add your own stickers (through third-party applications) was introduced. This idea was not liked by Apple, offering such application features were removed from the App Store  .
On January 21, 2019, Facebook’s vice president of communications, Victoria Grand, said that in order to avoid rumors and misinformation, there was a restriction on sending one message more than five times; before that, WhatsApp users could share messages with up to 20 users or groups  .
In 2019, WhatsApp plans to start tracking the contacts and interests of its users in order to determine what exactly interests each subscriber, and in accordance with this build an algorithm for displaying statuses. Data on user activity will be stored only on the device, which will minimize the risks of their account.
To combat spam and the possible spread of malware in February 2019, WhatsApp announced a new feature – a ban on adding users to chat rooms without their consent. At the same time, users will choose people from their contact list who can add them to any groups and chats without consent.
In March 2019, it became known that WhatsApp will have a new image search function with which you can check whether the picture is real or fake  .
In April 2019, instant messenger subscribers had the opportunity to manage adding to groups. The user can specify one of the categories: “only contacts”, “all” or “nobody”, and also send invitations to any users valid for 72 hours  . At the same time, testing began on the new WhatsApp feature “Archive Chat Ignore Mode”, which will make it possible to turn off notifications   .
The password generation algorithm and the lack of encryption in earlier versions of WhatsApp have been repeatedly criticized  .
In May 2011, a security hole was reported that left the WhatsApp user account open for session hijacking and packet analysis  . Data transmission in WhatsApp is not encrypted and data is sent and received in clear text – this means that messages can be easily read if the packet path was tracked  . In September 2011, a new version for the iPhone was released, closing a security hole that allowed sending fake messages and reading messages from any WhatsApp user  .
On January 6, 2012, an unknown hacker launched WhatsAppStatus.net, which allowed him to change the status of an arbitrary WhatsApp user if his phone number was known . For this to work, all you had to do was restart the application. According to the hacker, this is just one of the many security issues on WhatsApp. On January 9, WhatsApp reported a solution, although the only measure taken was blocking the IP address of the WhatsAppStatus.net website. In response, a Windows program with the same functionality became available for download. This problem was solved by checking the IP address of the current logged in session   .
In May 2012, security researchers noted that the new version of WhatsApp no longer sends clear-text messages    , but subsequently described the hacking of the encryption method used   . On August 15, 2012, WhatsApp support staff claimed that messages are encrypted in the latest versions for iOS and Android (but not for BlackBerry, Windows Phone, and Symbian), without specifying the encryption method used  .
Until August 2012 messages are sent without encryption, which made possible the attack the session hijacking the [en]  . From August 15, 2012, according to a statement from Techsupport WhatsApp, messages are encrypted in iOS and Android applications, but the encryption method has not been specified  .
|All entries between our user and server are encrypted. We do not store messages after sending. They are stored only on the user’s phone. Honest billionaire! Jan Kum|
On September 14, 2012, The H, a German tech site, demonstrated how to use the WhatsApp API (WhatsAPI) to steal any account  . Soon after, a legal threat was claimed for WhatsAPI developers, characterized by The H as an “obvious reaction” to the security report, and WhatsAPI source code was unavailable for several days. The WhatsApp development team then returned to active development   .
From April 2016 with the release of an update version 2.16.12 WhatsApp included through encryption ( end-to-end ) for all users on the basis of development of the Signal ( the Open the Whisper Systems’ ). Encryption applies to all types of messages: text, photo, video and voice messages. Encryption is also available in group chats. According to the company’s statements, only the recipient can decrypt such messages, the contents are not available even to WhatsApp servers   . The implementation uses ECDH algorithms on Curve25519, AES-256, AES-GCM, HMAC-SHA256, HDKF. Two users can verify encryption keys by scanning a QR code or comparing a 60-digit number, which eliminates class attacksman-in-the-middle  .
In early 2017, it became known that a backdoor was discovered in the message encryption system , allowing Facebookand others secretly change encryption keys and require the sender application to re-encrypt messages on the new keys and resend them (when the “Show Security Notifications” setting is enabled, the sender will see a notification about this fact after the message has been re-encrypted). In fact, this functionality allows Facebook servers to intercept and decrypt user messages. Researcher Tobias Boelter (UCB), who discovered this vulnerability, contacted Facebook in April 2016, but received an answer that the functionality was known to the authors of the system and was “expected behavior”. The company representative explained that the ability to re-encrypt messages is necessary, as some users often change their phones and SIM cards, and the company takes measures,   .
In May 2019, Pavel Durov said that every time WhatsApp needs to eliminate a critical vulnerability in the application, a new one supposedly appears in its place. All identified problems seem to allow surveillance, look and function like backdoors. Durov noted that WhatsApp not only does not publish the source code of the application, as many developers, including Telegram, do, but also “confuses” the service files so that independent researchers can not detect the presence of backdoors. In his opinion, the messenger and its parent company Facebook can allegedly leave these vulnerabilities in the code at the request of US intelligence   .