ProtonMail

ProtonMail

Screenshot  Screenshot of the ProtonMail website, showing the user's inbox and a composer window.
Type of site	Webmail
Available in	English
Owner	Proton Technologies AG
Created by	Andy Yen Jason Stockman Wei Sun
Website	protonmail.com
Alexa rank	7,967 (December 2016)[1]
Commercial	Yes
Registration	Required
Users	1 million (December 2015 (2015-12))
Launched	16 May 2014 (2014-05-16)
Current status	Active
Content license	MIT License
Written in	PHP and Javascript

ProtonMail is an encrypted-email service founded in 2013 at the CERN research facility by Jason Stockman, Andy Yen and Wei Sun.^[2][3][4] ProtonMail uses client-side encryption to protect email contents and user data before they are sent to ProtonMail servers, in contrast to other common email providers such as Gmail and Hotmail. The service can be accessed through a webmail client or dedicated iOS and Android apps.^[5]

ProtonMail is run by Proton Technologies AG, a company based in the Canton of Geneva, and its servers are located at two locations in Switzerland, outside of US and EU jurisdiction.^[6] The service received initial funding through a crowdfunding campaign. The default account setup is free and the service is sustained by optional paid services. As of December 2015, ProtonMail has approximately 1 million users.^[7] Initially invitation-only, ProtonMail opened up to the public in March 2016.

Features

Upon registration, the user has to provide two passwords: a login password and a mailbox password. The login password is used for authentication, whereas the mailbox password encrypts the user's mailbox, which contains received emails, contacts and user information as well as a private encryption key. Upon logging in, the user has to provide both passwords to access the account as well as the encrypted mailbox and its private encryption key. The decryption takes place client-side, either locally in a web browser or in one of the apps. This system absolves ProtonMail from storing either the unencrypted data or the mailbox password and prevents them from divulging the contents of past emails but not future emails, or from decrypting the mailbox if requested, for instance, if compelled by a court order.^[8]

Emails can be sent in plain text or with end-to-end encryption. Emails sent between ProtonMail accounts are encrypted using the recipient's public encryption key. Emails sent to non-ProtonMail recipients can be encrypted with a predefined password, allowing the recipient to access the email in a separate web interface. Such emails can optionally self-destruct after a period of time.^[9]

Servers

Architecture of a ProtonMail datacenter.

Lausanne

Attinghausen

Map depicting the locations of ProtonMail servers in Switzerland.

ProtonMail maintains and owns their server hardware and network in order to avoid trusting a third party. They maintain two redundant data centres in Lausanne and Attinghausen (in the former K7 military bunker^[10]), Switzerland. Each datacenter uses load balancing across web, mail, and SQL servers, redundant power supply, hard drives with full disk encryption, and exclusive use of Linux and other open-source software.^[11] Their main datacenter is located under 1,000 meters of granite rock.^[9][12] In December 2014, ProtonMail has joined the RIPE NCC in an effort to have more direct control over the surrounding Internet infrastructure.^[13]

Since the data centres are located in Switzerland, they are legally outside of US and EU jurisdiction. Under Swiss law, all surveillance requests from foreign countries must go through a Swiss court, are subject to international treaties, and surveillance targets are notified and may appeal the request in court. Additionally, ProtonMail is outside the scope of the Swiss Federal Act on the Surveillance of Postal and Telecommunications Traffic, a law which governs lawful Swiss interception of electronic communications.^[14]

Security

ProtonMail uses a combination of public-key cryptography and symmetric encryption protocols to offer end-to-end encryption. When a user creates a ProtonMail account, their browser generates a pair of public and private RSA keys. The public key is used to encrypt the user's emails and other user data. The private key, which is capable of decrypting the user's data, is symmetrically encrypted with the user's mailbox password in the user's web browser using AES-256. The public key and the encrypted private key are then both stored on ProtonMail servers. Thus, ProtonMail stores decryption keys only in their encrypted form, so ProtonMail developers are unable to retrieve user emails or reset user mailbox passwords.^[15]

An email sent from one ProtonMail account to another is automatically encrypted with the public key of the recipient. Once encrypted, only the private key of the recipient can decrypt the email. When the recipient logs in, their mailbox password decrypts their private key and unlocks their inbox. Emails sent from ProtonMail to non-ProtonMail email addresses may be sent with or without encryption. With encryption, the email is encrypted with AES under a user-supplied password and then stored on ProtonMail's servers. The recipient receives a link to the ProtonMail website on which they can enter the password and read the decrypted email. ProtonMail assumes that the sender and the recipient have exchanged this password through a back channel.^[15]

ProtonMail exclusively supports HTTPS and uses TLS with ephemeral key exchange to encrypt all Internet traffic between users and ProtonMail servers. Their 4096-bit RSA SSL certificate is signed by QuoVadis Trustlink Schweiz AG and supports Extended Validation, Certificate Transparency,^[16] Public Key Pinning, and Strict Transport Security. Protonmail.com holds an "A+" rating from Qualys SSL Labs.^[17]

In September 2015, ProtonMail added native support to their web interface and mobile app for Pretty Good Privacy (PGP). This allows a user to export their ProtonMail PGP-encoded public key to others outside of ProtonMail, enabling them to use the key for email encryption. The ProtonMail team plans to support PGP encryption from ProtonMail to outside users.^[18]

ProtonMail currently supports two-factor authentication for its login process.^[19]

Interface

ProtonMail provides a web interface for accessing user emails, contacts, and user settings. The default layout of the interface places mailbox folders along the left side of the screen, a search bar and controls across the top, and email messages in the remaining space. The user also has the ability to provide a third-party theme and choose between two different styles for the email composition area and two different layouts for their Inbox.^[20][21] The source code for the web interface, including all client-side encryption methods, is available on GitHub under the MIT License.^[22]

History

Development

On 16 May 2014, ProtonMail entered into public beta.^[23] Within three days, ProtonMail was met with an overwhelming response and was forced to temporarily suspend beta signups while they worked to expand server capacity.^[24]

On 31 July 2014, ProtonMail received US$550,377 from 10,576 donors through a crowdfunding campaign on Indiegogo, while aiming for US$100,000.^[25] During the campaign, PayPal froze ProtonMail's PayPal account, thereby preventing the withdrawal of US$251,721 worth of donations. PayPal stated that the account was frozen due to doubts of the legality of encryption, statements that opponents said were unfounded.^[26][27] The restrictions were lifted the following day.^[28]

On 18 March 2015, ProtonMail received US$2 million from Charles River Ventures and the Fondation Genevoise pour l'Innovation Technologique (Fongit).^[29]

On 13 August 2015, ProtonMail released version 2.0, which was the most significant update in ProtonMail's history and included a new codebase for its web interface and introduced significant performance enhancements. The ProtonMail team simultaneously released the source code for the web interface under an open-source license.^[30]

On 17 March 2016, ProtonMail released version 3.0, which saw the official launch of ProtonMail out of beta. With a new interface for the web client, version 3.0 also included the public launch of ProtonMail's iOS and Android beta applications. These applications are built natively for each respective platform maintaining the gestures and actions familiar with each operating system.^[31] The mobile apps proved to be a hit with reports of increased efficiency and the ability to leave other email providers such as Gmail due to the usability and feature set found in ProtonMail. After receiving hundreds of thousands of downloads in the first week and thousands of reviews, the ProtonMail mobile apps garnered the highest ranking score in the app and play store.^[32]

2015 DDoS attacks

From 3 to 7 November 2015, ProtonMail was under several DDoS attacks that made the service largely unavailable to users.^[33] ProtonMail believed that it was affected by two separate attacks, the first led by a group of hackers known as the Armada Collective and the second by an unknown, more technically advanced group with abilities similar to a state-sponsored group. The first attack was tied to a ransom of 15 Bitcoins (roughly US$6,000) which ProtonMail eventually paid due to pressure from ISPs and other companies affected by the attack. The DDoS attacks, however, did not stop and instead began to take on more sophistication, with rates exceeding 100 Gbit/s. The company received an email from the Armada Collective in which they denied responsibility for the ongoing attack.^{[34][35][36][37]} During the attack, the company stated on Twitter that it was looking for a new data centre in Switzerland, saying that "many are afraid due to the magnitude of the attack against us". They have since posted that they "have a comprehensive long term solution which is already being implemented".^[35][38]

See also

• Comparison of webmail providers
• Comparison of mail servers

References

External links

Wikimedia Commons has media related to ProtonMail.

• Official website
• Source code of ProtonMail's web client on GitHub