all-in-one privacy solution":["Proton Unlimited — комплексное решение для защиты данных"],"Black Friday":["Черная пятница"],"No ads. Privacy by default.":["Без рекламы. Гарантия конфиденциальности"],"People before profits":["Люди важнее прибыли"],"Security through transparency":["Безопасность, основанная на прозрачности"],"The best Proton Mail ${ BLACK_FRIDAY } deals":["${ BLACK_FRIDAY }: лучшие предложения Proton Mail"],"The world’s only community- supported email service":["Единственный в мире сервис электронной почты с поддержкой сообщества"]},"specialoffer:limited":{"${ hours } hour":["${ hours } час","${ hours } часа","${ hours } часов","${ hours } часа"],"${ hoursLeft }, ${ minutesLeft } and ${ secondsLeft } left":["Осталось ${ hoursLeft }, ${ minutesLeft } и ${ secondsLeft }"],"${ minutes } minute":["${ minutes } минута","${ minutes } минуты","${ minutes } минут","${ minutes } минуты"],"${ seconds } second":["${ seconds } секунда","${ seconds } секунды","${ seconds } секунд","${ seconds } секунды"],"Limited time offer":["Ограниченное по времени предложение"]},"specialoffer:listitem":{"Create multiple addresses":["Создавайте несколько адресов"],"Hide-my-email aliases":["Создавайте алиасы hide-my-email"],"Quickly unsubscribe from newsletters":["С легкостью отменяйте подписку на рассылки"],"Use your own domain name":["Используйте собственное доменное имя"]},"specialoffer:logos":{"As featured in":["О нас в СМИ"]},"specialoffer:metadescription":{"Get an encrypted email that protects your privacy":["Электронная почта, защищающая вашу конфиденциальность"]},"specialoffer:metatitle":{"Proton Mail Black Friday Sale - Up to 40% off":["Черная пятница в Proton Mail: скидки до 40 %"]},"specialoffer:newmetadescription":{"Get up to 40% off Proton Mail subscriptions this Black Friday. Find great deals on our secure end-to-end encrypted email plans.":["Получите Proton Mail со скидкой до 40 %. Не пропустите выгодные предложения на планы безопасной электронной почты, зашифрованной сквозным шифрованием, в честь «черной пятницы»."]},"specialoffer:newmetatitle":{"Proton Mail Black Friday sale | Up to 40% off secure email":["«Черная пятница» в Proton Mail | Скидки до 40 %"]},"specialoffer:note":{"* Billed at ${ TOTAL_SUM } for the first year":["* ${ TOTAL_SUM } за первый год."],"*Billed at ${ TOTAL_SUM } for the first 2 years":["* ${ TOTAL_SUM } за первые два года."],"30-day money-back guarantee":["Гарантия возврата средств в течение 30 дней"],"Billed at ${ TOTAL_SUM } for the first 2 years":["${ TOTAL_SUM } за первые 2 года"],"Billed at ${ TOTAL_SUM } for the first year":["${ TOTAL_SUM } за первый год"],"You save ${ SAVE_SUM }":["Вы экономите ${ SAVE_SUM }."]},"specialoffer:off":{"${ PERCENT_OFF } off":["–${ PERCENT_OFF }"]},"specialoffer:testimonial":{"I love my ProtonMail":["Обожаю ProtonMail!"],"My favorite email service":["Мой любимый сервис электронной почты"],"Thanks Proton for keeping us all safe in the complicated internet universe.":["Спасибо Proton за защиту в запутанном интернет-пространстве."],"You get what you pay for. In the case of big tech, if you pay nothing, you get used. I quit using Gmail and switched to @ProtonMail":["Полностью оправданное вложение денег. Бигтех-компании используют тебя, если ты им не платишь. Поэтому я перешла с Gmail на @ProtonMail."]},"specialoffer:time":{"Days":["дн."],"Hours":["ч."],"Min":["мин."]},"specialoffer:title":{"And much more":["И многое другое"],"Safe from trackers":["Защита от трекеров"],"Stay organized":["Будьте организованными"],"Black Friday email deals":["Безопасная почта для покупок в «черную пятницу»"],"Don’t just take our word for it":["Отзывы наших клиентов"],"Make your inbox yours":["Сделайте свой почтовый ящик вашим"],"Our story":["Наша история"],"Transfer your data from Google in one click":["Перенесите данные из Gmail в одно нажатие"]},"specialoffer:tooltip":{"Access blocked content and browse privately. Includes ${ TOTAL_VPN_SERVERS }+ servers in ${ TOTAL_VPN_COUNTRIES }+ countries, connect up to 10 devices, access worldwide streaming services, malware and ad-blocker, and more.":["Сохраняйте конфиденциальность в интернете и получайте доступ к заблокированному контенту. Включает ${ TOTAL_VPN_SERVERS } серверов более чем в ${ TOTAL_VPN_COUNTRIES } странах с возможностью подключения на 10 устройствах, доступ к стриминговым платформам со всего мира, блокировщик рекламы, функцию защиты от вредоносных программ и другие преимущества."],"Easily share your calendar with your family, friends or colleagues, and view external calendars.":["Предоставляйте доступ к календарю родственникам, друзьям и коллегам, а также просматривайте календари других сервисов"],"Includes support for 1 custom email domain, 10 email addresses, 10 hide-my-email aliases, calendar sharing, and more.":["Включает поддержку 1 пользовательского домена, 10 адресов электронной почты, 10 алиасов hide-my-email, совместный доступ к календарю и другие преимущества."],"Includes support for 3 custom email domains, 15 email addresses, unlimited hide-my-email aliases, calendar sharing, and more.":["Включает поддержку трех пользовательских доменов, 15 адресов электронной почты, неограниченного числа алиасов hide-my-email, совместный доступ к календарю и другие преимущества."],"Manage up to 25 calendars, mobile apps, secured with end-to-end encryption, 1-click calendar import from Google, and more.":["До 25 календарей, мобильные приложения, сквозное шифрование, удобный перенос данных из Google Календаря и другие преимущества"]},"Status Banner":{"At the moment we are experiencing issues with the Proton VPN service":["При использовании сервиса Proton VPN могут возникать проблемы"]},"Status banner":{"Learn more":["Подробнее"],"Please note that at the moment we are experiencing issues with the ${ issues[0] } service.":["Сейчас при использовании сервиса ${ issues[0] } могут возникать проблемы."],"We are experiencing issues with one or more services at the moment.":["При использовании одного или нескольких сервисов могут возникать проблемы."]},"steps":{"Step":["Шаг"]},"suggestions":{"Suggestions":["Предложения"]},"Support":{"Sub category":["Подкатегория","Подкатегории","Подкатегорий","Подкатегорий"]},"Support article":{"${ readingTime } min":["${ readingTime } мин.","${ readingTime } мин.","${ readingTime } мин.","${ readingTime } мин."],"Category":["Категория","Категории","Категорий","Категорий"],"Didn’t find what you were looking for?":["Не нашли желаемый контент?"],"General contact":["Общие контакты"],"Get help":["Получить помощь"],"Legal contact":["Контакты юридического отдела"],"Media contact":["Контакты для прессы"],"Partnerships contact":["Контакты по вопросам партнерства"],"Reading":["Чтение"]},"Support Form Platform option":{"VPN for Android TV":["VPN для Android TV"],"VPN for Apple TV":["VPN для Apple TV"],"VPN for Chromebook":["VPN для Chromebook"]},"Support troubleshooting":{"App version":["Версия приложения"],"Browser":["Браузер"],"Check if this helps":["Возможно, нужный ответ найдется здесь"],"Choose a product":["Выберите продукт"],"Did this solve your issue?":["Удалось ли нам решить вашу проблему?"],"Faster assistance is just a few clicks away":["Пара нажатий, и вы получите быструю помощь"],"How can we help?":["Чем мы можем помочь?"],"No, contact support":["Нет, связаться со службой поддержки"],"Please fill out one field after another":["Заполните поля по порядку"],"Please make your selections":["Отметьте подходящие варианты"],"Proton account":["Аккаунт Proton"],"Proton for Business":["Proton for Business"],"Thank you for your feedback":["Спасибо за отзыв!"],"What can we help with?":["Какая помощь требуется?"],"Yes":["Да"]},"support_modal_search_query":{"Search query":["Поисковый запрос"]},"support_search_button":{"Search":["Найти"]},"support_search_i_am_looking_for":{"I'm looking for":["Я ищу"]},"SupportForm":{"For a faster resolution, please report the issue from the Bridge app: Help > Report a problem.":["Чтобы быстро устранить проблему в приложении Bridge, выберите «Справка» > «Сообщить о проблеме»."],"Information":["Информация"]},"SupportForm:option":{"Account Security":["Безопасность аккаунта"],"Contacts":["Контакты"],"Custom email domain":["Пользовательский домен адреса электронной почты"],"Email delivery and Spam":["Доставка электронных писем и спам"],"Encryption":["Шифрование"],"Login and password":["Имя пользователя и пароль"],"Merge aliases and accounts":["Объединение псевдонимов и аккаунтов"],"Migrate to Proton":["Переход на Proton"],"Notifications":["Уведомления"],"Other":["Другое"],"Plans and billing":["Тарифы и оплата"],"Proton for Business":["Proton for Business"],"Sign up":["Регистрация"],"Storage":["Хранилище"],"Users, addresses, and identities":["Пользователи, адреса и личные данные"]},"SupportForm:optionIntro":{"Select a topic":["Выберите тему"]},"Testimonial":{"Awards":["Награды"],"Customers":["Клиенты"],"Featured":["Что о нас говорят"],"Go to testimonial source":["Перейти к источнику отзыва"],"Open source of award":["Узнать, кто выдал награду"],"Open source of quote":["Узнать, откуда цитата"],"Reviews":["Отзывы"],"Videos":["видео."],"Watch on TikTok":["Смотреть в TikTok"],"Watch on YouTube":["Смотреть на YouTube"]},"TestimonialCategory":{"Awards":["Награды"],"Customers":["Клиенты"],"Featured":["Что о нас говорят"],"Media":["СМИ"],"Reviews":["Отзывы"],"Videos":["видео."]},"Text":{"If you need help, check out our ${ supportLink }.":["Если вам нужна помощь, перейдите в ${ supportLink }."],"The page you’re looking for might have been removed, or it could be an\nold link.":["Возможно, страница удалена\nили у вас устаревшая ссылка."],"Your question may already have an answer in our knowledge base:":["Возможно, ответ на ваш вопрос уже есть в нашей базе знаний:"]},"Title":{"On this page":["На этой странице"],"Page not found":["Страница не найдена"],"Related articles":["Статьи по теме"],"Share ${ thisPage }":["Поделиться ${ thisPage }"],"Switch to Proton Pass - Contact us":["Переход на Proton Pass — свяжитесь с нами"],"Thank you!":["Спасибо!"],"this page":["этой 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Proton Mail Bridge is a desktop application that runs in the background on your computer and encrypts and decrypts your mail as it enters and leaves your device. It allows for full integration of your Proton Mail account with email clients like Microsoft Outlook, Mozilla Thunderbird, and Apple Mail.
This document discusses how Bridge handles sensitive information, describes its potential attack vectors, and explains the security features that mitigate these attacks. (Note: This security model applies to the Bridge application for Linux, macOS, and Windows.)
This security model is technical in nature, but was written in plain language so that the average user can understand the important takeaways. You can also read more about what Proton Mail is and is not designed to protect you from in the Proton Mail threat model(новое окно).
As part of normal, day-to-day operations, Bridge must handle different types of data with varying levels of sensitivity. This data includes (but is not limited to):
User credentials and an access token for authentication with the Proton servers
Public and private keys for sending and reading messages
Encrypted messages, attachments, and metadata
We explain how Bridge secures this sensitive data in greater detail below.
Your passwords never leave your machine Users log in to Bridge, which in turn authenticates with the Proton Mail API using the Secure Remote Password protocol(новое окно). This authentication process ensures a user’s password never leaves their machine, and it generates an access token and a refresh token.
The access token is relatively short-lived and is used to authenticate any subsequent API requests; it is stored in the device’s memory. The refresh token is used to generate new access tokens and is stored securely in the operating system’s keychain (Windows Credentials Manager, macOS Keychain, or pass/gnome-keyring on Linux). The user’s hashed and salted mailbox password (used to decrypt their PGP keys) and Bridge password (used to connect an email client to Bridge) are also held in the operating system’s keychain.
Ensuring a secure connection to Proton servers Bridge communicates with the Proton Mail API over an encrypted TLS connection. It additionally employs TLS certificate public key pinning to ensure it only connects to trusted Proton Mail servers. If Bridge receives an untrusted public key, it will assume an unknown intermediary is pretending to be a Proton server and immediately warn the user.
Bridge never stores or shares a user’s PGP keys After the user logs in, Bridge downloads their encrypted, private PGP keys from the Proton servers and unlocks them. These keys are held in the device’s memory, never on disk. Whenever a user turns off their device, they wipe its memory. This makes it unlikely an attacker will be able to obtain a copy of a user’s PGP keys, even if they steal the user’s device. These keys are also never shared with other applications on your device and stay within Bridge’s memory space.
Bridge does not store decrypted message data When an IMAP client requests a message body or attachment, it is downloaded from the Proton servers as an encrypted PGP message, decrypted locally, and then transmitted to the IMAP client. Similar to the user’s PGP keys, Bridge does not permanently store any message bodies or attachments to disk, further reducing the amount of sensitive data available on the device.
Attack mitigation
Here we describe the potential attack vectors of Bridge and how we mitigate these attacks.
Reducing the threat of a MITM attack
As described, Bridge employs TLS certificate pinning, which mitigates the risk of a network-level man-in-the-middle (MITM) attack.
Furthermore, the content of messages sent from Bridge to Proton Mail users or external recipients using PGP has an additional layer of protection thanks to end-to-end encryption. This means Bridge encrypts the user’s message before it leaves their device. The message remains encrypted until it reaches the recipient’s device, which decrypts it. This prevents any third party, including Proton Mail, from accessing the content of a user’s message. Messages sent this way remain inaccessible because a user’s mailbox password never leaves their device and, thus, is never transmitted to an attacker.
Secure updates
Bridge on Windows and macOS includes a feature that allows it to self-update. The update process has additional safeguards in place to verify that only trusted versions of Bridge that are created and signed by Proton Mail are installed.
Bridge recommended use cases
Bridge is a unique tool when compared to the other Proton Mail apps. As such, there are specific cases in which it would be more practical and useful than other Proton Mail apps.
Below are some examples of recommended use cases for Bridge:
Offline editing If you find yourself without a stable Internet connection, you can use your favorite email client with Bridge to download emails while you do have good Internet access and then process them offline later. Most email clients will automatically send and receive your drafts once you are back online.
Offline backups of your emails are required If you need to have offline copies of your messages for whatever reason, Bridge is the easiest way to accomplish this. The Bridge app enables your IMAP/SMTP client to do this automatically if you choose to do so.
Add Proton Mail security to already known email clients If you or your staff do not feel confident learning how to use a new email service, Bridge lets you add Proton Mail encryption to your messages while continuing to use your favorite IMAP/SMTP email client. These clients include Outlook, Thunderbird, and Apple Mail, all applications that many people are familiar with. This means that once you set up Bridge, using it does not require any new training.
Bridge security model scope
No application is 100% secure, and no piece of software can protect its user against every potential threat. Proton Mail Bridge is engineered to provide additional protection to its users’ data, but certain conditions are outside of the scope of the security model.
User device security We assume users run the Bridge app in a safe environment. For instance, we assume that Bridge program files are installed to a location where normal (non-admin) users have no write privileges. Furthermore, we expect the user’s device to be free of any malicious software (keyloggers, screen recorders, memory scanners, etc.) that could access the device’s data in memory or on disk. Bridge, unfortunately, cannot secure your data if your device is already compromised.
Additionally, we assume that the IMAP/SMTP ports that the email client connects to are not exposed beyond the device that Bridge is running on. The Bridge application ignores all connections that do not originate from the localhost, and we assume the user will not attempt to circumvent this.
Bridge installer security We assume that the user securely downloaded the Bridge installer from our server (the server should present a valid and expected SSL certificate). For Windows and macOS, the operating system inspects the signatures on the installer file automatically before installation. It then displays the results to the user, which we assume they properly verify. We recommend Linux users refer to our support article on Verifying the Proton Mail Bridge package(новое окно) for instructions. If you download the Bridge application from an unauthorized source, we cannot guarantee the safety of the installer.
Our recommendations for keeping your device secure
We have invested heavily in the security of our Bridge app. You can help maximize the security of your own device by taking a few simple measures:
Encrypt your device’s hard drive. Windows(новое окно) and macOS(новое окно) devices all have built-in encryption systems, but you have to turn them on. Once you have encrypted your drive, write down your recovery code and store it in a secure place.
Enable your operating system’s antivirus protection, if available.
Ensure your network ports are secured by a firewall to prevent outside machines from connecting to them.
Do not install untrusted programs on your device. This includes unknown open source versions of Bridge. Downloading Bridge directly from Proton Mail(новое окно) is the safest option.
Do not open links or download attachments from untrusted senders.
Conclusion
Our first priority is always our users’ security. Our goal is to make it easy for anyone to protect their privacy by creating tools that apply advanced cryptography to their messages automatically. The Bridge tool was designed to add additional security to already existing IMAP/SMTP email clients. By keeping your device secure, you can use these email clients and still take charge of your data. Thank you for your support!
Proton Mail and Proton VPN are funded by community contributions. If you would like to support our development efforts, you can upgrade to a paid plan(новое окно). Thank you for your support.
Безопасная электронная почта и защита вашей конфиденциальности
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