all-in-one privacy solution":["Proton Unlimited es una solución de privacidad todo en uno"],"Black Friday":["Black Friday"],"No ads. Privacy by default.":["Sin anuncios. Privacidad por defecto."],"People before profits":["Primero las personas, luego los beneficios"],"Security through transparency":["Seguridad con transparencia"],"The best Proton Mail ${ BLACK_FRIDAY } deals":["Las mejores ofertas de Proton Mail en el ${ BLACK_FRIDAY }"],"The world’s only community- supported email service":["El único servicio de correo electrónico del mundo financiado por la comunidad"]},"specialoffer:limited":{"${ hours } hour":["${ hours } hora","${ hours } horas"],"${ hoursLeft }, ${ minutesLeft } and ${ secondsLeft } left":["Tiempo restante: ${ hoursLeft }, ${ minutesLeft } y ${ secondsLeft }"],"${ minutes } minute":["${ minutes } minuto","${ minutes } minutos"],"${ seconds } second":["${ seconds } segundo","${ seconds } segundos"],"Limited time offer":["Oferta por tiempo limitado"]},"specialoffer:listitem":{"Create multiple addresses":["Cree múltiples direcciones"],"Hide-my-email aliases":["Seudónimos de hide-my-email"],"Quickly unsubscribe from newsletters":["Cancele suscripciones a boletines rápidamente"],"Use your own domain name":["Use su propio dominio"]},"specialoffer:logos":{"As featured in":["Tal como aparece en"]},"specialoffer:metadescription":{"Get an encrypted email that protects your privacy":["Obtenga un correo electrónico cifrado que protege su privacidad"]},"specialoffer:metatitle":{"Proton Mail Black Friday Sale - Up to 40% off":["Oferta de Black Friday de Proton Mail: hasta un 40% de descuento"]},"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.":["Aproveche las rebajas de Black Friday y obtenga suscripciones de Proton Mail con hasta un 40 % de descuento. Encontrará las mejores ofertas en planes de correo electrónico seguro cifrado de extremo a extremo."]},"specialoffer:newmetatitle":{"Proton Mail Black Friday sale | Up to 40% off secure email":["Rebajas de Black Friday en Proton Mail | Hasta un 40 % de descuento en correo electrónico seguro"]},"specialoffer:note":{"* Billed at ${ TOTAL_SUM } for the first year":["*Con un costo de ${ TOTAL_SUM } durante el primer año"],"*Billed at ${ TOTAL_SUM } for the first 2 years":["*Con un costo de ${ TOTAL_SUM } durante los primeros 2 años"],"30-day money-back guarantee":["Garantía de devolución de dinero de 30 días"],"Billed at ${ TOTAL_SUM } for the first 2 years":["Con un costo de ${ TOTAL_SUM } durante los primeros 2 años"],"Billed at ${ TOTAL_SUM } for the first year":["Con un costo de ${ TOTAL_SUM } durante el primer año"],"You save ${ SAVE_SUM }":["Ahorre ${ SAVE_SUM }"]},"specialoffer:off":{"${ PERCENT_OFF } off":["-${ PERCENT_OFF }"]},"specialoffer:testimonial":{"I love my ProtonMail":["Amo mi Proton Mail"],"My favorite email service":["Mi servicio de correo electrónico favorito"],"Thanks Proton for keeping us all safe in the complicated internet universe.":["Gracias Proton por mantenernos a salvo en el complicado universo de Internet."],"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":["Obtiene aquello por lo que paga. En el caso de la gran tecnología, cuando uno no paga nada, se acostumbra. Dejé de usar Gmail y cambié a @ProtonMail"]},"specialoffer:time":{"Days":["Días"],"Hours":["Horas"],"Min":["min"]},"specialoffer:title":{"And much more":["Y mucho más"],"Safe from trackers":["A salvo de rastreadores"],"Stay organized":["Mantenga todo en orden"],"Black Friday email deals":["Ofertas en correo electrónico del Black Friday"],"Don’t just take our word for it":["No confíe solo en nuestra palabra"],"Make your inbox yours":["Tome posesión de su bandeja de entrada"],"Our story":["Nuestra historia"],"Transfer your data from Google in one click":["Transfiera sus datos de Google con un solo clic"]},"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.":["Acceda a contenidos bloqueados y navegue de forma privada. Incluye más de ${ TOTAL_VPN_SERVERS } servidores en más de ${ TOTAL_VPN_COUNTRIES } países, se conecta con hasta 10 dispositivos, accede a servicios de transmisión de todo el mundo, bloquea malware y publicidad y mucho más."],"Easily share your calendar with your family, friends or colleagues, and view external calendars.":["Comparta su calendario con familiares, amigos y compañeros fácilmente y consulte calendarios externos."],"Includes support for 1 custom email domain, 10 email addresses, 10 hide-my-email aliases, calendar sharing, and more.":["Incluye compatibilidad con 1 dominio de correo electrónico personalizado, 10 direcciones de correo electrónico, 10 seudónimos de hide-my-email, posibilidad de compartir calendario, etc."],"Includes support for 3 custom email domains, 15 email addresses, unlimited hide-my-email aliases, calendar sharing, and more.":["Incluye compatibilidad con 3 dominios de correo electrónico personalizado, 15 direcciones de correo electrónico, seudónimos ilimitados de hide-my-email, posibilidad de compartir calendario, etc."],"Manage up to 25 calendars, mobile apps, secured with end-to-end encryption, 1-click calendar import from Google, and more.":["Administre hasta 25 calendarios, apps móviles, protegido con cifrado de extremo a extremo, importación de calendario con 1 clic desde Google y más."]},"Status banner":{"Learn more":["Más información"],"Please note that at the moment we are experiencing issues with the ${ issues[0] } service.":["Tenga en cuenta que, en este momento, estamos experimentando problemas con el servicio ${ issues[0] }."],"We are experiencing issues with one or more services at the moment.":["En este momento, tenemos problemas con uno o más servicios."]},"Status Banner":{"At the moment we are experiencing issues with the Proton VPN service":["En este momento, tenemos problemas con el servicio Proton VPN."],"Learn more":["Más información"]},"steps":{"Step":["Paso"]},"suggestions":{"Suggestions":["Sugerencias"]},"Support":{"Sub category":["Subacategoria","Subcategorías"]},"Support article":{"${ readingTime } min":["${ readingTime } minuto","${ readingTime } minutos"],"Category":["Categoría","Categorías"],"Didn’t find what you were looking for?":["¿No encontró lo que buscaba?"],"General contact":["Contacto general"],"Get help":["Obtener ayuda"],"Legal contact":["Contacto legal"],"Media contact":["Contacto para medios"],"Partnerships contact":["Contacto para colaboradores"],"Reading":["Lectura"]},"Support Form Platform option":{"VPN for Android TV":["VPN para Android TV"],"VPN for Apple TV":["VPN para Apple TV"],"VPN for Chromebook":["VPN para Chromebook"]},"Support troubleshooting":{"App version":["Versión de la app"],"Browser":["Navegador"],"Check if this helps":["Compruebe si le sirve"],"Choose a product":["Elija un producto"],"Did this solve your issue?":["¿Le ha resultado útil para resolver el problema?"],"Faster assistance is just a few clicks away":["Solo le separan unos clics de una asistencia más rápida"],"How can we help?":["¿Cómo podemos ayudarle?"],"No, contact support":["No, contactar a soporte"],"Please fill out one field after another":["Complete un campo después de otro"],"Please make your selections":["Realice sus selecciones"],"Proton account":["Cuenta de Proton"],"Proton for Business":["Proton for Business"],"Thank you for your feedback":["Gracias por sus comentarios"],"What can we help with?":["¿En qué podemos ayudarle?"],"Yes":["Sí"]},"support_modal_search_query":{"Search query":["Consulta"]},"support_search_button":{"Search":["Buscar"]},"support_search_i_am_looking_for":{"I'm looking for":["Busco"]},"SupportForm":{"For a faster resolution, please report the issue from the Bridge app: Help > Report a problem.":["Para una resolución más rápida, reporte el problema desde la app Bridge: Ayuda > Reportar un problema."],"Information":["Información"]},"SupportForm:option":{"Account Security":["Seguridad de la cuenta"],"Contacts":["Contactos"],"Custom email domain":["Dominio de correo electrónico personalizado"],"Email delivery and Spam":["Entrega de correo electrónico y spam"],"Encryption":["Cifrado"],"Login and password":["Inicio de sesión y contraseña"],"Merge aliases and accounts":["Combinar alias y cuentas"],"Migrate to Proton":["Migrar a Proton"],"Notifications":["Notificaciones"],"Other":["Otros"],"Plans and billing":["Planes y facturación"],"Proton for Business":["Proton for Business"],"Sign up":["Regístrese"],"Storage":["Almacenamiento"],"Users, addresses, and identities":["Usuarios, direcciones e identidades"]},"SupportForm:optionIntro":{"Select a topic":["Seleccione un tema"]},"Testimonial":{"Awards":["Premios"],"Customers":["Clientes"],"Featured":["Destacados"],"Go to testimonial source":["Ir a la fuente testimonial"],"Open source of award":["Abrir fuente del premio"],"Open 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you!":["¡Gracias!"],"this page":["esta página"]},"tooltip_vpn":{"Access blocked content and browse privately. Includes ${ TOTAL_VPN_SERVERS }+ servers in ${ TOTAL_VPN_COUNTRIES }+ countries, highest VPN speed, ${ TOTAL_VPN_CONNECTIONS } VPN connections, worldwide streaming services, malware and ad-blocker, and more.":["Acceda a contenidos bloqueados y navegue de forma privada. 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The following article presents a high-level overview of Proton Mail’s Android security model and explains how the app protects your sensitive data. You can view our Android app’s open-source code on GitHub(nueva ventana).
Read our threat model(nueva ventana) for more information on what threats Proton Mail is designed to counter.
Although this article covers technical subject matter, we wrote it to be as accessible as possible to the general audience.
Overview
The Proton Mail Android app stores as little data as possible on your device. This approach allows the app to provide higher data security and more efficiently use the device’s storage space. However, it does need to store some data locally. This data includes:
Encrypted messages (only messages opened since the last login are stored), attachments (only attachments viewed since the last login), and metadata
Public and private keys for encrypting and decrypting messages
Access tokens for communication with the Proton Mail API
User account details (e.g., username, time of last message, etc.)
Application and account settings
Miscellaneous preferences
The app keeps some of this data in secured (encrypted) key-value pairs or inside a local database. Almost all of this data is encrypted at rest.
Protection of application assets
User credentials
Although the username persists in the application, your password is neither persistent nor cached. After your enter your password, it is immediately delegated to the app’s internal Secure Remote Password (SRP) Protocol logic.
The application keeps databases in its private storage space where they are inaccessible to other applications, and all sensitive data is encrypted.
Secure shared preferences
One of Android’s mechanisms for storing application data is Shared Preferences, which, in a nutshell, stores data in key-value pairs. Because this data is kept in plaintext, we have added a custom encryption wrapper around it. This wrapper keeps all persistent data contained in our application’s preferences private and encrypted. Additionally, the keys used for the custom encryption wrapper are protected by the Android Keystore.
Require user approval to load embedded images and remote content
By default, the app blocks embedded images and remote content. You have to manually load them or disable this block in the app’s settings.
Attachments
Our app downloads regular attachments into the primary storage folder of the device (i.e., the Downloads folder). However, we handle other types of embedded and remote content somewhat differently:
Remote content (e.g., linked images) is never downloaded to persistent storage.
Embedded images are downloaded similarly to regular attachments, but they are kept in the application’s private storage (instead of a public directory).
Push notification encryption
Proton Mail’s push notification servers always encrypt the notifications they send, and the Proton Mail client decrypts these notifications locally. These notifications are never stored on the device.
Application auto-locking and biometrics
We have implemented a straightforward, PIN-based feature to automatically lock the application after a period of inactivity. Once the app is locked, it prompts the user to enter their PIN to unlock it. (You can activate this PIN protection in the settings.) If you choose this option, you can also open the app using the device’s own biometric authentication (you will have to have already registered your biometric data before your can override the PIN). This lets you benefit from the convenience of your device’s biometric scanners without lowering the security level of the app.
Updates
There are two ways to download and update the Proton Mail Android app. One is via the Google Play Store, which lets you take advantage of the update mechanism in Google Play to retrieve and apply app updates.
You can also download our app directly from our website as an APK file(nueva ventana). Alongside the download link, you can find the SHA-256 checksum they need to verify the APK file’s integrity.
Attack mitigation
Here we describe the potential attack vectors of the Android client and how we mitigate these attacks.
Web-based attacks
All emails are treated as HTML emails and are rendered by the WebView (android.webkit) component. Since all incoming messages could potentially contain malware, we have disabled JavaScript execution in the WebView configuration for incoming messages. On top of this, we do preprocessing and HTML sanitization to strip out any suspicious content.
Note: Like other mobile email apps, JavaScript execution is allowed in certain WebViews used by the app (e.g., a human verification CAPTCHA dialog) but never in the email content WebView.
We use the TrustKit-Android(nueva ventana) open-source library for certificate pinning to prevent an imposter server, even one equipped with an otherwise valid TLS certificate, from being able to pose as Proton Mail and intercept network traffic.
Attacks from a malicious app (sandboxed)
Android Lollipop 5.0, which included SELinux, was the first Android version to feature a strengthened Application Sandbox. Each subsequent major Android OS release came with improved application sandboxing, meaning a malicious application (assuming it does not have root privileges) poses very little threat to the Proton Mail Android app.
Android security model scope
No application can protect its users against every potential threat 100% of the time. Proton Mail Android provides additional protection for your data. However, certain conditions are outside of the scope of this security model.
User device security
We assume that users keep their Android devices secure. For instance, if an you root your device, we expect you to understand that this makes it much easier for malicious applications to bypass the restrictions of the Android application sandbox.
We also expect your device to be free of any malicious software (keyloggers, screen recorders, etc.) that could monitor your actions.
We do our best to protect your data even when your device is compromised. However, all security systems are more likely to fail if the device in question is already compromised.
Android protection
Our application attempts to leverage all of the most recent security improvements offered by the current Android operating system (OS). While our client supports a broad range of Android OS versions (all the way back to Android 5.0 Lollipop), we highly recommend you regularly update your Android OS so that you’re always using the most recent release.
Audits and open source
We released the Proton Mail Android client as free and open-source software under a GNU General Public License. The app has been audited by the respected security firm SEC Consult(nueva ventana). We have published the results of this audit(nueva ventana).
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(nueva ventana). Thank you for your support.