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FlowCrypt Software Specifications

FlowCrypt Browser Extension

Purpose End-to-end OpenPGP encryption of email hosted on Gmail
Programming languages TypeScript, JavaScript
Release Channel Stable (Production ready)

Core functionality

  1. Import OpenPGP private keys created by the customer’s legacy software.
  2. Send OpenPGP encrypted emails to other FlowCrypt users.
  3. Send OpenPGP encrypted attachments to other FlowCrypt users.
  4. Decrypt and view OpenPGP encrypted emails received from other FlowCrypt users.
  5. Decrypt and download OpenPGP encrypted attachments received from other FlowCrypt users.

Additional functionality

  1. Send encrypted emails to users of other OpenPGP-compatible software.
  2. Send encrypted attachments to users of other OpenPGP-compatible software.
  3. Decrypt and view encrypted messages received from other OpenPGP-compatible software users.
  4. Decrypt and download encrypted attachments received from users of other OpenPGP-compatible software.
  5. Manually change or update public keys in the application Contacts section.
  6. View information about the user’s public key.
  7. Look up the public keys of other FlowCrypt users.
  8. Verify that public key records match the installed private key.
  9. Sign encrypted emails to let your recipients verify that the message is from you and that the content hasn’t been modified. Sign-only key support is available.
  10. Copy the public key to the clipboard, or to a file.
  11. Import private keys from a file or clipboard.
  12. Backup private keys.

Known limitations

  1. Attachments can’t exceed 25MB per email.
  2. Messages and attachments encrypted for a public key that doesn’t match the user’s private key can’t be opened.
  3. Messages and keys not strictly adhering to OpenPGP standards may not be supported.
  4. Certain non-default Chrome settings may cause FlowCrypt to stop functioning. Rigorous testing is strongly recommended before deploying changes to Chrome settings.
  5. May not be compatible with all OpenPGP software from other vendors. Work is underway to increase compatibility over time.

Please see Known Limitations for a more specific list.

Required system configuration

  1. Modern, up-to-date operating system: Windows 10 or newer, MacOS 10.14 or newer, Ubuntu 18.04 or newer.
  2. Up-to-date Google Chrome browser.
  3. Ability to install and use Chrome Extensions.
  4. Default Google Chrome settings.
  5. Storage persistence across user sessions.
  6. Minimum 1GB of free disk space.
  7. Minimum 1GB of free RAM.
  8. Minimum dual core x86 CPU.
  9. Stable internet connection, working mouse, keyboard, and monitor.

Environment deprecation

The latest three major stable versions of Google Chrome will remain supported.

Open-source software

The list of OSS used by and distributed with FlowCrypt Browser Extension.

Software Purpose License Type
OpenPGP.js Encryption library LGPL 3.0
OpenPGP.js/Web Stream Tools Stream Manipulation Library MIT License
Forge Cryptographic library BSD License
GPL Version 2
zxcvbn Password Strength Estimator MIT License
emailjs-mime-builder Email Library MIT License
emailjs-mime-codec Email Library MIT License
emailjs-mime-parser Email Library MIT License
emailjs-mime-types Email Library MIT License
emailjs-addressparser Email Library MIT License
emailjs-stringencoding
adapted from inexorabletash 		Email Library Unlicense
Mozilla Public License 2.0
mailparser Email Library MIT License
Punycode.js Punycode Converter MIT License
iso-8859-2 Character Encoding and Manipulation Library MIT License
FineUploader File Uploading Library MIT License
Blob.js Large File Manipulation Library MIT License
Clipboard.js Copy to Clipboard Library MIT License
filesize.js File Size Conversion Library 3-Clause BSD License
PDF.js PDF Manipulation Library Apache License 2.0
DOMPurify DOM Sanitization Library Apache License 2.0
Mozilla Public License 2.0
jQuery DOM Manipulation Library MIT License
Linkify Link Detecting Library MIT License
Bootstrap UI Library MIT License
Squire Rich Text Editor MIT License
sweetalert2 Popup Dialog Library MIT License

FlowCrypt Android App

Purpose End-to-end OpenPGP encryption of email
Programming languages Kotlin/JVM
Release Channel Stable (Production ready)

Core functionality

  1. Import OpenPGP private keys created by the customer’s legacy software.
  2. Send OpenPGP encrypted emails to other FlowCrypt users.
  3. Send OpenPGP encrypted attachments to other FlowCrypt users.
  4. Decrypt and view OpenPGP encrypted emails received from other FlowCrypt users.
  5. Decrypt and download OpenPGP encrypted attachments received from other FlowCrypt users.

Additional functionality

  1. Send encrypted emails to users of other OpenPGP-compatible software.
  2. Send encrypted attachments to users of other OpenPGP-compatible software.
  3. Decrypt and view encrypted messages received from other OpenPGP-compatible software users.
  4. Decrypt and download encrypted attachments received from users of other OpenPGP-compatible software.
  5. Manually change or update public keys in the application Contacts section.
  6. View information about the user’s public key.
  7. Look up other FlowCrypt users’ public keys.
  8. Verify that public key records match the installed private key.
  9. Sign encrypted emails to let your recipients verify that the message is from you and that the content hasn’t been modified.
  10. Copy the public key to the clipboard, or to a file.
  11. Import private keys from a file or clipboard.
  12. Backup private keys.

Known limitations

  1. Attachments can’t exceed 25MB per email.
  2. Messages and attachments encrypted for a public key that doesn’t match the user’s private key can’t be opened.
  3. Messages and keys not strictly adhering to OpenPGP standards may not be supported.
  4. Certain Android System settings may cause FlowCrypt Android App to stop functioning. Rigorous testing is strongly recommended before deploying changes to Android settings.
  5. May not be compatible with all OpenPGP software from other vendors.

Required system configuration

  1. Modern smartphone running Android with standard Android 8.0 or higher.
  2. Minimum 1GB of free disk space.
  3. Minimum 2GB of free RAM.
  4. Stable 1Mbit or faster internet connection.

Environment deprecation

The latest five major stable versions of Android app will remain supported.

Open-source software

The list of software used by and distributed with FlowCrypt Android Application.

Software Purpose License Type
PGPainless Core Encryption Lybrary Apache License 2.0
JOSE4J Security Library Apache License 2.0
OWASP Java HTML Sanitizer Security Library Apache License 2.0
AppAuth Authentication Library Apache License 2.0
ACRA HTTP Crash Reporting Library Apache License 2.0
Jakarta Mail Email Framework Custom License
Jakarta Activation Mail Library Custom License
RawHTTP HTTP Library Apache License 2.0
OkHttp Logging Interceptor HTTP Library Apache License 2.0
Google APIs Client Library for Java API Client Library Apache License 2.0
Google API Services Gmail API Client Library Apache License 2.0
AndroidX Legacy API Support Library Apache License 2.0
AndroidX Appcompat API Support Library Apache License 2.0
AndroidX Core API Support Library Apache License 2.0
AndroidX Activity API Access Library Apache License 2.0
Retrofit HTTP client, Data Conversion Apache License 2.0
ZBase32 Commons Codec Z-Base-32 Converter Apache License 2.0
Gson Data Conversion Library Apache License 2.0
Okio Data Input/Output library Apache License 2.0
Gson Data Manipulation Library Apache License 2.0
Jsoup HTML Manipulation Library MIT License
Google Play Services Base Google Play Services Component -
Google Play Services Auth Google Play Services Component -
Kotlin Coroutines Kotlin Coroutines Library Apache License 2.0
Auto Service Source Code Generator Apache License 2.0
AndroidX Lifecycle Utility Library Apache License 2.0
Commons IO Utility Library Apache License 2.0
PhotoEditor PhotoEditor MIT License
GPUImage for Android Image Manipulation Library Apache License 2.0
AndroidX Paging Paging Library Apache License 2.0
AndroidX Browser Browser Communication Library Apache License 2.0
Material Components for Android UI Library Apache License 2.0
FlexboxLayout UI Library Apache License 2.0
Overscroll Decor Android UI Library BSD 2-Clause “Simplified” License
AndroidX Fragment UI Library Apache License 2.0
AndroidX Cardview UI Library Apache License 2.0
AndroidX Recyclerview UI Library Apache License 2.0
AndroidX Constraintlayout UI Library Apache License 2.0
AndroidX Preference UI Library Apache License 2.0
AndroidX Navigation UI Library Apache License 2.0
AndroidX Webkit UI Library Apache License 2.0

FlowCrypt iOS App

Purpose End-to-end OpenPGP encryption of email
Programming languages Swift, Typescript
Release Channel Stable (Production ready)

Core functionality

  1. Import OpenPGP private keys created by the customer’s legacy software.
  2. Send OpenPGP encrypted emails to other FlowCrypt users.
  3. Send OpenPGP encrypted attachments to other FlowCrypt users.
  4. Decrypt and view OpenPGP encrypted emails received from other FlowCrypt users.
  5. Decrypt and download OpenPGP encrypted attachments received from other FlowCrypt users.

Additional functionality

  1. Send encrypted emails to users of other OpenPGP-compatible software.
  2. Send encrypted attachments to users of other OpenPGP-compatible software.
  3. Decrypt and view encrypted messages received from other OpenPGP-compatible software users.
  4. Decrypt and download encrypted attachments received from users of other OpenPGP-compatible software.
  5. View information about the user’s public key.
  6. Verify that public key records match the installed private key.
  7. Sign encrypted emails to let your recipients verify that the message is from you and that the content hasn’t been modified.
  8. Copy the public key to the clipboard, or to a file.
  9. Import private keys from a file or clipboard.
  10. Backup private keys.

Known limitations

  1. Attachments can’t exceed 25MB per email.
  2. Messages and attachments encrypted for a public key that doesn’t match the user’s private key can’t be opened.
  3. Messages and keys not strictly adhering to OpenPGP standards may not be supported.
  4. Certain iOS System settings may cause FlowCrypt iOS App to stop functioning. Rigorous testing is strongly recommended before deploying changes to iOS settings.
  5. May not be compatible with all OpenPGP software from other vendors.

Required system configuration

  1. Any iPhone or iPod touch running iOS 15.0 or higher, iPad running iPadOS 15.0 or higher, or Mac running macOS 12.0 or higher with Apple M1 chip or higher.
  2. Minimum 1GB of free disk space.
  3. Minimum 2GB of free RAM.
  4. Stable 1Mbit or faster internet connection.

Environment deprecation

The latest two major stable versions of iOS will remain supported.

Open-source software

The list of packages used by and distributed with FlowCrypt iOS Application.

Software Purpose License Type
OpenPGP.js Encryption library LGPL 3.0
OpenPGP.js/Web Stream Tools Stream Manipulation Library MIT License
GoogleSignIn-iOS Security Library Apache License 2.0
IDZSwiftCommonCrypto Cryptographic Library MIT License
zxcvbn Password Strength Estimator MIT License
MailCore 2 Email Library BSD-License
Google APIs Client Library for Objective-C for REST JSON Manipulation Framework Apache License 2.0
encoding.js Character Encoding Library MIT License
Texture Performance Library Apache License 2.0
realm Mobile Database Apache License 2.0
sanitize-html HTML Sanitizer MIT License
MBProgressHUD UI Library MIT License
Toast-Swift UI Extension MIT License
Content © FlowCrypt a.s.
Layout from Cockroach Labs,CC Attr 4.0, edited