mirror of
https://github.com/amnesica/KryptEY.git
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108 lines
4.5 KiB
Markdown
108 lines
4.5 KiB
Markdown
<p align="center">
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<img src="static/logo/logo.png" height="150" title="KryptEY Logo">
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</p>
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<h1 align="center">KryptEY - Secure E2EE communication</h1>
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Keyboard for secure end-to-end-encrypted messages through the signal protocol in any messenger.
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Communicate securely and independent, regardless of the legal situation or whether messengers use
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E2EE. No server needed.
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KryptEY was created by [mellitopia](https://github.com/mellitopia)
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and [amnesica](https://github.com/amnesica).
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## Motivation
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Breaking of end-to-end encryption (E2EE) by laws such as the planned EU chat control is an ongoing
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issue. Content in messengers that use E2EE, such as Whatsapp or Signal, could thus be monitored by
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third parties. E2EE is often, but not always, standard in messengers. There are proven methods for
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E2EE such as PGP. However, these methods are sometimes cumbersomely integrated and require a lot of
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effort to use.
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KryptEY is an Android keyboard that implements the Signal protocol. The keyboard works
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messenger-independently and both the X3DH Key Agreement Protocol and the Double Ratchet Algorithm
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work without a server, thus it enables a highly independent use of the protocol.
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## Features
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Based upon the [Simple Keyboard](https://github.com/rkkr/simple-keyboard) KryptEY adds a view above
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the Keyboard for the E2EE functionality.
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- use E2EE through Signal Protocol in any messenger
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- encryption/decryption of messages
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- enter message through separate text field in keyboard
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- use clipboard to read messages
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- manage contacts in own contact list in keyboard
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- message log to view sent/received messages
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- send messages as plain JSON (raw mode) or hidden in a decoy text (fairytale mode)
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- verification of E2EE functionality via fingerprint
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- Q&A View helps with questions
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- Dark & light theme
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See [this](/KRYPTEY.md) document for further information on how KryptEY is working.
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## Demo
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Conversation between Alice (right) and Bob (left) in the Signal Messenger using KryptEY.
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<div style="display:flex;" align="center">
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<img alt="App image" src="static/screenshots/demo.gif" width="80%">
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</div>
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## Download
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<a href='https://github.com/amnesica/KryptEY/releases'><img alt='Get it on Github' src='static/github/get-it-on-github.png' height='60'/></a>
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If you need instructions on how to use the app, see our help [here](/HELP.md)
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## Privacy
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Read our privacy statement [here](/PRIVACY.md)
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## Permissions
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- VIBRATE: Required for vibrations on key press
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## Security
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The existing security properties for the Signal Protocol are also valid for the keyboard.
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The elliptic curve X25519 with SHA-512 is used in the X3DH Key Agreement Protocol from the applied
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Signal library. The hash function SHA-256 is used for the various chains and AES-256 with CBC (
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Pkcs#7) is used for the encryption of the messages. SHA-512 is also used to generate the
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fingerprint, the representation of the public key used for encryption.
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## Limitations
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The keyboard was designed as a POC and only allows 1-to-1 conversations. However, the application
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can also be used in a group chat to a limited extent. Here, a message can be directed to a
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specific chat partner and not to all people. Other participants of the group chat cannot decrypt
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the message.
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Text messages in Telegram are getting copied as HTML and not as plain text. When decoding the
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message with the fairytale mode the copied message is compromised and can't be read properly.
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Therefore, it can't be decoded at all. However, the raw mode works properly. When using KryptEY
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with Telegram we recommend the raw mode.
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Some messengers like Threema only allows up to 3500 bytes per message. Therefore, different
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character input limitations apply. To stay under the 3500 bytes limit, only 500 characters are
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allowed for raw and fairytale mode. For convenience these limitation applies for all messengers.
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## Used libraries
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- [Signal Protocol (android)](https://github.com/signalapp/libsignal)
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- [Jackson](https://github.com/FasterXML/jackson)
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- [Protobuf (lite)](https://github.com/protocolbuffers/protobuf/tree/main/java)
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- [JUnit4](https://github.com/junit-team/junit4)
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## Credits
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- [AOSP Keyboard](https://android.googlesource.com/platform/packages/inputmethods/LatinIME/)
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- [Simple Keyboard](https://github.com/rkkr/simple-keyboard)
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- [OpenBoard](https://github.com/openboard-team/openboard)
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- [FlorisBoard](https://github.com/florisboard/florisboard)
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