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Leverage our long-term expertise on secure user authentication and end-to-end encryption.

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Linphone and its components are divers of innovation in many sectors. Read our white papers.

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Linphone

An open source SIP phone for voice/video calls and instant messaging (mobile and desktop)

Liblinphone

A high-level VoIP library implementing all SIP calling and IM features within a single API

Flexisip

A SIP server implementation with proxy, presence and conference modules

Flexisip account manager

A web API, provisioning server and admin platform for the creation and management of user accounts

LIME

End-to-end encryption module for instant messaging, implementing the Signal Protocol

Post quantum encryption

A Linphone extension providing Post Quantum Cryptography (using the Crystals-KYBER algorithm)

Mediastreamer2 & oRTP

A powerful voice/video streaming engine for telephony apps & a C library implementing RTT Protocol

VoIP tunnel

A VoIP anti-blocking solution to overcome VoIP blocking and firewall restrictions

bcg729

A fully portable C99 implementation of both an encoder and decoder for the G.729 A/B codec

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Linphone

An open source SIP phone for voice/video calls and instant messaging (mobile and desktop)

Liblinphone

A high-level VoIP library implementing all SIP calling and IM features within a single API

Flexisip

A SIP server implementation with proxy, presence and conference modules

Flexisip account manager

A web API, provisioning server and admin platform for the creation and management of user accounts

LIME

End-to-end encryption module for instant messaging, implementing the Signal Protocol

Post quantum encryption

A Linphone extension providing Post Quantum Cryptography (using the Crystals-KYBER algorithm)

Mediastreamer2 & oRTP

A powerful voice/video streaming engine for telephony apps & a C library implementing RTT Protocol

VoIP tunnel

A VoIP anti-blocking solution to overcome VoIP blocking and firewall restrictions

bcg729

A fully portable C99 implementation of both an encoder and decoder for the G.729 A/B codec

Menu Solutions

Secure communications

Leverage our long-term expertise on secure user authentication and end-to-end encryption.

All use cases

Linphone and its components are divers of innovation in many sectors. Read our white papers.

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  • Products
  • Solutions
  • Licensing & services
  • Technical corner
  • About us
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En tête technical corner

LIME

Technical corner

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  • Features
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  • Documentation

Description

LIME is an encryption library for one-to-one and group instant messaging, allowing users to exchange messages privately and asynchronously. It supports multiple devices per user and multiple users per device.
It is available as a Liblinphone extension or as a standalone library.

LIME offers two major security benefits to instant messaging users: 

  • end-to-end encryption, which means that only you and your contact (and not even the server) can decrypt the content that you shared
  • perfect forward secrecy, which ensures that encrypted messages cannot by decrypted by a third party, even if a key is compromised in the future

LIME is composed of a portable client library coupled with a public key server developed by Belledonne Communications to allow end-to-end encryption for messaging, without having to exchange cryptographic keys simultaneously.

LIME’s unique features are to support multiple devices per user and the use of the advanced cryptographic curve x448. 

Main features

  • end-to-end encryption based on modern Elliptic Curve Diffie-Hellman(ECDH)
  • perfect forward secrecy with double ratchet algorithm
  • designed for group communications
  • asynchronous messaging system based on pre-positioned keys
  • man-in-the-middle (MITM) detection based on ZRTP auxiliary secret
  • signaling protocol agnostic

LIME library and LIME server

LIME library is a portable, signaling-independent component designed for sharing end-to-end ciphered text and documents. LIME is not linked to any signaling protocol and can be used with SIP alternatives like XMPP or any proprietary protocol with unique device identifier support.

LIME exposes a C, C++, Python and Java API for easy integration in mobile and desktop environments. Message overhead is limited thanks to the efficiency of X25519 or X448 Elliptic Curves Diffie-Hellman. LIME allows key agreements to be done asynchronously using pre-positioned public keys published to the LIME server over a secured https link.

License

LIME library is dual licensed, and can be licensed and distributed:

  • under a GNU/GPLv3 license for free (open source)
  • under a proprietary license, to be used in closed source applications. LIME is not included in the proprietary license for Linphone or Liblinphone, it shall be purchased separately.

LIME server is only distributed under a proprietary license (closed source).

Contact Belledonne Communications for costs and other service information.

Source code

The source code of LIME library is available from our GitLab, or can be cloned with Git:

 

Project Git repository
LIME

git clone https://gitlab.linphone.org/BC/public/lime.git

LIME's API reference documentation will soon be generated using Doxygen.

The LIME specification document describes the encryption technologies used in this library.

LIME

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