Xx messenger

Privacy-focused encrypted messaging app

xx messenger

Other names| elixxir, PrivaTegrity
Developer(s)|

* David Chaum & partners

Initial release| 25 January 2022; 3 years ago (2022-01-25)
Repository| https://git.xx.network/elixxir
Operating system|

* Android 8 or later
* iOS 14 or later

Type| Encrypted instant messaging
License|

* Client: Simplified BSD License
* Server: Business Source License (BSL)

Website| https://xxfoundation.org/messenger/

xx messenger is a cross-platform decentralized encrypted instant messaging service developed by David Chaum and partners and running on a blockchain called xx network. Messages are delivered over a variety of mix network first described in 2016.[1][2] Users can send one-to-one and group messages, which can include voice notes and images.[3]

xx messenger uses usernames as identifiers which can be optionally attached to standard cellular telephone numbers or email addresses for contact discovery. All communications between users are secured with quantum-resistant end-to-end encryption.[4]

xx messenger's software is free and open-source. Its mobile clients are published under the 2-clause BSD License,[5][6] while its server software is published under a modified, patent-protected Business Source License.[7]

## History

[edit]

An alpha version of xx messenger was first presented on January 6, 2016 by David Chaum at the Real World Crypto conference with the stated goal of demonstrating a new type of mix network encryption scheme.[1] The encryption scheme, known as PrivaTegrity, was described by Chaum and team of academic partners at Purdue University, Radboud University Nijmegen, University of Birmingham, and other schools.[8]

xx messenger was released to the public as a mobile app on Android and IOS on 25 January 2022.[9]

## Architecture

[edit]

### cMix

[edit]

xx messenger uses cMix - a network of decentralized servers called xx network that are run by independent operators in approximately 80 countries - for data transmission.[9] cMix attempts to address traditional latency and scalability limitations of mix networks by performing computationally expensive public-key operations between mix nodes prior to any client data being transmitted over the network. Messages sent by users of xx messenger are grouped in batches of 1,000 and routed through a subset of cMix nodes. Once the mixing process is complete, each message can be retrieved and decrypted by their recipient.[8]

### Encryption protocols

[edit]

The cMix protocol uses XChaCha20, BLAKE2b, HMAC-SHA-256, Diffie–Hellman key exchange, and Supersingular isogeny key exchange as cryptographic primitives.[10] Messages are encrypted in two layers. The inner layer is encrypted with ChaCha20 symmetric encryption. This payload is then encrypted once more for transmission over the mixnet using multi-party ElGamal encryption. The encryption protocols, in addition to the properties provided by the mixnet, allow both anonymity preservation and traditional end-to-end security guarantees, as well as preliminary post-quantum security with a traditional fallback mechanism.[11]

## See also

[edit]

* Freedom of speech portal
* Free and open-source software portal
* Telecommunications portal

* Comparison of cross-platform instant messaging clients
* Internet privacy
* Secure communication

## References

[edit]

1. ^ a b Greenberg, Andy (6 January 2016). "The Father of Online Anonymity Has a Plan to End the Crypto War". Wired. ISSN 1059-1028. Archived from the original on 10 January 2016. Retrieved 2022-08-30.
2. ^ "Program". rwc.iacr.org. The International Association for Cryptologic Research. Archived from the original on 31 May 2025. Retrieved 31 May 2025. "Session 4: Mixing and voting (session chair: Aggelos Kiayias) 2:00pm PrivaTegrity:online communication with strong privacy David Chaum 2:30pm"
3. ^ "Private Messaging App Launches on Quantum Resistant, Decentralized xx network". www.businesswire.com. 2022-01-25. Retrieved 2022-08-30.
4. ^ Quantent (April 1, 2022). "Is the XX messenger the future of private communication?". CNBC. Retrieved August 29, 2022.
5. ^ "LICENSE · main · elixxir / xx messenger iOS · GitLab". GitLab. 15 February 2022. Retrieved 2022-08-30.
6. ^ "LICENSE · master · elixxir / xx Messenger Android · GitLab". GitLab. 15 February 2022. Retrieved 2022-08-30.
7. ^ "LICENSE · release · elixxir / server · GitLab". GitLab. 30 August 2022. Retrieved 2022-08-30.
8. ^ a b Chaum, David, et al. "cMix: Anonymization by high-performance scalable mixing." USENIX Security. 2016.
9. ^ a b Lüthje, Simon (2022-01-26). "xx messenger: New private messaging app launches on decentralized network". Basic Tutorials. Retrieved 2022-08-30.
10. ^ Team, xx network. "Tech Specs". elixxir. Retrieved 2022-08-30.
11. ^ Chaum, D., Das, D., Javani, F., Kate, A., Krasnova, A., Ruiter, J.D., & Sherman, A.T. (2017). cMix: Mixing with Minimal Real-Time Asymmetric Cryptographic Operations. ACNS.

* v
* t
* e

Cryptographic software

Email clients|

* Apple Mail
* Autocrypt
* Claws Mail
* Enigmail
* GPG
* Gpg4win
* GPG Mail
* Kontact
* Outlook
* p≡p
* PGP
* Sylpheed
* Thunderbird

Secure
communication|

| OTR|

* Adium
* BitlBee
* Centericq
* ChatSecure
* climm
* Jitsi
* Kopete
* Profanity

|

SSH|

* Dropbear
* lsh
* OpenSSH
* PuTTY
* SecureCRT
* WinSCP
* wolfSSH

TLS & SSL|

* BBM Enterprise
* Bouncy Castle
* BoringSSL
* Botan
* cryptlib
* GnuTLS
* JSSE
* LibreSSL
* MatrixSSL
* NSS
* OpenSSL
* mbed TLS
* BSAFE
* SChannel
* SSLeay
* stunnel
* TeamNote
* wolfSSL

VPN|

* Check Point VPN-1
* Hamachi
* Openswan
* OpenVPN
* SoftEther VPN
* strongSwan
* Tinc
* WireGuard

ZRTP|

* Jitsi
* Linphone
* Jami
* Zfone

P2P|

* Bitmessage
* Briar
* RetroShare
* Tox

DRA|

* Matrix
* OMEMO
* Cryptocat
* ChatSecure
* Proteus
* Session
* Signal Protocol
* Facebook Messenger
* Google Allo
* Google Messages
* Signal
* TextSecure
* WhatsApp

Disk encryption
(Comparison)|

* BestCrypt
* BitLocker
* Cryptoloop
* dm-crypt
* DriveSentry
* E4M
* eCryptfs
* FileVault
* FreeOTFE
* GBDE
* geli
* LUKS
* PGPDisk
* Private Disk
* Scramdisk
* Sentry 2020
* TrueCrypt
* History
* VeraCrypt

Anonymity|

* GNUnet
* I2P
* Java Anon Proxy
* Tor
* Vidalia
* RetroShare
* Ricochet
* Wickr

File systems (List)|

* EncFS
* EFS
* eCryptfs
* LUKS
* PEFS
* Rubberhose
* StegFS
* Tahoe-LAFS

Security-focused
operating system|

* Tails
* Qubes

Service providers|

* Hyphanet
* Tresorit
* Wuala
* NordLocker

Educational|

* CrypTool

Anti–computer forensics|

* USBKill
* BusKill

Related topics|

* Outline of cryptography
* Timeline of cryptography
* Hash functions
* Cryptographic hash function
* List of hash functions
* Homomorphic encryption
* End-to-end encryption
* S/MIME

* Category
* Commons

* v
* t
* e

Instant messaging

Protocols
(comparison)|

| Open|

* DDP
* IMPP
* IRC
* Matrix
* MTProto
* Retroshare
* Signal Protocol
* SIP
* MSRP
* SIMPLE
* Tox
* XMPP
* Jingle
* WFP
* Zephyr

|

Closed|

* MSNP
* OSCAR
* TOC
* Skype

Services|

* Band
* BBM Enterprise
* Beeper
* BiP
* DingTalk
* Discord
* Element
* Google Chat
* Google Meet
* Google Messages
* GroupMe
* Guilded
* iGap
* iMessage
* Imo
* Instagram Direct Messenger
* JioChat
* Jongla
* KakaoTalk
* Kik
* Lark
* Libon
* Line
* Marco Polo
* Mattermost
* Facebook Messenger
* Messenger Kids
* The Palace
* QQ
* Sandes
* Session
* ShareChat
* Signal
* Slack
* Snapchat
* Snow
* Tango Live
* Telegram
* Textfree
* Threema
* Trillian
* Viber
* VK Messenger
* WeChat
* WhatsApp
* Wickr
* WOLF
* Zoom
* Zulip

Clients
(comparison)|

| Single protocol|

* Baidu Hi
* BBM Enterprise
* Briar
* Element
* FaceTime
* Gadu-Gadu
* GroupMe
* HCL Sametime
* IMVU
* Jami
* Jongla
* Linphone
* Facebook Messenger
* QQ
* Retroshare
* Ricochet
* Session
* Signal
* Telegram
* Tox
* WeChat
* WhatsApp
* Wickr
* Wire
* WOLF

|

Multi-protocol|

* Adium
* Ayttm
* Beeper
* BitlBee
* Centericq
* eBuddy
* Jitsi
* Kopete
* Messages
* Miranda NG
* Nimbuzz
* Pidgin
* Finch
* Telepathy
* Thunderbird
* Trillian

XMPP (Jabber)|

* ChatSecure
* Conversations
* Gajim
* Psi
* Spark
* Tkabber
* Xabber

MSNP|

* Microsoft Teams

Defunct|

* List of defunct instant messaging platforms

Related|

* Backchannel
* Chat log
* Chatbot
* Circuit
* Comparison of user features of messaging platforms
* Contact list
* Emoticon
* File sharing
* FirstClass
* Flock
* Fuze Box
* Hall.com
* LAN messenger
* Online chat
* Presence information
* RingCentral Glip
* SMS language
* Status message
* U-Report
* Videotelephony
* Viva Engage
* VoIP
* Webcam

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