macOS
Homebrewverified · 100%
brew install libotrlocal Homebrew formula metadata
MacPortsverified · 94%
sudo port install libotrMacPorts ports tree · security/libotr/Portfile · source: api.github.com
brew
Install libotr with Homebrew, apk, apt, dnf, MacPorts, Nix, pacman, zypper
Off-The-Record (OTR) messaging library. Version 4.1.1 via Homebrew; verified 2026-06-19.
install
Additional install commands
Linux
Alpine Linux apkverified · 92%
sudo apk add libotrAlpine Linux edge package indexes · libotr · source: dl-cdn.alpinelinux.org
Debian aptverified · 92%
sudo apt install libotr5-binDebian stable package indexes · libotr5-bin · source: deb.debian.org
Fedora dnfverified · 92%
sudo dnf install libotrFedora Rawhide package metadata · libotr · source: dl.fedoraproject.org
Nixverified · 92%
nix profile install nixpkgs#libotrnixpkgs package indexes · pkgs/by-name/li/libotr/package.nix · source: api.github.com
Arch Linux pacmanverified · 92%
sudo pacman -S libotrArch Linux sync databases · libotr · source: geo.mirror.pkgbuild.com
openSUSE zypperverified · 92%
sudo zypper install libotr-developenSUSE Tumbleweed package metadata · libotr-devel · source: download.opensuse.org
overview
Package summary
Off-The-Record (OTR) messaging library
Project links
Commands and aliases
- otr_mackey
- otr_modify
- otr_parse
- otr_readforge
- otr_remac
- otr_sesskeys
history
Project history and usage
libotr is the portable C library and toolkit for Off-the-Record Messaging, a protocol for private instant-messaging conversations with encryption, authentication during the conversation, deniability after the fact, and perfect forward secrecy.
Project history
OTR came from academic and cypherpunk work on making instant messaging behave more like an off-the-record conversation than signed email. The official OTR site links the library, the Pidgin plugin, protocol descriptions, and the original research papers as one software-and-protocol family.
libotr served as the reference C implementation for client developers. The project paired the LGPL library with GPL toolkit programs and with pidgin-otr, making it practical for multiprotocol IM clients to add OTR without each client reimplementing the cryptographic state machine.
Adoption history
OTR became especially associated with desktop XMPP and multiprotocol IM clients. XMPP Extension Protocol 0364 described OTR as the de facto standard for end-to-end encryption in XMPP, while the OTR site maintained user-facing downloads for pidgin-otr, source repositories, protocol documents, and implementation lists.
How it is used
Applications link libotr to negotiate OTR sessions, run the authenticated key exchange, encrypt and authenticate data messages, and expose higher-level verification flows such as the Socialist Millionaires' Protocol. The Homebrew package also installs toolkit programs for inspecting, modifying, and testing OTR message artifacts.
Why package nerds care
libotr matters because it is a small library package carrying a big protocol story: it let package managers deliver interoperable deniable encryption to chat clients before modern app-specific encrypted messengers became dominant. Its 2016 security release also shows why distro maintainers cared about keeping even niche crypto libraries patched.
Timeline
- 2004: The OTR design was published in the WPES paper linked from the official OTR documentation.
- 2012: libotr 4.0.0 and pidgin-otr 4.0.0 were released.
- 2014: libotr 4.1.0 was released with build-system, secure-memory, constant-time comparison, and API changes.
- 2016: libotr 4.1.1 fixed CVE-2016-2851 and tightened protocol parsing.
Related projects
- pidgin-otr is the best-known client plugin distributed alongside libotr by the OTR project.
- The OTR protocol documents define the wire protocol that libotr implements.
- XMPP clients and multiprotocol IM clients were the main ecosystem where libotr was reused.
Sources
security posture
Risk level: green
library-like package without higher-risk signals.
Risk classifier
green risk · low confidence · appliance
Why
- library-like package without higher-risk signals
Signals
- metadata:library-like
Install behavior
- No Homebrew post-install hook is recorded in formula metadata.
- Homebrew bottle metadata is available for 13 platform targets.
- Installs with 2 runtime dependencies.
Recommended review
Before unattended agent use, check whether the tool reads plaintext credentials, writes remote state, publishes artifacts, or shells out to plugins.
executables
Installed executables
| Command | Kind | Exposure | Note |
|---|---|---|---|
otr_mackey | cli | global executable | |
otr_modify | cli | global executable | |
otr_parse | cli | global executable | |
otr_readforge | cli | global executable | |
otr_remac | cli | global executable | |
otr_sesskeys | cli | global executable |
freshness
Version and freshness
These signals separate page generation age, package-manager activity, and upstream release comparison. Version lag is warned only when an evidence URL and comparable versions are present.
page generated2026-07-08
manager version4.1.1
manager updated2026-06-19
local dataok
upstreamnot checked
latest detectednot detected
- infoRelease/tag comparison is only available for GitHub repositories.https://otr.cypherpunks.ca/none confidence
install metadata
Package metadata
| Package key | brew:libotr |
|---|---|
| Version | 4.1.1 |
| Package manager | Homebrew |
| Package manager page | https://formulae.brew.sh/formula/libotr |
| Homepage | https://otr.cypherpunks.ca/ |
| Repository | https://bugs.otr.im/git/libotr.git |
| Upstream docs | https://otr.cypherpunks.ca/ |
| License | LGPL-2.1-only AND GPL-2.0-only |
| Source archive | https://otr.cypherpunks.ca/libotr-4.1.1.tar.gz |
| Last updated | 2026-06-19T12:32:38-07:00 |
| Pulse | updated |
| Dependencies | libgcrypt, libgpg-error |
| Bottle | available (on arm64_big_sur, arm64_linux, arm64_monterey, arm64_sequoia, arm64_sonoma, arm64_tahoe, arm64_ventura, big_sur, catalina, monterey, sonoma, ventura, x86_64_linux) |
| Homebrew post-install | not defined |
| Service | none declared |
registry facts
Source database details
| Source Database | Homebrew formula API |
|---|---|
| Tap | homebrew/core |
| Full Name | libotr |
| Version Scheme | 0 |
| Revision | 0 |
| Bottle Stable Root URL | https://ghcr.io/v2/homebrew/core |
| Deprecated | no |
| Disabled | no |
| Keg Only | no |
| URL Keys |
|
source database matches
Other package-manager records
Matches are pulled from external package-manager indexes and kept separate from local Automic Vault package links.
Debian apt95%
libotr5-bin 4.1.1-6
toolkit for Off-the-Record Messaging library
sudo apt install libotr5-bin- Section: misc
- Architecture: amd64
- Source Package: libotr
- 3 dependencies
- normalized package name match
- Matched by: Libotr
Debian apt95%
libotr5-dev 4.1.1-6
Off-the-Record Messaging library development files
sudo apt install libotr5-dev- Section: libdevel
- Architecture: amd64
- Source Package: libotr
- 2 dependencies
- 1 optional deps
- normalized package name match
- Matched by: Libotr
Debian apt95%
libotr5t64 4.1.1-6
Off-the-Record Messaging library
sudo apt install libotr5t64- Section: libs
- Architecture: amd64
- Source Package: libotr
- 2 dependencies
- 1 provides
- 1 optional deps
- normalized package name match
- Matched by: Libotr
Nix95%
libotr
nix profile install nixpkgs#libotr- normalized package name match
- Matched by: Libotr
Ubuntu apt95%
libotr5-bin 4.1.1-5.1build1
toolkit for Off-the-Record Messaging library
sudo apt install libotr5-bin- Section: universe/misc
- Architecture: amd64
- Source Package: libotr
- 3 dependencies
- normalized package name match
- Matched by: Libotr
Ubuntu apt95%
libotr5-dev 4.1.1-5.1build1
Off-the-Record Messaging library development files
sudo apt install libotr5-dev- Section: universe/libdevel
- Architecture: amd64
- Source Package: libotr
- 2 dependencies
- 1 optional deps
- normalized package name match
- Matched by: Libotr
Ubuntu apt95%
libotr5t64 4.1.1-5.1build1
Off-the-Record Messaging library
sudo apt install libotr5t64- Section: universe/libs
- Architecture: amd64
- Source Package: libotr
- 2 dependencies
- 1 provides
- 1 optional deps
- normalized package name match
- Matched by: Libotr
apk95%
libotr 4.1.1-r5
Off The Record Messaging, an encryption library for secure IM conversations
sudo apk add libotr- License: LGPL-2.1-only
- Architecture: x86_64
- Source Package: libotr
- 1 dependencies
- 1 provides
- normalized package name match
- Matched by: Libotr
apk95%
libotr-dev 4.1.1-r5
Off The Record Messaging, an encryption library for secure IM conversations (development files)
sudo apk add libotr-dev- License: LGPL-2.1-only
- Architecture: x86_64
- Source Package: libotr
- 1 dependencies
- 1 provides
- normalized package name match
- Matched by: Libotr
apk95%
libotr-doc 4.1.1-r5
Off The Record Messaging, an encryption library for secure IM conversations (documentation)
sudo apk add libotr-doc- License: LGPL-2.1-only
- Architecture: x86_64
- Source Package: libotr
- normalized package name match
- Matched by: Libotr
apk95%
libotr-tools 4.1.1-r5
libotr tools
sudo apk add libotr-tools- License: LGPL-2.1-only
- Architecture: x86_64
- Source Package: libotr
- 1 dependencies
- 1 provides
- normalized package name match
- Matched by: Libotr
dnf95%
libotr 4.1.1-25.fc44
Off-The-Record Messaging library and toolkit
sudo dnf install libotr- License: GPL-2.0-only AND LicenseRef-Callaway-LGPLv2
- Category: Unspecified
- Architecture: i686
- Source Package: libotr
- 6 dependencies
- 3 provides
- normalized package name match
- Matched by: Libotr
dnf95%
libotr-devel 4.1.1-25.fc44
Development library and include files for libotr
sudo dnf install libotr-devel- License: GPL-2.0-only AND LicenseRef-Callaway-LGPLv2
- Category: Unspecified
- Architecture: i686
- Source Package: libotr
- 4 dependencies
- 2 provides
- normalized package name match
- Matched by: Libotr
pacman95%
libotr 4.1.1-6
Off-the-Record Messaging Library and Toolkit
sudo pacman -S libotr- License: GPL-2.0-only AND LGPL-2.1-only
- Architecture: x86_64
- 2 dependencies
- normalized package name match
- Matched by: Libotr
zypper95%
libotr-devel 4.1.1-4.12
Include files and development libraries
https://www.cypherpunks.ca/otr/
sudo zypper install libotr-devel- License: GPL-2.0-only AND LGPL-2.1-only
- Category: Development/Libraries/C and C++
- Architecture: x86_64
- Source Package: libotr
- 3 dependencies
- 2 provides
- normalized package name match
- Matched by: Libotr
zypper95%
libotr-tools 4.1.1-4.12
"Off The Record" messaging library toolkit
https://www.cypherpunks.ca/otr/
sudo zypper install libotr-tools- License: GPL-2.0-only
- Category: Development/Libraries/C and C++
- Architecture: x86_64
- Source Package: libotr
- 3 dependencies
- 1 provides
- normalized package name match
- Matched by: Libotr
source trail
Generated from repository data
This page is generated by av-web from the private package SQLite artifact built by scripts/generate-pkg-sqlite.py.
Combined YAML source
View the package source record on GitHub.
Used sources
- Geiger risk classifier
- Nucleus package database
- av.db category and tag curation
- cross-ecosystem install command graph
- curated package history
- external package-manager database matches
- package relationship graph
- package version freshness
- package-page enrichment