# 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 ```sh sudo av install brew:libotr ``` Additional install commands: ### macOS - Homebrew (100%): ```sh brew install libotr ``` Evidence: local Homebrew formula metadata - MacPorts (94%): ```sh sudo port install libotr ``` Evidence: MacPorts ports tree: security/libotr/Portfile from https://api.github.com/repos/macports/macports-ports/git/trees/master?recursive=1 ### Linux - apk (92%): ```sh sudo apk add libotr ``` Evidence: Alpine Linux edge package indexes: libotr from https://dl-cdn.alpinelinux.org/alpine/edge/main/x86_64/APKINDEX.tar.gz - Debian apt (92%): ```sh sudo apt install libotr5-bin ``` Evidence: Debian stable package indexes: libotr5-bin from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz - dnf (92%): ```sh sudo dnf install libotr ``` Evidence: Fedora Rawhide package metadata: libotr from https://dl.fedoraproject.org/pub/fedora/linux/development/rawhide/Everything/x86_64/os/repodata/e5ca8ce900cd68f5419e1c39ae517343100b306336cbaeb70a3c153121d95094-primary.xml.zst - Nix (92%): ```sh nix profile install nixpkgs#libotr ``` Evidence: nixpkgs package indexes: pkgs/by-name/li/libotr/package.nix from https://api.github.com/repos/NixOS/nixpkgs/git/trees/master?recursive=1 - pacman (92%): ```sh sudo pacman -S libotr ``` Evidence: Arch Linux sync databases: libotr from https://geo.mirror.pkgbuild.com/extra/os/x86_64/extra.db.tar.gz - zypper (92%): ```sh sudo zypper install libotr-devel ``` Evidence: openSUSE Tumbleweed package metadata: libotr-devel from https://download.opensuse.org/tumbleweed/repo/oss/repodata/be8d3611d25469107f32075a1697e69ec57a2b850b42348a658cc671ad5ec2b50760d02c3e59524d50da9a11d5be799bdaffba2e166e8ca8858512e3c0bd665d-primary.xml.zst ## Package facts - **Package key:** brew:libotr - **Package manager:** Homebrew - **Package manager page:** - **Version:** 4.1.1 - **Source summary:** Off-The-Record (OTR) messaging library - **Homepage:** - **Repository:** - **Upstream docs:** - **License:** LGPL-2.1-only AND GPL-2.0-only - **Source archive:** - **Last updated:** 2026-06-19T12:32:38-07:00 - **Generated:** 2026-07-08T07:18:31+00:00 ## Executables - otr_mackey (cli) - otr_modify (cli) - otr_parse (cli) - otr_readforge (cli) - otr_remac (cli) - otr_sesskeys (cli) - otr_mackey (alias) - otr_modify (alias) - otr_parse (alias) - otr_readforge (alias) - otr_remac (alias) - otr_sesskeys (alias) ## Dependencies - libgcrypt - libgpg-error ## Install behavior - Post-install hook: not defined - Bottle: available on arm64_big_sur, arm64_linux, arm64_monterey, arm64_sequoia, arm64_sonoma, arm64_tahoe, arm64_ventura, big_sur, catalina, monterey, sonoma, ventura ## Freshness - Page generated: 2026-07-08 - Package-manager version: 4.1.1 - Package-manager updated: 2026-06-19 - Local data: ok - Upstream repository: https://otr.cypherpunks.ca/ - info: Release/tag comparison is only available for GitHub repositories. ## 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 Notes library-like package without higher-risk signals. - **Geiger risk:** green / low - library-like package without higher-risk signals ## Source Database Details - **Source Database:** Homebrew formula API - **Tap:** homebrew/core - **Full Name:** libotr - **Version Scheme:** 0 - **Revision:** 0 - **Bottle Stable Root URL:** - **Deprecated:** no - **Disabled:** no - **Keg Only:** no - **URL Keys:** stable ## Other Package-Manager Records - Debian apt - libotr5-bin - 4.1.1-6: normalized package name match | Debian stable package indexes: libotr5-bin from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz | toolkit for Off-the-Record Messaging library | https://otr.cypherpunks.ca/ - Debian apt - libotr5-dev - 4.1.1-6: normalized package name match | Debian stable package indexes: libotr5-dev from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz | Off-the-Record Messaging library development files | https://otr.cypherpunks.ca/ - Debian apt - libotr5t64 - 4.1.1-6: normalized package name match | Debian stable package indexes: libotr5t64 from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz | Off-the-Record Messaging library | https://otr.cypherpunks.ca/ - Nix - libotr: normalized package name match | nixpkgs package indexes: pkgs/by-name/li/libotr/package.nix from https://api.github.com/repos/NixOS/nixpkgs/git/trees/master?recursive=1 - Ubuntu apt - libotr5-bin - 4.1.1-5.1build1: normalized package name match | Ubuntu 24.04 LTS package indexes: libotr5-bin from https://archive.ubuntu.com/ubuntu/dists/noble/universe/binary-amd64/Packages.gz | toolkit for Off-the-Record Messaging library | https://otr.cypherpunks.ca/ - Ubuntu apt - libotr5-dev - 4.1.1-5.1build1: normalized package name match | Ubuntu 24.04 LTS package indexes: libotr5-dev from https://archive.ubuntu.com/ubuntu/dists/noble/universe/binary-amd64/Packages.gz | Off-the-Record Messaging library development files | https://otr.cypherpunks.ca/ - Ubuntu apt - libotr5t64 - 4.1.1-5.1build1: normalized package name match | Ubuntu 24.04 LTS package indexes: libotr5t64 from https://archive.ubuntu.com/ubuntu/dists/noble/universe/binary-amd64/Packages.gz | Off-the-Record Messaging library | https://otr.cypherpunks.ca/ - apk - libotr - 4.1.1-r5: normalized package name match | Alpine Linux edge package indexes: libotr from https://dl-cdn.alpinelinux.org/alpine/edge/main/x86_64/APKINDEX.tar.gz | Off The Record Messaging, an encryption library for secure IM conversations | http://otr.cypherpunks.ca/ - apk - libotr-dev - 4.1.1-r5: normalized package name match | Alpine Linux edge package indexes: libotr-dev from https://dl-cdn.alpinelinux.org/alpine/edge/main/x86_64/APKINDEX.tar.gz | Off The Record Messaging, an encryption library for secure IM conversations (development files) | http://otr.cypherpunks.ca/ - apk - libotr-doc - 4.1.1-r5: normalized package name match | Alpine Linux edge package indexes: libotr-doc from https://dl-cdn.alpinelinux.org/alpine/edge/main/x86_64/APKINDEX.tar.gz | Off The Record Messaging, an encryption library for secure IM conversations (documentation) | http://otr.cypherpunks.ca/ - apk - libotr-tools - 4.1.1-r5: normalized package name match | Alpine Linux edge package indexes: libotr-tools from https://dl-cdn.alpinelinux.org/alpine/edge/main/x86_64/APKINDEX.tar.gz | libotr tools | http://otr.cypherpunks.ca/ - dnf - libotr - 4.1.1-25.fc44: normalized package name match | Fedora Rawhide package metadata: libotr from https://dl.fedoraproject.org/pub/fedora/linux/development/rawhide/Everything/x86_64/os/repodata/e5ca8ce900cd68f5419e1c39ae517343100b306336cbaeb70a3c153121d95094-primary.xml.zst | Off-The-Record Messaging library and toolkit | http://otr.cypherpunks.ca/ - dnf - libotr-devel - 4.1.1-25.fc44: normalized package name match | Fedora Rawhide package metadata: libotr-devel from https://dl.fedoraproject.org/pub/fedora/linux/development/rawhide/Everything/x86_64/os/repodata/e5ca8ce900cd68f5419e1c39ae517343100b306336cbaeb70a3c153121d95094-primary.xml.zst | Development library and include files for libotr | http://otr.cypherpunks.ca/ - pacman - libotr - 4.1.1-6: normalized package name match | Arch Linux sync databases: libotr from https://geo.mirror.pkgbuild.com/extra/os/x86_64/extra.db.tar.gz | Off-the-Record Messaging Library and Toolkit | https://otr.cypherpunks.ca/ - zypper - libotr-devel - 4.1.1-4.12: normalized package name match | openSUSE Tumbleweed package metadata: libotr-devel from https://download.opensuse.org/tumbleweed/repo/oss/repodata/be8d3611d25469107f32075a1697e69ec57a2b850b42348a658cc671ad5ec2b50760d02c3e59524d50da9a11d5be799bdaffba2e166e8ca8858512e3c0bd665d-primary.xml.zst | Include files and development libraries | https://www.cypherpunks.ca/otr/ - zypper - libotr-tools - 4.1.1-4.12: normalized package name match | openSUSE Tumbleweed package metadata: libotr-tools from https://download.opensuse.org/tumbleweed/repo/oss/repodata/be8d3611d25469107f32075a1697e69ec57a2b850b42348a658cc671ad5ec2b50760d02c3e59524d50da9a11d5be799bdaffba2e166e8ca8858512e3c0bd665d-primary.xml.zst | "Off The Record" messaging library toolkit | https://www.cypherpunks.ca/otr/ ## Related links - [Terminal utility packages](https://www.automicvault.com/pkg/terminal-utilities/) - Matched terminal and command-line workflow metadata. - [Networking and protocol packages](https://www.automicvault.com/pkg/networking-protocol-tools/) - Matched network, protocol, or remote-service metadata. - [Security and crypto packages](https://www.automicvault.com/pkg/security-crypto-tools/) - Matched security, identity, cryptography, password, signing, or certificate metadata. - [Homebrew utility packages](https://www.automicvault.com/pkg/brew-utility-packages/) - Matched Homebrew package provider. - [libgcrypt](https://www.automicvault.com/pkg/brew/libgcrypt/) - Runtime dependency declared by Homebrew. - [libgpg-error](https://www.automicvault.com/pkg/brew/libgpg-error/) - Runtime dependency declared by Homebrew. - [mcabber](https://www.automicvault.com/pkg/brew/mcabber/) - Popular package that depends on this formula. - [pidgin](https://www.automicvault.com/pkg/brew/pidgin/) - Popular package that depends on this formula. - [profanity](https://www.automicvault.com/pkg/brew/profanity/) - Popular package that depends on this formula. - [hblock](https://www.automicvault.com/pkg/brew/hblock/) - Shares av.db curated category or tags: cli, privacy, security. - [mat2](https://www.automicvault.com/pkg/brew/mat2/) - Shares av.db curated category or tags: cli, privacy, security. - [botan](https://www.automicvault.com/pkg/brew/botan/) - Shares av.db curated category or tags: cli, cryptography, security. - [gnutls](https://www.automicvault.com/pkg/brew/gnutls/) - Shares av.db curated category or tags: cli, cryptography, security. - [haiti](https://www.automicvault.com/pkg/brew/haiti/) - Shares av.db curated category or tags: cli, cryptography, security. - [nettle](https://www.automicvault.com/pkg/brew/nettle/) - Shares av.db curated category or tags: cli, cryptography, security. - [nss](https://www.automicvault.com/pkg/brew/nss/) - Shares av.db curated category or tags: cli, cryptography, security. - [opensc](https://www.automicvault.com/pkg/brew/opensc/) - Shares av.db curated category or tags: cli, cryptography, security. - [gnupg](https://www.automicvault.com/pkg/brew/gnupg/) - Security-sensitive metadata or terminology overlaps. Shared terms: cli, cryptography, error, libgcrypt, libgpg. - [gnupg-pkcs11-scd](https://www.automicvault.com/pkg/brew/gnupg-pkcs11-scd/) - Security-sensitive metadata or terminology overlaps. Shared terms: cli, cryptography, error, libgcrypt, libgpg. - [aide](https://www.automicvault.com/pkg/brew/aide/) - Security-sensitive metadata or terminology overlaps. Shared terms: cli, error, libgcrypt, libgpg, libgpg-error. ## Combined YAML source View the package source record on GitHub. [combined/libotr.yml](https://github.com/automic-vault/db/blob/main/combined/libotr.yml) ## Sources - Nucleus package database - Geiger risk classifier - package-page enrichment - curated package history - package version freshness - av.db category and tag curation - package relationship graph - external package-manager database matches - cross-ecosystem install command graph