gnu: Add pidgin-otr.

* gnu/packages/messaging.scm (pidgin-otr): New variable.

gnu/packages/messaging.scm

@@ -319,4 +319,42 @@ chat protocols.")
        "file://libpurple/protocols/zephyr/mit-sipb-copyright.h"
        "See libpurple/protocols/zephyr/mit-sipb-copyright.h in the distribution.")))))
 
+(define-public pidgin-otr
+  (package
+    (name "pidgin-otr")
+    (version "4.0.1")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "https://otr.cypherpunks.ca/"
+                                  name "-" version ".tar.gz"))
+              (sha256
+               (base32
+                "02pkkf86fh5jvzsdn9y78impsgzj1n0p81kc2girvk3vq941yy0v"))))
+    (build-system gnu-build-system)
+    (native-inputs
+     `(("pkg-config" ,pkg-config)
+       ("intltool" ,intltool)))
+    (inputs
+     `(("pidgin" ,pidgin)
+       ("libotr" ,libotr)
+       ("libgpg-error" ,libgpg-error)
+       ("libgcrypt" ,libgcrypt)
+       ("glib" ,glib)
+       ("gtk+" ,gtk+-2)))
+    (home-page "https://otr.cypherpunks.ca/")
+    (synopsis "Off-the-Record Messaging plugin for Pidgin")
+    (description
+     "Pidgin-OTR is a plugin that adds support for OTR to the Pidgin instant
+messaging client.  OTR (Off-the-Record) Messaging allows you to have private
+conversations over instant messaging by providing: (1) Encryption: No one else
+can read your instant messages.  (2) Authentication: You are assured the
+correspondent is who you think it is.  (3) Deniability: The messages you send
+do not have digital signatures that are checkable by a third party.  Anyone
+can forge messages after a conversation to make them look like they came from
+you.  However, during a conversation, your correspondent is assured the
+messages he sees are authentic and unmodified.  (4) Perfect forward secrecy:
+If you lose control of your private keys, no previous conversation is
+compromised.")
+    (license gpl2)))
+
 ;;; messaging.scm ends here