How was IronChat compromised?


Dutch police have revealed that they were able to spy on the communications of more than 100 suspected criminals, watching live as over a quarter of a million chat messages were exchanged.

The encrypted messages were sent using IronChat, a supposedly secure encrypted messaging service available on BlackBox IronPhones.

IronChat used OTR protocol.


IronChat, based on Xabber (Android)

Signal is also based on OTR protocol. Is Signal compromised also?

In 2013, the Signal Protocol was introduced, which is based on OTR Messaging and the Silent Circle Instant Messaging Protocol (SCIMP).

  • OTR itself is a secure protocol. The issue could only have been an issue with IronChat's implementation or something else specific to that messager.
    – forest
    Commented Nov 15, 2018 at 1:37
  • 1
    Also, the Signal Protocol is not related too closely to OTR nowadays as it has a number of new characteristics not available in OTR (like group chat). Commented Nov 15, 2018 at 1:51
  • @RoboticExtremeties Doesn't Signal use ZRTP, which is totally unrelated to OTR?
    – forest
    Commented Nov 15, 2018 at 2:12
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    @forest I'm not sure but I think that modified ZRTP is used for voice calls and the Signal Protocol for text messaging is only inspired by OTR (see the official docs for a look at the algorithm). Commented Nov 15, 2018 at 2:31
  • Could they have taken over the whole company and pushed special code to interesting parties upon the next app update? Or been allowed into the phone by the phone company or google?
    – dandavis
    Commented Nov 15, 2018 at 6:29

1 Answer 1



There is currently no Public Information how exactly messages were read, but it all points to a faulty Implementation of the Software and bad UI Design.

There was not a Problem with the OTR, there was a Problem with the Implementation of it. On nakedsecurity.sophos.com

For one thing, the app warned users about possible message interception in teensy type, worded in such a way that an average user wouldn’t understand, he said, if they read the smaller font at all. The warning:

Encryption is enabled, but conversation partner is not authenticate

And arstechnica.com

An article published by Dutch public broadcaster NOS said a version of the IronChat app it investigated suffered a variety of potentially serious weaknesses. Key among them: warning messages that notified users when their contacts’ encryption keys had changed were easy to overlook because they were provided in a font much smaller than the rest of the conversation. While crypto keys often change for legitimate reasons, such as when someone obtains a new phone, a new key might also be a sign a third party is trying to intercept the communications by encrypting them with a key it controls.

For Signal in the same news

The Signal app, for instance, encrypts messages using the recipient’s public key before it leaves the sender’s device. As a result, messages that pass through Signal’s central servers can be decrypted only by the recipients’ private key, which is stored only on the recipients’ individual devices. In the event law enforcement took control of the server, they would be unable to read the content of messages without substantially updating the Signal app and waiting for targets to install the update. Even then, they would be able to read only messages sent after the update was installed. Earlier messages would remain unreadable.

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