otrv4/libotr-ng-toolkit

OTRv4 toolkit / libotr-ng-toolkit

This is OTRv4 toolkit implementation.

The libotr-n toolkit is useful for analyzing and/or forging OTRv4 messages.

It makes absolutely sure that transcripts of OTRv4 conversations are really easy to forge after the fact to prove offline deniability.

It also makes absolutely sure that OTRv4 conversations can be online deniable by showing how to impersonate or use forging keys.

Easily-forgeable transcripts help us provide the "Deniability" property: if someone claims you said something over OTR, they'll have no proof, as anyone at all can modify a transcript to make it say whatever they like, and still have all the verification come out correctly.

Build

Install the following dependencies:

• libglib2.0-dev
• libgoldilocks
• libsodium-dev
• libotr 4.x
• libotr-ng
• libgcrypt 1.8.0 or newer

To generate project configuration:

$ autoreconf --install

To configure the project:

$ ./configure

To build and install:

$ make && make install

To run the tests:

$ make test

libotr-ng-toolkit's Issues

Implement forge DAKE and session keys (Non-Interactive)

Description:

DAKE and session keys function should be able to forge a DAKE transcript.

If someone wants to forge a DAKE with Bob, this function will need:

For non-interactive:

• Alice's Client Profile
• Alice's long-term secret key
• Bob's Prekey Ensemble

Reference:
https://bugs.otr.im/lib/libotr/blob/master/README (TOOLKIT section)
https://bugs.otr.im/lib/libotr/tree/master/toolkit
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts
https://github.com/otrv4/otrv4/blob/master/otrv4.md#interactive-deniable-authenticated-key-exchange-dake
https://github.com/otrv4/otrv4/blob/master/otrv4.md#non-interactive-deniable-authenticated-key-exchange-dake
https://github.com/otrv4/otrv4/blob/master/otrv4.md#publishing-prekey-ensembles

Implement modify data message

Description:
Modify function should receive the data message and modify the text in it.

For that the user must to give the MAC key for that message (in order to generate a new mac for the modified message).

Reference:
https://bugs.otr.im/lib/libotr/blob/master/README (TOOLKIT section)
https://bugs.otr.im/lib/libotr/tree/master/toolkit
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts
https://en.wikipedia.org/wiki/Malleability_(cryptography)

Adjust functions with Valgrind

Forge with forge key

This functions gets from the client profile the forge keys and use it all over the protocol instead of use the 'real' key of the user.

To do this function is necessary forge keys presence into the client profile

Add impersonate responder function (Interactive)

Description:
The function to impersonate the responder should receive a long-term secret key, and with this should change the responder to use this key (by executing a Rsig)

References:
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts
https://github.com/otrv4/otrv4/blob/master/otrv4.md#ring-signature-authentication

Improve make code-style

Add impersonate responder function (Non-Interactive)

Description:
The function to impersonate the responder should receive a long-term secret key, and with this should change the responder to use this key (by executing a Rsig)

References:
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts
https://github.com/otrv4/otrv4/blob/master/otrv4.md#ring-signature-authentication

Implement change mac of message

Description:
Remac function should receive an encrypted data message and a mac key. With this it has to generate a new mac tag and then replace the original one in the data message and returns a new encrypted data message with this mac tag.

References:
https://bugs.otr.im/lib/libotr/blob/master/README (TOOLKIT section)
https://bugs.otr.im/lib/libotr/tree/master/toolkit
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts (ReMac message section)

Enable debug flag not working

It shows:

configure: WARNING: unrecognized options: --enable-debug

Improve and adjust build configuration and makefiles

Before the work begin is good to:

• Have the build passing and also being well configured to not take longer than it's necessary.
• Check if the makefiles provides all the necessary steps/functions to the toolkit be running smoothly (This include the makefile of the test as well)

Add license and copyright info

This project has no license or copyright info yet.

We can do something similar with what was done at this issue.

False Prekey Ensemble

Description:

This function should return a valid prekey ensemble but differently from the person you want to falsify the prekey ensemble.

If Alice wants to generate a false prekey ensemble for Bob, This function should return a valid prekey ensemble with information her client profile and prekey profile.

Reference:
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts
https://github.com/otrv4/otrv4/blob/master/otrv4.md#publishing-prekey-ensembles
https://github.com/otrv4/otrv4/blob/master/otrv4.md#create-a-prekey-profile-signature

Forge entire transcript (Interactive)

Description:

Forge entire transcript should output a complete transcript of a conversation between the person who is fornging and other person.

For the case of someones who wants to forge a entire transcript with Bob, they will receive:

• Alice's long term secret key
• Alice's Client Profile
• Bob's Client Profile
• The text messages that should be in the transcript

Reference:
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts

Forge entire transcript (Non-interactive)

Description:

Forge entire transcript should output a complete transcript of a conversation between the person who is forging and the other person.

For the case someone wants to forge a entire transcript with Bob, they will receive:

• Alice's long term secret key
• Alice's Client Profile
• Bob's Prekey Ensemble
• The text messages that should be in the transcript

Reference:
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts

Implement parsing

Description:

OTR_parse should provide a program (command) the shows in a easier-to-read way the OTRv4 messages. Also need to provide functions that will be used by the other functions of toolkit.

Parser should be able to parse:

• Identity message
• Auth R message
• Auth I message
• Prekey message
• Non-interactive auth message
• Data messages
• OTRv4 error messages
• Query message
• Whitespace tag
• PlainText

Reference:
https://bugs.otr.im/lib/libotr/blob/master/README (TOOLKIT section)
https://bugs.otr.im/lib/libotr/tree/master/toolkit
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts

Implement forge DAKE and session keys transcript (Interactive)

Description:

DAKE and session keys function should be able to forge a DAKE transcript.

If Alice wants to forge a DAKE with Bob, this function will need:

For interactive:

• Alice's Client Profile
• Alice's long-term secret key
• Bob's Client Profile

Reference:
https://bugs.otr.im/lib/libotr/blob/master/README (TOOLKIT section)
https://bugs.otr.im/lib/libotr/tree/master/toolkit
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts
https://github.com/otrv4/otrv4/blob/master/otrv4.md#interactive-deniable-authenticated-key-exchange-dake
https://github.com/otrv4/otrv4/blob/master/otrv4.md#non-interactive-deniable-authenticated-key-exchange-dake
https://github.com/otrv4/otrv4/blob/master/otrv4.md#publishing-prekey-ensembles

Implement read and forge data message

Description:
Readforge function receive a data message and the encryption key for that data message. With this info it can check the MAC and then decrypt and show the message.

If a new text is given, the data message should be show with the new text.

Reference:
https://bugs.otr.im/lib/libotr/blob/master/README (TOOLKIT section)
https://bugs.otr.im/lib/libotr/tree/master/toolkit
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts

Add memory test with valgrind in CI

Build doesn't work

Make fails with:

make[2]: *** No rule to make target '/usr/local/lib/libotr.la', needed by 'otrng_parse'.  Stop.
make[2]: Leaving directory '/home/olabini/CAD/projects/libotr-ng-toolkit'
make[1]: *** [Makefile:558: all-recursive] Error 1
make[1]: Leaving directory '/home/olabini/CAD/projects/libotr-ng-toolkit'
make: *** [Makefile:393: all] Error 2

On Fedora 28. I do have libotr-ng installed in /usr/local. However, the libotr.la file doesn't exist - and indeed shouldn't be necessary, so I'm not sure why the toolkit build checks for that.

Implement show mac

Description:

Mackey function should derive and display a MAC key derived from a encryption key.

Reference:
https://bugs.otr.im/lib/libotr/blob/master/README (TOOLKIT section)
https://bugs.otr.im/lib/libotr/tree/master/toolkit
https://github.com/otrv4/otrv4/blob/master/otrv4.md#forging-transcripts
https://github.com/otrv4/otrv4/blob/master/otrv4.md#calculating-encryption-and-mac-keys
https://github.com/otrv4/libotr-ng/blob/fc86bd522a1f1a51e28c7ed1aaf3b1ffeb560f0f/src/key_management.c#L755

Refactor the exposed functions inside libotr-ng

Instead of use the regular header, the task is to create an internal.h to separate them.