Hej there! Found that e.g. Briar project recently did that. https://briarproject.org/raw/BRP-01-report.pdf
or Ricochet https://ricochet.im/files/ricochet-ncc-audit-2016-01.pdf What about security experts looking at GNU Ring's code? And a somehow related question in addition: Ricochet found a way to provide anonymous metadata-resistant instant messaging. Maybe that's something worth for you to look into? Thanks and have a beautiful day!
