Arnaud Bannier and I have designed a full symmetric encryption algorithm containing an exploitable backdoor. Our paper which presents the algorithm has just been accepted for presentation at the First International Conference of FORmal Methods in Security Engineering (ForSE) 2017 in Porto, Portugal in February. Here is the abstract of our talk
The algorithm proposed in this paper is a first humble step in a long research work and we hope that it will incite research in an aera which is quite never addressed.
The solution on how to exploit this backdoor operationnally will be presented in exclusivity at the RusKrypto 2017 conference in Moscow.