A SageMath script to extract the BiviumA algebraic equations, and solve it via a SAT solver.
Here the CryptoMiniSat is used as the solver, so if you want to execute this script in your own installed SageMath, you need to install an optional package called cryptominisat on your SageMath, by the following commands.
sage -i cryptominisat
sage -b
[1] Attacking Bivium with MiniSat
[2] An Algebraic Analysis of Trivium Ciphers based on the Boolean Satisfiability Problem