Recovering a code´s length and synchronization from a noisy intercepted bitstream

We focus on the problem of recovering the length and synchronization of a linear block code from an intercepted bitstream. We place ourselves in an operational context where the intercepted bitstream contains a realistic noise level. We present two algorithms, one due to Valembois and the other one brand new. They are both useful in different contexts, able to verify if a given length/synchronization is correct. Using them, we were able to practically recover the synchronization of several codes.