  Several recently proposed code-based cryptosystems base their security on a
slightly generalized version of the classical (syndrome) decoding problem.
Namely, in the so-called restricted (syndrome) decoding problem, the error
values stem from a restricted set. In this paper, we propose new generic
decoders, that are inspired by subset sum solvers and tailored to the new
setting. The introduced algorithms take the restricted structure of the error
set into account in order to utilize the representation technique efficiently.
This leads to a considerable decrease in the security levels of recently
published code-based cryptosystems.
