1. A method in a receiving node for determining whether received data is encoded with a certain channel code candidate, the method comprising: obtaining data encoded with an unknown channel code; calculating, for two or more different syndrome checks, the respective posterior probabilities that the two or more different syndrome checks are satisfied, given the obtained data, wherein the two or more different syndrome checks are associated with the channel code candidate; combining the posterior probabilities calculated for the two or more different syndrome checks; and determining whether the channel code candidate was used for encoding the obtained data, based on the combined posterior probabilities.