Cyclic redundancy check with efficient re-computation of error detection code

Efficient re-computation of an error detection code is achieved with an original data message that includes a payload and an error detection code. The error detection code comprises a value determined according to an error detection formula using the payload. The payload is modified using a payload transformation formula. The error detection code is re-computed from the original error detection code, rather than from the modified payload. The formula for re-computing the error detection code is different from the formula used to originally obtain the error detection formula, and does not use the original payload or the modified payload.