Patent ID: 6981195

Claim:
A data transmission method including a cyclic redundancy check that uses efficient re-computation of an original error detection code in an original data message, the original data message further comprising an original payload, the original error detection code comprising a value determined according to an error detection formula using the original payload, the error detection formula having a first number of steps, the method comprising: receiving the original data message, obtaining a modified payload from the original payload using a payload transformation formula, obtaining a modified error detection code from the original error detection code using a modification formula having a second number of steps, forming a modified data message from the modified payload and the modified error detection code, and transmitting said modified data message, wherein the modification formula is different from the error detection formula and permits faster recomputation of the error detection code than using the error detection formula, and the modified error detection code is obtained from the modification formula without use of the original payload or the modified payload.