The automorphism group of double-error-correcting BCH codes

Using the description of primitive cyclic codes in a modular algebra, the author characterizes the permutations of the support of a cyclic code which leaves the code globally invariant. Applying this result to the binary double-error-correcting BCH codes, the author proves that the automorphism group of such a code (of length 2^m -1,m>4) is the semi-linear group of GF(2^m) over GF(2 ^m), and, in the special case m=4, the semi-linear group of GP(16) over GF(4)