Abstract: Error linear complexity of periodic sequences is an important indicator of the stability of the key stream.First,the algorithm for computing the k-error linear complexity of a sequence with a period pn over GF(q) is rewritten,and an efficient algorithm for m-tight error linear complexity of this sequence is given.Secondly,a method is given for computing an error vector which gives the k-error linear complexity.Here p is an odd prime and q is a primitive root modulus p².

Key words: k-error linear complexity, m-tight linear complexity, error vector