Study On Algorithms For Measure Indexes Of Stream Ciphers And Their Stability

This disseitation mainly discusses algorithms for measure indexes of stream ciphers and their stability, the main results that the author obtained are as follows: (1) A theorem is pmpsed for the linear complexity of binaiy sequences over GF(2) with period n昚? (2) A fast algorithm is given for the linear complexity of sequences over GF(2) with period n2~? (3) On the basis of a fast algorithm for the linear complexity of sequences over GF(2) with period n ~2 ~ , a fast algorithm is prsented for the k-enor linear complexity of sequences over GF(2) with period n 2v. (4) A new relation is presened for a sequence with important vector in the fast algorithm for the linear complexity of sequences over GF(q) with period pfl~ (5) The Stamp-Martin algorithm is generalized to sequences over GF(q) with period pfl? (6) A algorithm on the error vector and the count of sequences with the k-error linear complexity over GF(2) , period I , and the Stamp-Martin algorithm is improved. (7) A algorithm is generalized for the eimr vector and the count of sequences with the k- error linear complexity over GF(2) to over GFQiJ with period pfl? (8) A Lower bound is discussed for the k-error linear complexity over GF(2) and GF(q), we give theorems on he k-error linear complexity.