Method for encrypting video data

A computer implemented method for encrypting video data in which:

• a set of n video data blocks VB(b1b2 . . . bn) is generated from a video data set V(v1,v2 . . . vL) comprising L data units vx (1≦x≦L) by partitioning a subset of video data V′(vd+1vd+2 . . . vL), where n is an even number and d (d=0, 1, 2, . . . ) is a number of data units at the beginning of the video data set V(v1v2 . . . vL) comprising L data units vx;
• one half of the n video data blocks VB(b1b2 . . . bn) is assigned to one half set of video data blocks comprising n/2 first video data blocks and assigning the other half to a second half set of video data blocks comprising n/2 second video data blocks as claimed;
• the n/2 first video data blocks from the first half set and the n/2 second video data blocks from the second half set are interchanged pairwise in accordance with a permutation list P=p1p2 . . . pn/2 to create a temporary cipher text T=t1t2 . . . tL-d, the permutation list P=p1p2 . . . Pn/2 being generated by means of a key stream S(s1s2 . . . sl) derived from a stream cipher and comprising l key elements, where l is a predefined constant number;
• subsequently an encrypted set of video data is generated by encrypting the temporary cipher text T=t1t2 . . . tL-d and a subset of d video data (v1 v2 . . . vd) from the video data set V(v1v2 . . . vL), which remain unaccounted for when generating the set of n video data blocks VB(b1b2 . . . bn) into a cipher text C(c1c2 . . . cL) comprising L data units cy(1≧y≧L);
• wherein the prior steps are performed by a computer.