Patent ID: 7688977

Claim:
A computer implemented method for encrypting video data in which: a set of n video data blocks VB(b 1 b 2 . . . b n ) is generated from a video data set V(v 1 ,v 2 . . . v L ) comprising L data units v x (1≦x≦L) by partitioning a subset of video data V′(v d+1 v d+2 . . . v L ), 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(v 1 v 2 . . . v L ) comprising L data units v x ; one half of the n video data blocks VB(b 1 b 2 . . . b n ) 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=p 1 p 2 . . . p n/2 to create a temporary cipher text T=t 1 t 2 . . . t L-d , the permutation list P=p 1 p 2 . . . P n/2 being generated by means of a key stream S(s 1 s 2 . . . s l ) 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=t 1 t 2 . . . t L-d and a subset of d video data (v 1 v 2 . . . v d ) from the video data set V(v 1 v 2 . . . v L ), which remain unaccounted for when generating the set of n video data blocks VB(b 1 b 2 . . . b n ) into a cipher text C(c 1 c 2 . . . c L ) comprising L data units cy(1≧y≧L); wherein the prior steps are performed by a computer.