Patent ID: 6125183
Filing Date: 2000-09-26
Classification: G06F,G11B,H04N

Abstract:
A method of encrypting and decrypting digital data such as text, numeric, images, pictures, especially tailored for optical compact discs; said method comprises of ciphering/deciphering and error detection and correction using algebraic method, namely Reed-Solomon code; said method characterised by the following steps:A. choose a primitive polynomial p(x) over Galois Field (GF) according to CD-standards;B. consider the data structure which are the values of different polynomials in said GFD=(d.sub.1, d.sub.2, d.sub.3, . . . d.sub.n)n is multiple of m;C. select a keyK=(k.sub.1, k.sub.2, k.sub.3, . . . , k.sub.m);D. generate a matrix of random variableR=(r.sub.ij)i=1,2,3, . . . ,m; j=1,2,3 . . . ,m;E. calculate the encryption vectorC=K.sunburst.R.sunburst. is multiplication over said GF=c.sub.i i=1,2,3, . . . ,m;F. enciphering the dataE=D+C+ is addition over said GF=e.sub.ij i=1,2,3, . . . ,m; j=1,2,3, . . . ,nG. apply scrambling of depth sE.fwdarw.E'e.sub.ij .fwdarw.e'.sub.i+(j-1)s,ji=1,2,3, . . . n; j=1,2,3, . . . ns; s any positive integer;H. encode E' according to CD-encoding standards;I. the output from H above is the enciphered data which are the values of the polynomials over said GF to be sent to the EFM modulation;J. the decryption method comprises the following steps:decode the data according to the CD-standards to produce the ciphered data E';descramble the ciphered data: E'.fwdarw.E;calculate the decryption vector:C=K.sunburst.R.sunburst. is multiplication over said GF;add deciphering key to recover the original data:D=E+C+ is addition over said GF.