The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 22, 2015
Filed:
Oct. 03, 2013
Nagravision S.a., Cheseaux-sur-Lausanne, CH;
Jean-Philippe Aumasson, Vuibroye, CH;
NAGRAVISION S.A., Cheseaux-sur-Lausanne, CH;
Abstract
Method and System for encrypting plaintext digital data divided into a sequence comprising successive plaintext blocks of a same length of bits each and a residual plaintext block having a length of bits lower than the length of one of the successive plaintext blocks. The successive plaintext blocks are ciphered with the main encryption key by using a ciphering algorithm based on a cipher block chaining mode to obtain a sequence of successive ciphered blocks having the same length as the successive plaintext blocks. A set of round keys having a same length, are generated by applying a key schedule function on a string obtained by adding the last ciphered block to the main encryption key. The round keys of the set are added together to obtain a resulting string having a length equal to the length of a block of the sequence. The residual plaintext block is then added to the most left bits of the resulting string forming a string) having a length equal to the length of the residual block to obtain a residual ciphered block. The method and the system apply also to decipher a sequence of successive ciphered blocks followed by a residual ciphered block.