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. 02, 1997
Filed:
May. 17, 1996
Michael W Bright, Arlington Heights, IL (US);
Scott J Pappas, Streamwood, IL (US);
Kevin G Doberstein, Elmhurst, IL (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A method of decrypting retransmitted parts of a message includes receiving (201) a message comprising encryption synchronization and a plurality of encrypted blocks. Until a first block of the plurality of encrypted blocks is received with error, a first keystream is generated (205) from the encryption synchronization and at least one of the plurality of encrypted blocks, and, using the first keystream, the plurality of encrypted blocks, received without error before the first block of the plurality of encrypted blocks is received with error, is decrypted (207). A priming block is determined (211) from the message. When the first block of the plurality of encrypted blocks is received with error, a second message is transmitted (219) requesting a retransmission of the first block. Upon receiving the retransmission of the first block without error, a second keystream is generated (223) from the priming block and the retransmission of the first block and decrypting the retransmission of the first block is decrypted (225) using the second keystream.