US 11,943,491 B2
Content protection
Christian Schwarz, Vuarrens (CH); Andre Nicoulin, Lausanne (CH); and Didier Hunacek, Blonay (CH)
Assigned to NAGRAVISION Sárl, Cheseaux-sur-Lausanne (CH)
Filed by NAGRAVISION Sarl, Cheseaux-sur-Lausanne (CH)
Filed on Apr. 24, 2023, as Appl. No. 18/306,085.
Application 17/147,349 is a division of application No. 16/075,102, granted, now 10,931,983, issued on Feb. 23, 2021, previously published as PCT/EP2016/065129, filed on Jun. 29, 2016.
Application 18/306,085 is a continuation of application No. 17/147,349, filed on Jan. 12, 2021, granted, now 11,671,637.
Claims priority of application No. 15174332 (EP), filed on Jun. 29, 2015.
Prior Publication US 2023/0353799 A1, Nov. 2, 2023
Int. Cl. H04N 21/2347 (2011.01); G06F 21/57 (2013.01); H04L 9/16 (2006.01); H04L 9/32 (2006.01); H04N 7/167 (2011.01); H04N 21/266 (2011.01); H04N 21/418 (2011.01); H04N 21/4405 (2011.01); H04N 21/4623 (2011.01)
CPC H04N 21/2347 (2013.01) [G06F 21/57 (2013.01); H04L 9/16 (2013.01); H04L 9/3213 (2013.01); H04N 7/167 (2013.01); H04N 21/26606 (2013.01); H04N 21/26613 (2013.01); H04N 21/4181 (2013.01); H04N 21/4405 (2013.01); H04N 21/4623 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A method of decrypting encrypted media content, the method comprising:
(a) receiving an encrypted media content stream on a client device;
(b) receiving an encrypted content key for decrypting the encrypted media content;
(c) storing the encrypted content key in a key table;
(d) authenticating and then decrypting the encrypted content key;
(e) loading the content key to a register of a descrambler to decrypt the media content stream;
(f) preventing further loading of the content key from the key table to the register;
(g) decrypting a predefined portion of the encrypted media content stream with the content key in the register using the descrambler;
(h) clearing the content key from the register when decryption of the predefined portion is complete; and
(i) repeating steps (c) to (h) to decrypt a next predefined portion of the encrypted media content stream.