Federal Circuit Affirms Summary Judgment That Sonos Does Not Infringe a Digital Rights Management Patent Asserted by Google.

On October 30, 2026, the Federal Circuit affirmed, in a nonprecedential opinion by Judge J. Campbell Barker of the Eastern District of Texas, sitting by designation, joined by Judges Stoll and Stark, the Northern District of California's summary judgment that Sonos, Inc. does not infringe claims 1 and 10 of U.S. Patent 7,899,187, asserted by Google LLC. The court agreed that a device "utilize[s]" the claimed private key only by decrypting with it, and that a "private key" must be a key input to a cryptographic algorithm, constructions that disposed of both of Google's infringement theories.

The appeal

The case is Google LLC v. Sonos, Inc., No. 2025-1346 (Fed. Cir. Oct. 30, 2026) (nonprecedential), an appeal from No. 3:20-cv-03845-EMC in the Northern District of California, where Judge Edward M. Chen granted Sonos summary judgment of non-infringement. The Federal Circuit had jurisdiction under 28 U.S.C. 1295(a)(1) and reviewed the summary judgment de novo.

What the claims recite

The '187 patent is titled "Domain-Based Digital-Rights Management System with Easy and Secure Device Enrollment." Google asserted independent claims 1 and 10. Claim 1 recites a method for registering a new device as part of a domain of devices that share rights associated with a common account, for use in accessing protected digital content within a digital-rights management system. The method receives domain information from a device existing within the domain, provides the domain information to a key issuer that is separate from the domain, causing the key issuer to issue a private key to the new device, and receives the private key. The claim requires that the private key "is based on the domain information and is utilized by all devices within the domain of devices." Claim 10 recites an apparatus with communication circuitry that receives the domain information, storage for it, and logic circuitry that provides it to a key issuer separate from the domain, causing the key issuer to issue a private key to the apparatus, with the same "utilized by all devices" requirement.

The accused Sonos system

According to the opinion, Sonos speakers can be grouped into a "household" through the Sonos Controller app. Only one player in a group receives an encrypted music stream, and that player uses a unique private key to decrypt the content before sending the decrypted content to the other group members for playback. To connect a household to a streaming service, the Controller obtains an authorization token from the service and shares it with the players, and a player that joins later obtains the token from an existing player and authenticates itself by presenting the token to the streaming service. It was undisputed that no Sonos player ever uses the authorization token as a cryptographic key input to a cryptographic algorithm.

Google's two theories

Under Google's Strong-Encryption Theory, when one Sonos device decrypts content with a private key and distributes it, every device in the household has "utilized" the key. Under its Authentication Theory, the authorization token satisfies the "private key" limitation because it is an input to a cryptographic algorithm. The district court rejected both. It held that a device does not "utilize" a private key merely by obtaining decrypted content from another device that ran the algorithm, and it construed "private key" as a "non-public cryptographic key that is used as the key input (rather than solely as the data input) to a cryptographic algorithm."

To utilize a private key is to decrypt with it

The Federal Circuit adopted Sonos's construction of "utilized." It read the claim as requiring that the new device receive a private key and that all devices utilize it, and it pointed to the specification's statements that a device "must access DRM private key . . . and uses [sic] it to decrypt the content encryption key." The court found "only evidence that supports the idea that a person of ordinary skill in the art would understand that to 'utilize' a private key is to decrypt with it." It rejected Google's claim differentiation argument based on dependent claim 6, explaining that both claims still require the key to be utilized by all devices. It added that Google "offers no persuasive limiting principle" on when indirect use of a key would be too attenuated, and that "constructions that are more likely to result in an indefinite claim should be avoided." Because the parties agreed that all but one player per household only indirectly uses the key, no genuine fact issue remained on the Strong-Encryption Theory.

A private key is a key input

On the Authentication Theory, the court again agreed with Sonos. It relied on the specification's explanation that "[t]he private key is used for either decrypting data or generating digital signatures," on claim 6, in which the private key is the key input that decrypts a second encryption key, and on Sonos's extrinsic evidence that a key is "the thing that acts upon data, information, or a message." The court held that a person of ordinary skill "would understand the 'private key' to necessarily be a key input to a cryptographic algorithm." Because the constructions of "utilized" and "private key" were dispositive, the court did not reach Google's arguments about its expert's alleged concession or the "based on" limitation, and it affirmed.

What to watch next

Watch for any petition for rehearing.

Cite this page: https://patentlitigator.com/analysis/google-v-sonos-drm-patent-7899187-noninfringement-affirmed/