Attestation is how a remote party gains confidence that a key really lives in tamper-resistant hardware rather than in software an attacker could lift. The device produces a signed statement vouching that the key sits behind a genuine secure module. The catch is that the most straightforward way to do this also identifies the device uniquely — trading privacy for trust.

US11750591B2, “Key attestation statement generation providing device anonymity,” granted to Microsoft Technology Licensing on September 5, 2023, tries to keep both halves. Classified under H04L 63/0823 (network authentication using certificates) with a stack of key-management codes, it claims generating an attestation that proves hardware-backing without uniquely identifying the device.

“A computing device sends a request for an attestation certificate to an attestation service along with information regarding the hardware and/or software of the device. The attestation service processes the request and verifies the information received from the device.”— U.S. Patent No. 11,750,591 source

The tension the claim resolves is real and widely felt. Enterprises and services increasingly demand that keys be hardware-backed — stored in a TPM or secure element — before they trust them. But a naive attestation reveals a device-unique identifier, which becomes a tracking handle. Privacy-respecting attestation has to let a device say “my key is hardware-backed, trust it” without also saying “and here is exactly which machine I am, every time.”

This puts the patent in the lineage of anonymous-attestation and group-signature ideas, where a member can prove membership in a trusted set without revealing which member it is. The practical payoff is that you can require hardware-backed keys across a fleet without turning every authentication into a surveillance event.

Per the desk's rules: issued grant (B2), not an application; a method claim, not a shipped feature — though Microsoft's Windows attestation and TPM ecosystem is the obvious backdrop. The privacy-preserving framing is the distinctive part of the claim.

For the systems reader, this sits at a useful intersection: hardware security, identity, and privacy. As hardware-backed keys become table stakes, the question shifts from “can you attest?” to “can you attest without being tracked?” — and that is exactly the gap this grant stakes out.