So who else has seen this 'Enforce attestation' setting and didn't really understand what it does?
Well you can count me as one of the clueless until today. So I had to create this visual so I won't forget it the next time. (Bookmark this!)π
What is Passkey Attestation? β
Passkey attestation is a verification process that ensures:
π― The passkey was created by a legitimate, trusted authenticator β
π― The authenticator meets security and compliance requirements π
π― The passkey is hardware-backed and meets organizational security policies π’
π For FIDO2 Security Keys:
β Microsoft relies on the FIDO Alliance Metadata Service (MDS) to validate security keys
β During registration, security keys must provide a "packed" attestation statement as defined by the FIDO standard
β The attestation certificate must chain back to roots in the FIDO Alliance MDS
β Each security key has an Authenticator Attestation GUID (AAGUID) - a 128-bit identifier indicating the key type and model
π±For Microsoft Authenticator:
β π iOS: Uses the iOS App Attest service to verify the legitimacy of the Authenticator app.
β π€ Android: Uses two methods:
β Play Integrity API to verify app legitimacy.
β Android key attestation to verify hardware backing.
ποΈ Configuration Options
Administrators can configure attestation enforcement in the Passkey (FIDO2) authentication method policy:
π Enforce attestation = Yes : Only allows registration of attested passkeys from verified vendors/apps.
π Enforce attestation = No : Allows any passkey but still collects attestation data.
Requirements for Vendor Compliance βοΈ
β
For FIDO2 security keys to pass attestation when enforcement is enabled:
β
FIDO2 certification at any level π
β
Metadata published to FIDO Alliance MDS π
β
Support for FIDO 2.0 or higher β¬οΈ
β
User verification capability (biometrics or PIN) π
β
Resident keys (discoverable credentials) π
β
HMAC secret or PRF extension support π
π Benefits
π Security Assurance: Ensures only legitimate, hardware-backed passkeys are registered π°
π Vendor Verification: Validates that passkeys come from trusted manufacturers/providers π€
π Compliance: Helps organizations meet security requirements by blocking potentially compromised authenticators π
π Hardware Backing: Ensures passkeys are stored in secure hardware elements
π€ Limitations and Considerations
β βοΈ Attestation relies on external services (Apple, Google) which can experience outages
β β³ There may be up to a 4-week delay for new security keys to be recognized after appearing in FIDO Alliance MDS
β π Heavy service usage can cause registration failures requiring retry attempts
To learn more see:
β Entra ID attestation vendors -
learn.microsoft.com/en-us/enβ¦
β Enable passkeys in Authenticator -
learn.microsoft.com/en-us/enβ¦
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