This browser is no longer supported.
Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(83.2, 73%, 18%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ESS%3C/text%3E%3C/svg%3E)
Planned to integrate FIDO2 Webauthn for this we need to create the attestation object we followed https://www.w3.org/TR/webauthn-2/ and https://github.com/passwordless-lib/fido2-net-lib to create with tpm.
where for x5c we are passing the buildcertificate chain and sing the signature will use different public key, So verify is failing.
And need more information on KeyCredentialmanager's Attestation bufffer So that this can be used for creating FIDO2 tpm attestation object?
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(211.20000000000002, 92%, 30%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ERL%3C/text%3E%3C/svg%3E)
Are you developing a UWP app and you are using KeyCredentialmanager in your app?
yes https://github.com/MicrosoftDocs/windows-uwp/blob/docs/windows-apps-src/security/microsoft-passport-login-auth-service.md Need more info on KeyCredentialAttestationResult which has
I'll ask other engineers about this. There might be some time delay.
I've consulted the team. Could you please share more details about what exactly you are trying to do? What you are trying to accomplish and what's not working exactly or any errors related to this.
In UWP app, we are trying to creating FIDO TPM attestation object using keyCredentialManager (Hello).
Refer - TPM Attestation Statement Format(https://www.w3.org/TR/webauthn-2/#sctn-tpm-attestation)
we are signing the challenge using keyCredentialManager and trying to form the TPM attestation object with below parameters.
x5c - we are using CertificareChainbuffer build chain and passing Certificate[0]
aikCert
The AIK certificate used for the attestation, in X.509 encoding.
sig
The attestation signature, in the form of a TPMT_SIGNATURE structure as specified in [TPMv2-Part2] section 11.3.4.
certInfo
The TPMS_ATTEST structure over which the above signature was computed, as specified in [TPMv2-Part2] section 10.12.8.
pubArea
The TPMT_PUBLIC structure (see [TPMv2-Part2] section 12.2.4) used by the TPM to represent the credential public key.
Also need more info on AttestationBuffer what it contains?
So what's the real problem? Does it fail to create the object? Where and how did you use the AttestationBuffer property?
Created object - while verify its failing, as x5c public key is different from credential.retrievepublickey.
Not using AttestationBuffer Property. Need more info what it contains in detail, So as to use this.
I've talked with the team and discussed this. It's complex and it is not suitable to discuss in a public forum. For your scenario, I suggest that you might need to open a support ticket for this. Please contact our paid phone support at MS Support. You will get 1:1 support on that. Select Developer Tools -> Windows UWP Development -> Windows 10 Universal App Dev -> System Services Development->Security and cryptography on the support page and you could contact the team. Please kindly note that your support ticket will be free if it is Microsoft's issue.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(144, 52%, 23%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EJZ%3C/text%3E%3C/svg%3E)
You should give more details about AttestationBuffer and CertificareChainbuffer.
Hi guys, any updates?
Can you help explain more about AatestationBuffer?