Credential overwrite protection leaks information about the stored credentials

[szszszsz]

The lately introduced credential overwrite protection leaks information about the stored credentials in the PIN-encrypted space, when Update or Register commands are called with the already used credential label, but only if directly asked about it.

This can be addressed with changing the target file name calculation, by prefixing to be hashed credential label with the used encryption method, thus effectively separating logically the credential name spaces.

(edit: corrected last paragraph)

[robin-nitrokey]

Would you add the namespace only on the device or also for the credential IDs returned to the host? Either way, that would be difficult to solve in the UI unless we completely separate PIN-protected and non-PIN-protected credentials.

[szszszsz]

Only for the device. It should suffice to make the final file name hash to be a function of the encryption method.