fix(webauthn): offer RS256 for the PRF-wrapping credential - #142
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Chromium warns when `pubKeyCredParams` offers neither ES256 nor RS256, and surfaces the warning in chrome://extensions as an error against the extension — where it sits beside real faults and costs a reader the time to rule it out. One did exactly that while diagnosing an unrelated mediator problem. The credential enrolled here exists only to carry the PRF extension: the wallet consumes `prf.results.first` and never verifies a signature from it, and the PRF output does not depend on the key's algorithm. So admitting RSA costs nothing and widens the set of authenticators that can hold the wrapping secret. Deliberately not applied to `enrollPasskey` in core, whose key IS registered as a DID verification method: `importSpkiForAlg` accepts only ES256/EdDSA/ES384, so an RSA credential there would enroll and then fail to import. The comment says so at the point someone would copy it. Signed-off-by: Glenn Gore <glenn.g@affinidi.com>
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What
Adds RS256 (
alg: -257) topubKeyCredParamsfor the WebAuthn credential that carries the PRF extension, last in the preference list after EdDSA and ES256.Why
Chromium warns when
pubKeyCredParamsoffers neither ES256 nor RS256:It surfaces in
chrome://extensionsas an error against the extension, where it sits next to real faults. A user hit exactly that while diagnosing an unrelated mediator connectivity problem, and it cost time to rule out.The credential enrolled in
enrollOrLoadCredentialexists only to carry the PRF extension — the wallet consumesprf.results.firstand never verifies a signature from it, and the PRF output is independent of the key's algorithm. Admitting RSA therefore costs nothing and widens the set of authenticators that can hold the wallet's wrapping secret.What this deliberately does not touch
enrollPasskeyinpackages/core/src/webauthn/register.tskeeps ES256/EdDSA only. That key is registered as a DID verification method, andimportSpkiForAlgaccepts only ES256/EdDSA/ES384 — an RSA credential there would enroll successfully and then fail to import. The comment records this at the point someone would be tempted to copy the change across.Pre-merge checklist
npm run lintcleannpm run buildcleannpm test— all suites passdist/background.jssingle bundle, no dynamicimport(), nochrome.cookies, no staticcontent_scripts