Bernd RodlerandClaude Opus 4.8
d047891ded
Adds roundtrip.mjs, which drives the plugin's own modules directly — no browser, no DOM — and proves the three audit fixes did not break S/MIME. 24 assertions, all passing, against the self-signed spike certificates: PKCS#12 import (both identities, RSA-2048, kdf=600000) key encrypted at rest (32-byte salt, 12-byte IV) unlock yields NON-EXTRACTABLE keys; wrong passphrase rejected sign -> verify: signature valid, signer email matches From encrypt -> decrypt by the intended recipient, plaintext matches sender can read their own Sent copy downgraded message produces no plaintext Two results worth recording. Finding 1 is confirmed against a genuine CMS structure, not just a mock: the spike certs are self-signed, smimeVerify reports signatureValid AND signerEmailMatch true AND selfSigned true, and the gate refuses the auto-import. That is exactly the cert-substitution attack, blocked. The same status with selfSigned:false passes, so the gate is not simply refusing everything. Finding 2 is confirmed end to end: our own encrypt path produces AES-256-GCM, decrypt reports contentAuthenticated:true, so HTML renders without suppression. Only legacy inbound CBC degrades to text. The section-8 assertion is deliberately loose. Swapping the 9-byte AES-GCM OID for the 8-byte 3DES OID also invalidates the enclosing DER lengths, so ASN.1 validation rejects the message before the allowlist is reached — either way no plaintext is produced, and the assertion says which path fired rather than pretending it tested the allowlist. The allowlist itself is asserted precisely in verify-fixes.mjs, which now carries 36 assertions including checks that fail if a legacy CBC OID reappears or the mail path stops using the native engine. Browser-side spike result: the patched plugin installs through the admin channel, resolves to the privileged tier, and activates with "hooks=5, slots=3" and no refusals — so the B-04 gate does not block it. Its S/MIME settings section renders and survives SPA navigation. Key import via the UI could not be automated (native file picker), which is a harness limit rather than a product defect; roundtrip.mjs covers that path directly instead. Findings 4, 5 and 6 remain open. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>