DuckDetector flagged two issues:
1. Oversized challenge accepted, 256-byte attestation challenge should
return INVALID_INPUT_LENGTH (-21) like real KeyMint. Added early check
in handleGenerateKey before any path decision.
2. Issuer/subject chain mismatch, rcgen's HashMap loses DN attribute
ordering and converts PrintableString to UTF8String, producing
different DER bytes. Replaced rcgen with manual DER assembly that
injects raw keybox issuer_dn_der bytes directly.
Verified on device: TX_ID 315 rejects 256-byte challenge, TX_ID 501
generates valid 4-cert chain with correct issuer linkage.
Remove ENCRYPT/VERIFY from KeyUsage mapping to match Kotlin behavior.
Document BasicConstraints and SKI suppression via rcgen NoCa default.
Fix rotating log off-by-one that kept one extra backup file. Handle
BMPString (UTF-16BE) and VisibleString in X.500 DN parser.
Builds v3 leaf certificate with attestation extension and KeyUsage,
signs with keybox private key via rcgen 0.13.2. Assembles full chain
(leaf + keybox intermediates + root). Supports EC and RSA keybox
signing keys. Uses rcgen's signed_by() with a synthesized issuer
Certificate, no manual DER fallback needed.
Enginex0