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.
EC keygen now returns proper SPKI DER instead of raw point bytes.
RSA keygen uses caller-supplied exponent via new_with_exp() and
validates key size to 2048/3072/4096. Keybox parser extracts leaf
subject DN (not issuer). Added AttestKey=7 to KeyPurpose. Realigned
error variants with spec.
Cargo.toml with 16 dependencies per build spec, error types with
From impls for all upstream error types, CertGenParams mapping the
full JNI config contract, EC/RSA key generation via ring and rsa crates.
Compiles clean for aarch64-linux-android via cargo-ndk.
Enginex0