Splits concatenated DER cert chains into individual certificates,
extracts leaf issuer DN and notAfter via x509-cert crate. Handles
multi-byte DER length encoding (0x81-0x84).
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