diff --git a/native-certgen/src/lib.rs b/native-certgen/src/lib.rs
index 147ae6e..f91365f 100644
--- a/native-certgen/src/lib.rs
+++ b/native-certgen/src/lib.rs
@@ -1,3 +1,5 @@
+#![deny(clippy::unwrap_used, clippy::expect_used)]
+
 mod error;
 mod types;
 mod keygen;
@@ -5,3 +7,320 @@ pub mod keybox;
 pub mod attestation;
 pub mod certbuilder;
 pub mod logging;
+
+use jni::objects::{JByteArray, JClass, JIntArray, JObject, JString};
+use jni::sys::{jboolean, jbyteArray, jstring};
+use jni::JNIEnv;
+
+use crate::error::{CertGenError, Result};
+use crate::types::{Algorithm, CertGenParams, EcCurve};
+
+// ---------------------------------------------------------------------------
+// JNI entry: generateAttestedKeyPair
+// ---------------------------------------------------------------------------
+
+#[no_mangle]
+pub extern "system" fn Java_org_matrix_TEESimulator_pki_NativeCertGen_generateAttestedKeyPair(
+    mut env: JNIEnv,
+    _class: JClass,
+    config: JObject,
+) -> jbyteArray {
+    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+        generate_attested_inner(&mut env, &config)
+    }));
+
+    match result {
+        Ok(Ok(raw)) => raw,
+        Ok(Err(e)) => {
+            tracing::error!(%e, "generateAttestedKeyPair failed");
+            let _ = env.throw_new(
+                "java/lang/RuntimeException",
+                format!("NativeCertGen: {e}"),
+            );
+            std::ptr::null_mut()
+        }
+        Err(_) => {
+            tracing::error!("generateAttestedKeyPair panicked");
+            let _ = env.throw_new(
+                "java/lang/RuntimeException",
+                "NativeCertGen: internal panic",
+            );
+            std::ptr::null_mut()
+        }
+    }
+}
+
+fn generate_attested_inner(env: &mut JNIEnv, config: &JObject) -> Result<jbyteArray> {
+    let params = extract_config(env, config)?;
+
+    let key_pair = keygen::generate_key_pair(
+        params.algorithm,
+        params.key_size,
+        params.ec_curve,
+        params.rsa_public_exponent,
+    )?;
+
+    let keybox = keybox::parse_keybox(&params.keybox_cert_chain, &params.keybox_private_key)?;
+
+    let attest_ext = attestation::build_attestation_extension(&params)?;
+
+    let cert_chain = certbuilder::build_certificate_chain(
+        &key_pair,
+        &attest_ext,
+        &keybox,
+        &params,
+    )?;
+
+    let blob = assemble_result(&key_pair.private_key_pkcs8, &cert_chain);
+
+    let out = env.byte_array_from_slice(&blob)?;
+    Ok(out.into_raw())
+}
+
+// ---------------------------------------------------------------------------
+// JNI entry: initLogging
+// ---------------------------------------------------------------------------
+
+#[no_mangle]
+pub extern "system" fn Java_org_matrix_TEESimulator_pki_NativeCertGen_initLogging(
+    mut env: JNIEnv,
+    _class: JClass,
+    verbose: jboolean,
+    log_dir: JString,
+) -> jboolean {
+    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+        init_logging_inner(&mut env, verbose, &log_dir)
+    }));
+
+    match result {
+        Ok(Ok(())) => 1,
+        Ok(Err(e)) => {
+            let _ = env.throw_new(
+                "java/lang/RuntimeException",
+                format!("NativeCertGen initLogging: {e}"),
+            );
+            0
+        }
+        Err(_) => {
+            let _ = env.throw_new(
+                "java/lang/RuntimeException",
+                "NativeCertGen initLogging: internal panic",
+            );
+            0
+        }
+    }
+}
+
+fn init_logging_inner(env: &mut JNIEnv, verbose: jboolean, log_dir: &JString) -> Result<()> {
+    let dir: String = env.get_string(log_dir)?.into();
+    logging::init(verbose != 0, &dir, 2, 3)
+        .map_err(|e| CertGenError::Jni(format!("logging init failed: {e}")))?;
+    Ok(())
+}
+
+// ---------------------------------------------------------------------------
+// JNI entry: dumpLogs
+// ---------------------------------------------------------------------------
+
+#[no_mangle]
+pub extern "system" fn Java_org_matrix_TEESimulator_pki_NativeCertGen_dumpLogs(
+    mut env: JNIEnv,
+    _class: JClass,
+    _log_dir: JString,
+    _base_dir: JString,
+) -> jstring {
+    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+        dump_logs_inner(&mut env)
+    }));
+
+    match result {
+        Ok(Ok(raw)) => raw,
+        Ok(Err(e)) => {
+            tracing::error!(%e, "dumpLogs failed");
+            std::ptr::null_mut()
+        }
+        Err(_) => {
+            tracing::error!("dumpLogs panicked");
+            std::ptr::null_mut()
+        }
+    }
+}
+
+fn dump_logs_inner(env: &mut JNIEnv) -> Result<jstring> {
+    logging::dump::execute_dump()
+        .map_err(|e| CertGenError::Jni(format!("dump failed: {e}")))?;
+
+    // Read the dump path written by execute_dump
+    let path = std::fs::read_to_string("/data/adb/tricky_store/.dump_path")
+        .map_err(|e| CertGenError::Jni(format!("read dump path: {e}")))?;
+
+    let jpath = env.new_string(&path)?;
+    Ok(jpath.into_raw())
+}
+
+// ---------------------------------------------------------------------------
+// Config extraction from Java CertGenConfig object
+// ---------------------------------------------------------------------------
+
+fn extract_config(env: &mut JNIEnv, config: &JObject) -> Result<CertGenParams> {
+    let algorithm = get_int(env, config, "algorithm")?;
+    let key_size = get_int(env, config, "keySize")?;
+    let ec_curve_raw = get_int(env, config, "ecCurve")?;
+    let rsa_pub_exp = get_long(env, config, "rsaPublicExponent")?;
+
+    let cert_not_before = get_long(env, config, "certNotBefore")?;
+    let cert_not_after = get_long(env, config, "certNotAfter")?;
+    let security_level = get_int(env, config, "securityLevel")?;
+    let attest_version = get_int(env, config, "attestVersion")?;
+    let keymaster_version = get_int(env, config, "keymasterVersion")?;
+    let os_version = get_int(env, config, "osVersion")?;
+    let os_patch_level = get_int(env, config, "osPatchLevel")?;
+    let vendor_patch_level = get_int(env, config, "vendorPatchLevel")?;
+    let boot_patch_level = get_int(env, config, "bootPatchLevel")?;
+    let creation_datetime = get_long(env, config, "creationDatetime")?;
+
+    let attestation_challenge = get_nullable_byte_array(env, config, "attestationChallenge")?;
+    let purposes = get_int_array(env, config, "purposes")?;
+    let digests = get_int_array(env, config, "digests")?;
+    let cert_serial = get_nullable_byte_array(env, config, "certSerial")?;
+    let cert_subject = get_nullable_byte_array(env, config, "certSubject")?;
+    let keybox_private_key = get_byte_array(env, config, "keyboxPrivateKey")?;
+    let keybox_cert_chain = get_byte_array(env, config, "keyboxCertChain")?;
+    let boot_key = get_byte_array(env, config, "bootKey")?;
+    let boot_hash = get_byte_array(env, config, "bootHash")?;
+    let attestation_app_id = get_byte_array(env, config, "attestationApplicationId")?;
+    let module_hash = get_nullable_byte_array(env, config, "moduleHash")?;
+
+    let id_brand = get_nullable_byte_array(env, config, "idBrand")?;
+    let id_device = get_nullable_byte_array(env, config, "idDevice")?;
+    let id_product = get_nullable_byte_array(env, config, "idProduct")?;
+    let id_serial = get_nullable_byte_array(env, config, "idSerial")?;
+    let id_imei = get_nullable_byte_array(env, config, "idImei")?;
+    let id_meid = get_nullable_byte_array(env, config, "idMeid")?;
+    let id_manufacturer = get_nullable_byte_array(env, config, "idManufacturer")?;
+    let id_model = get_nullable_byte_array(env, config, "idModel")?;
+    let id_second_imei = get_nullable_byte_array(env, config, "idSecondImei")?;
+
+    Ok(CertGenParams {
+        algorithm: Algorithm::try_from(algorithm)?,
+        key_size: key_size as u32,
+        ec_curve: if algorithm == 3 {
+            Some(EcCurve::try_from(ec_curve_raw)?)
+        } else {
+            None
+        },
+        rsa_public_exponent: rsa_pub_exp as u64,
+        attestation_challenge,
+        purposes,
+        digests,
+        cert_serial,
+        cert_subject,
+        cert_not_before,
+        cert_not_after,
+        keybox_private_key,
+        keybox_cert_chain,
+        security_level,
+        attest_version,
+        keymaster_version,
+        os_version,
+        os_patch_level,
+        vendor_patch_level,
+        boot_patch_level,
+        boot_key,
+        boot_hash,
+        creation_datetime,
+        attestation_application_id: attestation_app_id,
+        module_hash,
+        id_brand,
+        id_device,
+        id_product,
+        id_serial,
+        id_imei,
+        id_meid,
+        id_manufacturer,
+        id_model,
+        id_second_imei,
+    })
+}
+
+// ---------------------------------------------------------------------------
+// JNI field accessor helpers — called 35+ times, justifies the abstraction
+// ---------------------------------------------------------------------------
+
+fn get_int(env: &mut JNIEnv, obj: &JObject, name: &str) -> Result<i32> {
+    Ok(env.get_field(obj, name, "I")?.i()?)
+}
+
+fn get_long(env: &mut JNIEnv, obj: &JObject, name: &str) -> Result<i64> {
+    Ok(env.get_field(obj, name, "J")?.j()?)
+}
+
+fn get_byte_array(env: &mut JNIEnv, obj: &JObject, name: &'static str) -> Result<Vec<u8>> {
+    let field = env.get_field(obj, name, "[B")?.l()?;
+    if field.is_null() {
+        return Err(CertGenError::NullParam(name));
+    }
+    let arr: JByteArray = field.into();
+    let len = env.get_array_length(&arr)?;
+    let mut buf = vec![0i8; len as usize];
+    env.get_byte_array_region(&arr, 0, &mut buf)?;
+    env.delete_local_ref(arr)?;
+    Ok(buf.into_iter().map(|b| b as u8).collect())
+}
+
+fn get_nullable_byte_array(
+    env: &mut JNIEnv,
+    obj: &JObject,
+    name: &str,
+) -> Result<Option<Vec<u8>>> {
+    let field = env.get_field(obj, name, "[B")?.l()?;
+    if field.is_null() {
+        return Ok(None);
+    }
+    let arr: JByteArray = field.into();
+    let len = env.get_array_length(&arr)?;
+    let mut buf = vec![0i8; len as usize];
+    env.get_byte_array_region(&arr, 0, &mut buf)?;
+    env.delete_local_ref(arr)?;
+    Ok(Some(buf.into_iter().map(|b| b as u8).collect()))
+}
+
+fn get_int_array(env: &mut JNIEnv, obj: &JObject, name: &str) -> Result<Vec<i32>> {
+    let field = env.get_field(obj, name, "[I")?.l()?;
+    if field.is_null() {
+        return Ok(vec![]);
+    }
+    let arr: JIntArray = field.into();
+    let len = env.get_array_length(&arr)?;
+    let mut buf = vec![0i32; len as usize];
+    env.get_int_array_region(&arr, 0, &mut buf)?;
+    env.delete_local_ref(arr)?;
+    Ok(buf)
+}
+
+// ---------------------------------------------------------------------------
+// Binary result assembly (doc 09 section 4.1)
+// ---------------------------------------------------------------------------
+
+fn assemble_result(private_key: &[u8], cert_chain: &[Vec<u8>]) -> Vec<u8> {
+    let total = 4 + private_key.len()
+        + 4
+        + cert_chain.iter().map(|c| 4 + c.len()).sum::<usize>();
+
+    let mut buf = Vec::with_capacity(total);
+
+    // Private key segment
+    buf.extend_from_slice(&(private_key.len() as u32).to_be_bytes());
+    buf.extend_from_slice(private_key);
+
+    // Cert count
+    buf.extend_from_slice(&(cert_chain.len() as u32).to_be_bytes());
+
+    // Each cert: length-prefixed DER
+    for cert in cert_chain {
+        buf.extend_from_slice(&(cert.len() as u32).to_be_bytes());
+        buf.extend_from_slice(cert);
+    }
+
+    buf
+}