diff --git a/microdroid_manager/Android.bp b/microdroid_manager/Android.bp
index 8710e54..93f49ef 100644
--- a/microdroid_manager/Android.bp
+++ b/microdroid_manager/Android.bp
@@ -46,10 +46,12 @@
         "libserde",
         "libserde_cbor",
         "libserde_json",
+        "libservice_vm_comm",
         "libthiserror",
         "libuuid",
         "libvsock",
         "librand",
+        "libzeroize",
     ],
     init_rc: ["microdroid_manager.rc"],
     multilib: {
@@ -70,6 +72,7 @@
     defaults: ["microdroid_manager_defaults"],
     test_suites: ["general-tests"],
     rustlibs: [
+        "libhwtrust",
         "libtempfile",
     ],
     multilib: {
diff --git a/microdroid_manager/aidl/Android.bp b/microdroid_manager/aidl/Android.bp
index 0aa8662..353e9cc 100644
--- a/microdroid_manager/aidl/Android.bp
+++ b/microdroid_manager/aidl/Android.bp
@@ -5,8 +5,12 @@
 aidl_interface {
     name: "android.system.virtualization.payload",
     srcs: ["android/system/virtualization/payload/*.aidl"],
+    imports: ["android.system.virtualizationcommon"],
     unstable: true,
     backend: {
+        java: {
+            enabled: false,
+        },
         rust: {
             enabled: true,
             apex_available: [
diff --git a/microdroid_manager/aidl/android/system/virtualization/payload/IVmPayloadService.aidl b/microdroid_manager/aidl/android/system/virtualization/payload/IVmPayloadService.aidl
index b9a7a64..51796f1 100644
--- a/microdroid_manager/aidl/android/system/virtualization/payload/IVmPayloadService.aidl
+++ b/microdroid_manager/aidl/android/system/virtualization/payload/IVmPayloadService.aidl
@@ -16,11 +16,17 @@
 
 package android.system.virtualization.payload;
 
+import android.system.virtualizationcommon.Certificate;
+
 /**
  * This interface regroups the tasks that payloads delegate to
  * Microdroid Manager for execution.
  */
 interface IVmPayloadService {
+    /** The constants STATUS_* are status code returned by this service. */
+    /** Failed to prepare the CSR and key pair for attestation. */
+    const int STATUS_FAILED_TO_PREPARE_CSR_AND_KEY = 1;
+
     /** Socket name of the service IVmPayloadService. */
     const String VM_PAYLOAD_SERVICE_SOCKET_NAME = "vm_payload_service";
 
@@ -33,6 +39,32 @@
      */
     const String ENCRYPTEDSTORE_MOUNTPOINT = "/mnt/encryptedstore";
 
+    /**
+     * An {@link AttestationResult} holds an attested private key and the remotely
+     * provisioned certificate chain covering its corresponding public key.
+     */
+    parcelable AttestationResult {
+        /**
+         * DER-encoded ECPrivateKey structure specified in [RFC 5915 s3] for the
+         * EC P-256 private key, which is attested.
+         *
+         * The corresponding public key is included in the leaf certificate of
+         * the certificate chain.
+         *
+         * [RFC 5915 s3]: https://datatracker.ietf.org/doc/html/rfc5915#section-3
+         */
+        byte[] privateKey;
+
+        /**
+         * Sequence of DER-encoded X.509 certificates that make up the attestation
+         * key's certificate chain.
+         *
+         * The certificate chain starts with a root certificate and ends with a leaf
+         * certificate covering the attested public key.
+         */
+        Certificate[] certificateChain;
+    }
+
     /** Notifies that the payload is ready to serve. */
     void notifyPayloadReady();
 
@@ -75,7 +107,9 @@
      * serving as proof of the freshness of the result.
      *
      * @param challenge the maximum supported challenge size is 64 bytes.
-     * @return the X.509 encoded certificate.
+     *
+     * @return An {@link AttestationResult} parcelable containing an attested key pair and its
+     *         certification chain.
      */
-    byte[] requestAttestation(in byte[] challenge);
+    AttestationResult requestAttestation(in byte[] challenge);
 }
diff --git a/microdroid_manager/src/vm_payload_service.rs b/microdroid_manager/src/vm_payload_service.rs
index 5b5fb9e..0661314 100644
--- a/microdroid_manager/src/vm_payload_service.rs
+++ b/microdroid_manager/src/vm_payload_service.rs
@@ -15,16 +15,38 @@
 //! Implementation of the AIDL interface `IVmPayloadService`.
 
 use android_system_virtualization_payload::aidl::android::system::virtualization::payload::IVmPayloadService::{
-    BnVmPayloadService, IVmPayloadService, VM_PAYLOAD_SERVICE_SOCKET_NAME};
+    BnVmPayloadService, IVmPayloadService, VM_PAYLOAD_SERVICE_SOCKET_NAME, AttestationResult::AttestationResult,
+    STATUS_FAILED_TO_PREPARE_CSR_AND_KEY
+};
 use android_system_virtualmachineservice::aidl::android::system::virtualmachineservice::IVirtualMachineService::IVirtualMachineService;
 use anyhow::{anyhow, Context, Result};
 use avflog::LogResult;
-use binder::{Interface, BinderFeatures, ExceptionCode, Strong, IntoBinderResult};
-use diced_open_dice::DiceArtifacts;
+use binder::{Interface, BinderFeatures, ExceptionCode, Strong, IntoBinderResult, Status};
+use diced_open_dice::{DiceArtifacts, derive_cdi_leaf_priv, PrivateKey, sign};
 use log::info;
 use rpcbinder::RpcServer;
+
+use crate::vm_secret::VmSecret;
+use coset::{
+    iana, CborSerializable, CoseKey, CoseKeyBuilder, CoseSign, CoseSignBuilder, CoseSignature,
+    CoseSignatureBuilder, HeaderBuilder,
+};
+use openssl::{
+    bn::{BigNum, BigNumContext},
+    ec::{EcGroup, EcKey, EcKeyRef},
+    ecdsa::EcdsaSig,
+    nid::Nid,
+    pkey::Private,
+    sha::sha256,
+};
+use service_vm_comm::{Csr, CsrPayload};
 use std::os::unix::io::OwnedFd;
-use crate::vm_secret::{VmSecret};
+use zeroize::Zeroizing;
+
+const ATTESTATION_KEY_NID: Nid = Nid::X9_62_PRIME256V1; // NIST P-256 curve
+const ATTESTATION_KEY_ALGO: iana::Algorithm = iana::Algorithm::ES256;
+const ATTESTATION_KEY_CURVE: iana::EllipticCurve = iana::EllipticCurve::P_256;
+const ATTESTATION_KEY_AFFINE_COORDINATE_SIZE: i32 = 32;
 
 /// Implementation of `IVmPayloadService`.
 struct VmPayloadService {
@@ -66,12 +88,111 @@
         Ok(self.secret.dice().cdi_attest().to_vec())
     }
 
-    fn requestAttestation(&self, challenge: &[u8]) -> binder::Result<Vec<u8>> {
+    fn requestAttestation(&self, challenge: &[u8]) -> binder::Result<AttestationResult> {
         self.check_restricted_apis_allowed()?;
-        self.virtual_machine_service.requestAttestation(challenge)
+        let (private_key, csr) = generate_attestation_key_and_csr(challenge, self.secret.dice())
+            .map_err(|e| {
+                Status::new_service_specific_error_str(
+                    STATUS_FAILED_TO_PREPARE_CSR_AND_KEY,
+                    Some(format!("Failed to prepare the CSR and key pair: {e:?}")),
+                )
+            })
+            .with_log()?;
+        let cert_chain = self.virtual_machine_service.requestAttestation(&csr)?;
+        Ok(AttestationResult {
+            privateKey: private_key.as_slice().to_vec(),
+            certificateChain: cert_chain,
+        })
     }
 }
 
+fn generate_attestation_key_and_csr(
+    challenge: &[u8],
+    dice_artifacts: &dyn DiceArtifacts,
+) -> Result<(Zeroizing<Vec<u8>>, Vec<u8>)> {
+    let group = EcGroup::from_curve_name(ATTESTATION_KEY_NID)?;
+    let attestation_key = EcKey::generate(&group)?;
+    let csr = build_csr(challenge, attestation_key.as_ref(), dice_artifacts)?;
+
+    let csr = csr.into_cbor_vec().context("Failed to serialize CSR")?;
+    let private_key = attestation_key.private_key_to_der()?;
+    Ok((Zeroizing::new(private_key), csr))
+}
+
+fn build_csr(
+    challenge: &[u8],
+    attestation_key: &EcKeyRef<Private>,
+    dice_artifacts: &dyn DiceArtifacts,
+) -> Result<Csr> {
+    // Builds CSR Payload to be signed.
+    let public_key =
+        to_cose_public_key(attestation_key)?.to_vec().context("Failed to serialize public key")?;
+    let csr_payload = CsrPayload { public_key, challenge: challenge.to_vec() };
+    let csr_payload = csr_payload.into_cbor_vec()?;
+
+    // Builds signed CSR Payload.
+    let cdi_leaf_priv = derive_cdi_leaf_priv(dice_artifacts)?;
+    let signed_csr_payload = build_signed_data(csr_payload, &cdi_leaf_priv, attestation_key)?
+        .to_vec()
+        .context("Failed to serialize signed CSR payload")?;
+
+    // Builds CSR.
+    let dice_cert_chain = dice_artifacts.bcc().ok_or(anyhow!("bcc is none"))?.to_vec();
+    Ok(Csr { dice_cert_chain, signed_csr_payload })
+}
+
+fn build_signed_data(
+    payload: Vec<u8>,
+    cdi_leaf_priv: &PrivateKey,
+    attestation_key: &EcKeyRef<Private>,
+) -> Result<CoseSign> {
+    let cdi_leaf_sig_headers = build_signature_headers(iana::Algorithm::EdDSA);
+    let attestation_key_sig_headers = build_signature_headers(ATTESTATION_KEY_ALGO);
+    let aad = &[];
+    let signed_data = CoseSignBuilder::new()
+        .payload(payload)
+        .try_add_created_signature(cdi_leaf_sig_headers, aad, |message| {
+            sign(message, cdi_leaf_priv.as_array()).map(|v| v.to_vec())
+        })?
+        .try_add_created_signature(attestation_key_sig_headers, aad, |message| {
+            ecdsa_sign(message, attestation_key)
+        })?
+        .build();
+    Ok(signed_data)
+}
+
+/// Builds a signature with headers filled with the provided algorithm.
+/// The signature data will be filled later when building the signed data.
+fn build_signature_headers(alg: iana::Algorithm) -> CoseSignature {
+    let protected = HeaderBuilder::new().algorithm(alg).build();
+    CoseSignatureBuilder::new().protected(protected).build()
+}
+
+fn ecdsa_sign(message: &[u8], key: &EcKeyRef<Private>) -> Result<Vec<u8>> {
+    let digest = sha256(message);
+    // Passes the digest to `ECDSA_do_sign` as recommended in the spec:
+    // https://commondatastorage.googleapis.com/chromium-boringssl-docs/ecdsa.h.html#ECDSA_do_sign
+    let sig = EcdsaSig::sign::<Private>(&digest, key)?;
+    Ok(sig.to_der()?)
+}
+
+fn get_affine_coordinates(key: &EcKeyRef<Private>) -> Result<(Vec<u8>, Vec<u8>)> {
+    let mut ctx = BigNumContext::new()?;
+    let mut x = BigNum::new()?;
+    let mut y = BigNum::new()?;
+    key.public_key().affine_coordinates_gfp(key.group(), &mut x, &mut y, &mut ctx)?;
+    let x = x.to_vec_padded(ATTESTATION_KEY_AFFINE_COORDINATE_SIZE)?;
+    let y = y.to_vec_padded(ATTESTATION_KEY_AFFINE_COORDINATE_SIZE)?;
+    Ok((x, y))
+}
+
+fn to_cose_public_key(key: &EcKeyRef<Private>) -> Result<CoseKey> {
+    let (x, y) = get_affine_coordinates(key)?;
+    Ok(CoseKeyBuilder::new_ec2_pub_key(ATTESTATION_KEY_CURVE, x, y)
+        .algorithm(ATTESTATION_KEY_ALGO)
+        .build())
+}
+
 impl Interface for VmPayloadService {}
 
 impl VmPayloadService {
@@ -116,3 +237,106 @@
     });
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use anyhow::bail;
+    use ciborium::Value;
+    use coset::{iana::EnumI64, Label};
+    use hwtrust::{dice, session::Session};
+    use openssl::pkey::Public;
+
+    /// The following data is generated randomly with urandom.
+    const CHALLENGE: [u8; 16] = [
+        0xb3, 0x66, 0xfa, 0x72, 0x92, 0x32, 0x2c, 0xd4, 0x99, 0xcb, 0x00, 0x1f, 0x0e, 0xe0, 0xc7,
+        0x41,
+    ];
+
+    #[test]
+    fn csr_and_private_key_have_correct_format() -> Result<()> {
+        let dice_artifacts = diced_sample_inputs::make_sample_bcc_and_cdis()?;
+
+        let (private_key, csr) = generate_attestation_key_and_csr(&CHALLENGE, &dice_artifacts)?;
+        let ec_private_key = EcKey::private_key_from_der(&private_key)?;
+        let csr = Csr::from_cbor_slice(&csr).unwrap();
+        let cose_sign = CoseSign::from_slice(&csr.signed_csr_payload).unwrap();
+        let aad = &[];
+
+        // Checks CSR payload.
+        let csr_payload =
+            cose_sign.payload.as_ref().and_then(|v| CsrPayload::from_cbor_slice(v).ok()).unwrap();
+        let public_key = to_cose_public_key(&ec_private_key)?.to_vec().unwrap();
+        let expected_csr_payload = CsrPayload { challenge: CHALLENGE.to_vec(), public_key };
+        assert_eq!(expected_csr_payload, csr_payload);
+
+        // Checks the first signature is signed with CDI_Leaf_Priv.
+        let session = Session::default();
+        let chain = dice::Chain::from_cbor(&session, &csr.dice_cert_chain)?;
+        let public_key = chain.leaf().subject_public_key();
+        cose_sign
+            .verify_signature(0, aad, |signature, message| public_key.verify(signature, message))?;
+
+        // Checks the second signature is signed with attestation key.
+        let attestation_public_key = CoseKey::from_slice(&csr_payload.public_key).unwrap();
+        let ec_public_key = to_ec_public_key(&attestation_public_key)?;
+        cose_sign.verify_signature(1, aad, |signature, message| {
+            ecdsa_verify(signature, message, &ec_public_key)
+        })?;
+
+        // Verifies that private key and the public key form a valid key pair.
+        let message = b"test message";
+        let signature = ecdsa_sign(message, &ec_private_key)?;
+        ecdsa_verify(&signature, message, &ec_public_key)?;
+
+        Ok(())
+    }
+
+    fn ecdsa_verify(
+        signature: &[u8],
+        message: &[u8],
+        ec_public_key: &EcKeyRef<Public>,
+    ) -> Result<()> {
+        let sig = EcdsaSig::from_der(signature)?;
+        let digest = sha256(message);
+        if sig.verify(&digest, ec_public_key)? {
+            Ok(())
+        } else {
+            bail!("Signature does not match")
+        }
+    }
+
+    fn to_ec_public_key(cose_key: &CoseKey) -> Result<EcKey<Public>> {
+        check_ec_key_params(cose_key)?;
+        let group = EcGroup::from_curve_name(ATTESTATION_KEY_NID)?;
+        let x = get_label_value_as_bignum(cose_key, Label::Int(iana::Ec2KeyParameter::X.to_i64()))?;
+        let y = get_label_value_as_bignum(cose_key, Label::Int(iana::Ec2KeyParameter::Y.to_i64()))?;
+        let key = EcKey::from_public_key_affine_coordinates(&group, &x, &y)?;
+        key.check_key()?;
+        Ok(key)
+    }
+
+    fn check_ec_key_params(cose_key: &CoseKey) -> Result<()> {
+        assert_eq!(coset::KeyType::Assigned(iana::KeyType::EC2), cose_key.kty);
+        assert_eq!(Some(coset::Algorithm::Assigned(ATTESTATION_KEY_ALGO)), cose_key.alg);
+        let crv = get_label_value(cose_key, Label::Int(iana::Ec2KeyParameter::Crv.to_i64()))?;
+        assert_eq!(&Value::from(ATTESTATION_KEY_CURVE.to_i64()), crv);
+        Ok(())
+    }
+
+    fn get_label_value_as_bignum(key: &CoseKey, label: Label) -> Result<BigNum> {
+        get_label_value(key, label)?
+            .as_bytes()
+            .map(|v| BigNum::from_slice(&v[..]).unwrap())
+            .ok_or_else(|| anyhow!("Value not a bstr."))
+    }
+
+    fn get_label_value(key: &CoseKey, label: Label) -> Result<&Value> {
+        Ok(&key
+            .params
+            .iter()
+            .find(|(k, _)| k == &label)
+            .ok_or_else(|| anyhow!("Label {:?} not found", label))?
+            .1)
+    }
+}