diff --git a/keystore2/Android.bp b/keystore2/Android.bp
index e6cb4fb..43419b7 100644
--- a/keystore2/Android.bp
+++ b/keystore2/Android.bp
@@ -89,6 +89,8 @@
         "librand",
         "libserde",
         "libserde_cbor",
+	"libthiserror",
+	"libanyhow",
     ],
 }
 
@@ -122,6 +124,8 @@
         "librand",
         "libserde",
         "libserde_cbor",
+	"libthiserror",
+	"libanyhow",
     ],
 }
 
diff --git a/keystore2/test_utils/authorizations.rs b/keystore2/test_utils/authorizations.rs
index 4fbe124..d5a7b7b 100644
--- a/keystore2/test_utils/authorizations.rs
+++ b/keystore2/test_utils/authorizations.rs
@@ -22,6 +22,7 @@
 };
 
 /// Helper struct to create set of Authorizations.
+#[derive(Debug, Clone, Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub struct AuthSetBuilder(Vec<KeyParameter>);
 
 impl Default for AuthSetBuilder {
@@ -77,6 +78,15 @@
         });
         self
     }
+
+    /// Add No_auth_required.
+    pub fn no_auth_required(mut self) -> Self {
+        self.0.push(KeyParameter {
+            tag: Tag::NO_AUTH_REQUIRED,
+            value: KeyParameterValue::BoolValue(true),
+        });
+        self
+    }
 }
 
 impl Deref for AuthSetBuilder {
diff --git a/keystore2/test_utils/key_generations.rs b/keystore2/test_utils/key_generations.rs
index f49aa9f..d917fa1 100644
--- a/keystore2/test_utils/key_generations.rs
+++ b/keystore2/test_utils/key_generations.rs
@@ -14,43 +14,94 @@
 
 //! This module implements test utils to generate various types of keys.
 
+use anyhow::Result;
+
 use android_hardware_security_keymint::aidl::android::hardware::security::keymint::{
-    Algorithm::Algorithm, Digest::Digest, EcCurve::EcCurve, KeyPurpose::KeyPurpose,
+    Algorithm::Algorithm, Digest::Digest, EcCurve::EcCurve, ErrorCode::ErrorCode,
+    KeyPurpose::KeyPurpose,
 };
 use android_system_keystore2::aidl::android::system::keystore2::{
     Domain::Domain, IKeystoreSecurityLevel::IKeystoreSecurityLevel, KeyDescriptor::KeyDescriptor,
-    KeyMetadata::KeyMetadata,
+    KeyMetadata::KeyMetadata, ResponseCode::ResponseCode,
 };
 
 use crate::authorizations::AuthSetBuilder;
+use android_system_keystore2::binder::{ExceptionCode, Result as BinderResult};
 
-const SELINUX_SHELL_NAMESPACE: i64 = 1;
+/// Shell namespace.
+pub const SELINUX_SHELL_NAMESPACE: i64 = 1;
 
-/// Generate attested EC Key blob using given security level with below key parameters -
+/// To map Keystore errors.
+#[derive(thiserror::Error, Debug, Eq, PartialEq)]
+pub enum Error {
+    /// Keystore2 error code
+    #[error("ResponseCode {0:?}")]
+    Rc(ResponseCode),
+    /// Keymint error code
+    #[error("ErrorCode {0:?}")]
+    Km(ErrorCode),
+    /// Exception
+    #[error("Binder exception {0:?}")]
+    Binder(ExceptionCode),
+}
+
+/// Keystore2 error mapping.
+pub fn map_ks_error<T>(r: BinderResult<T>) -> Result<T, Error> {
+    r.map_err(|s| {
+        match s.exception_code() {
+            ExceptionCode::SERVICE_SPECIFIC => {
+                match s.service_specific_error() {
+                    se if se < 0 => {
+                        // Negative service specific errors are KM error codes.
+                        Error::Km(ErrorCode(se))
+                    }
+                    se => {
+                        // Positive service specific errors are KS response codes.
+                        Error::Rc(ResponseCode(se))
+                    }
+                }
+            }
+            // We create `Error::Binder` to preserve the exception code
+            // for logging.
+            e_code => Error::Binder(e_code),
+        }
+    })
+}
+
+/// Generate EC Key using given security level and domain with below key parameters and
+/// optionally allow the generated key to be attested with factory provisioned attest key using
+/// given challenge and application id -
 ///     Purposes: SIGN and VERIFY
 ///     Digest: SHA_2_256
 ///     Curve: P_256
-pub fn generate_ec_p256_signing_key_with_attestation(
+pub fn generate_ec_p256_signing_key(
     sec_level: &binder::Strong<dyn IKeystoreSecurityLevel>,
+    domain: Domain,
+    nspace: i64,
+    alias: Option<String>,
+    att_challenge: Option<&[u8]>,
+    att_app_id: Option<&[u8]>,
 ) -> binder::Result<KeyMetadata> {
-    let att_challenge: &[u8] = b"foo";
-    let att_app_id: &[u8] = b"bar";
-    let gen_params = AuthSetBuilder::new()
+    let mut key_attest = false;
+    let mut gen_params = AuthSetBuilder::new()
         .algorithm(Algorithm::EC)
         .purpose(KeyPurpose::SIGN)
         .purpose(KeyPurpose::VERIFY)
         .digest(Digest::SHA_2_256)
-        .ec_curve(EcCurve::P_256)
-        .attestation_challenge(att_challenge.to_vec())
-        .attestation_app_id(att_app_id.to_vec());
+        .ec_curve(EcCurve::P_256);
+
+    if let Some(challenge) = att_challenge {
+        key_attest = true;
+        gen_params = gen_params.clone().attestation_challenge(challenge.to_vec());
+    }
+
+    if let Some(app_id) = att_app_id {
+        key_attest = true;
+        gen_params = gen_params.clone().attestation_app_id(app_id.to_vec());
+    }
 
     match sec_level.generateKey(
-        &KeyDescriptor {
-            domain: Domain::BLOB,
-            nspace: SELINUX_SHELL_NAMESPACE,
-            alias: None,
-            blob: None,
-        },
+        &KeyDescriptor { domain, nspace, alias, blob: None },
         None,
         &gen_params,
         0,
@@ -58,8 +109,12 @@
     ) {
         Ok(key_metadata) => {
             assert!(key_metadata.certificate.is_some());
-            assert!(key_metadata.certificateChain.is_some());
-            assert!(key_metadata.key.blob.is_some());
+            if key_attest {
+                assert!(key_metadata.certificateChain.is_some());
+            }
+            if domain == Domain::BLOB {
+                assert!(key_metadata.key.blob.is_some());
+            }
 
             Ok(key_metadata)
         }
diff --git a/keystore2/tests/Android.bp b/keystore2/tests/Android.bp
new file mode 100644
index 0000000..21784a1
--- /dev/null
+++ b/keystore2/tests/Android.bp
@@ -0,0 +1,39 @@
+// Copyright 2022, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+rust_test {
+    name: "keystore2_client_tests",
+    defaults: [
+        "keymint_use_latest_hal_aidl_rust",
+        "keystore2_use_latest_aidl_rust",
+    ],
+    srcs: ["keystore2_client_tests.rs"],
+    test_suites: [
+        "general-tests",
+    ],
+    test_config: "AndroidTest.xml",
+
+    rustlibs: [
+        "librustutils",
+        "libkeystore2_test_utils",
+        "libnix",
+        "libanyhow",
+        "libbinder_rs",
+        "liblazy_static",
+        "liblibc",
+        "libserde",
+        "libthiserror",
+    ],
+    require_root: true,
+}
diff --git a/keystore2/tests/AndroidTest.xml b/keystore2/tests/AndroidTest.xml
new file mode 100644
index 0000000..7db36f7
--- /dev/null
+++ b/keystore2/tests/AndroidTest.xml
@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2022 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<configuration description="Config to run keystore2_client_tests device tests.">
+
+    <target_preparer class="com.android.tradefed.targetprep.RootTargetPreparer">
+    </target_preparer>
+
+    <target_preparer class="com.android.tradefed.targetprep.PushFilePreparer">
+        <option name="cleanup" value="true" />
+        <option
+            name="push"
+            value="keystore2_client_tests->/data/local/tmp/keystore2_client_tests"
+        />
+    </target_preparer>
+
+    <test class="com.android.tradefed.testtype.rust.RustBinaryTest" >
+        <option name="test-device-path" value="/data/local/tmp" />
+        <option name="module-name" value="keystore2_client_tests" />
+        <!-- When we run run multiple tests by default they run in parallel.
+          This will create issue as we create various child/user contexts
+          in a test leading to issues with IPC.
+          Serializing tests with below configuration to avoid IPC issues.
+        -->
+        <option name="native-test-flag" value="--test-threads=1" />
+    </test>
+</configuration>
diff --git a/keystore2/tests/keystore2_client_tests.rs b/keystore2/tests/keystore2_client_tests.rs
new file mode 100644
index 0000000..246f204
--- /dev/null
+++ b/keystore2/tests/keystore2_client_tests.rs
@@ -0,0 +1,140 @@
+// Copyright 2022, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use nix::unistd::{getuid, Gid, Uid};
+use rustutils::users::AID_USER_OFFSET;
+use serde::{Deserialize, Serialize};
+
+use android_hardware_security_keymint::aidl::android::hardware::security::keymint::{
+    Digest::Digest, KeyPurpose::KeyPurpose, SecurityLevel::SecurityLevel,
+};
+use android_system_keystore2::aidl::android::system::keystore2::{
+    Domain::Domain, ResponseCode::ResponseCode,
+};
+
+use keystore2_test_utils::authorizations;
+use keystore2_test_utils::get_keystore_service;
+use keystore2_test_utils::key_generations;
+use keystore2_test_utils::run_as;
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+enum TestOutcome {
+    Ok,
+    BackendBusy,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+struct BarrierReached;
+
+fn create_op_run_as_child(
+    target_ctx: &'static str,
+    auid: Uid,
+    agid: Gid,
+    forced_op: bool,
+) -> run_as::ChildHandle<TestOutcome, BarrierReached> {
+    unsafe {
+        run_as::run_as_child(target_ctx, auid, agid, move |reader, writer| {
+            let keystore2 = get_keystore_service();
+            let sec_level = keystore2.getSecurityLevel(SecurityLevel::TRUSTED_ENVIRONMENT).unwrap();
+            let alias = format!("ks_prune_op_test_key_{}", getuid());
+            let key_metadata = key_generations::generate_ec_p256_signing_key(
+                &sec_level,
+                Domain::APP,
+                key_generations::SELINUX_SHELL_NAMESPACE,
+                Some(alias),
+                None,
+                None,
+            )
+            .unwrap();
+
+            let result = sec_level.createOperation(
+                &key_metadata.key,
+                &authorizations::AuthSetBuilder::new()
+                    .purpose(KeyPurpose::SIGN)
+                    .digest(Digest::SHA_2_256),
+                forced_op,
+            );
+
+            // At this point the result must be `BACKEND_BUSY` or `Ok`.
+            let outcome = match &result {
+                Ok(_) => TestOutcome::Ok,
+                Err(s) if s.service_specific_error() == ResponseCode::BACKEND_BUSY.0 => {
+                    TestOutcome::BackendBusy
+                }
+                Err(e) => panic!("createOperation returned unexpected err: {:?}", e),
+            };
+
+            // Let the parent know that an operation has been started, then
+            // wait until the parent notifies us to continue, so the operation
+            // remains open.
+            writer.send(&BarrierReached {});
+            reader.recv();
+
+            outcome
+        })
+        .expect("Failed to create child proc.")
+    }
+}
+
+fn create_operations(
+    target_ctx: &'static str,
+    forced_op: bool,
+    max_ops: i32,
+) -> Vec<run_as::ChildHandle<TestOutcome, BarrierReached>> {
+    let base_gid = 99 * AID_USER_OFFSET + 10001;
+    let base_uid = 99 * AID_USER_OFFSET + 10001;
+    (0..max_ops)
+        .into_iter()
+        .map(|i| {
+            create_op_run_as_child(
+                target_ctx,
+                Uid::from_raw(base_uid + (i as u32)),
+                Gid::from_raw(base_gid + (i as u32)),
+                forced_op,
+            )
+        })
+        .collect()
+}
+
+/// This test verifies that backend service throws BACKEND_BUSY error when all
+/// operations slots are full. This test creates operations in child processes and
+/// collects the status of operations performed in each child proc and determines
+/// whether any child proc exited with error status.
+#[test]
+fn keystore2_backend_busy_test() {
+    const MAX_OPS: i32 = 100;
+    static TARGET_CTX: &str = "u:r:untrusted_app:s0:c91,c256,c10,c20";
+    let forced_op = false;
+
+    let mut child_handles = create_operations(TARGET_CTX, forced_op, MAX_OPS);
+
+    // Wait until all child procs notifies us to continue,
+    // so that there are definitely enough operations outstanding to trigger a BACKEND_BUSY.
+    for ch in child_handles.iter_mut() {
+        ch.recv();
+    }
+    // Notify each child to resume and finish.
+    for ch in child_handles.iter_mut() {
+        ch.send(&BarrierReached {});
+    }
+
+    // Collect the result and validate whether backend busy has occurred.
+    let mut busy_count = 0;
+    for ch in child_handles.into_iter() {
+        if ch.get_result() == TestOutcome::BackendBusy {
+            busy_count += 1;
+        }
+    }
+    assert!(busy_count > 0)
+}
diff --git a/keystore2/tests/legacy_blobs/keystore2_legacy_blob_tests.rs b/keystore2/tests/legacy_blobs/keystore2_legacy_blob_tests.rs
index cf9f1a9..48275ae 100644
--- a/keystore2/tests/legacy_blobs/keystore2_legacy_blob_tests.rs
+++ b/keystore2/tests/legacy_blobs/keystore2_legacy_blob_tests.rs
@@ -164,9 +164,17 @@
                 .getSecurityLevel(SecurityLevel::SecurityLevel::TRUSTED_ENVIRONMENT)
                 .unwrap();
             // Generate Key BLOB and prepare legacy keystore blob files.
-            let key_metadata =
-                key_generations::generate_ec_p256_signing_key_with_attestation(&sec_level)
-                    .expect("Failed to generate key blob");
+            let att_challenge: &[u8] = b"foo";
+            let att_app_id: &[u8] = b"bar";
+            let key_metadata = key_generations::generate_ec_p256_signing_key(
+                &sec_level,
+                Domain::BLOB,
+                SELINUX_SHELL_NAMESPACE,
+                None,
+                Some(att_challenge),
+                Some(att_app_id),
+            )
+            .expect("Failed to generate key blob");
 
             // Create keystore file layout for user_99.
             let pw: Password = PASSWORD.into();
@@ -415,9 +423,17 @@
                 .getSecurityLevel(SecurityLevel::SecurityLevel::TRUSTED_ENVIRONMENT)
                 .unwrap();
             // Generate Key BLOB and prepare legacy keystore blob files.
-            let key_metadata =
-                key_generations::generate_ec_p256_signing_key_with_attestation(&sec_level)
-                    .expect("Failed to generate key blob");
+            let att_challenge: &[u8] = b"foo";
+            let att_app_id: &[u8] = b"bar";
+            let key_metadata = key_generations::generate_ec_p256_signing_key(
+                &sec_level,
+                Domain::BLOB,
+                SELINUX_SHELL_NAMESPACE,
+                None,
+                Some(att_challenge),
+                Some(att_app_id),
+            )
+            .expect("Failed to generate key blob");
 
             // Create keystore file layout for user_98.
             let pw: Password = PASSWORD.into();