diff --git a/OWNERS b/OWNERS
index 03e5769..6fdb550 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1,5 +1,4 @@
 alanstokes@google.com
-cbrubaker@google.com
 drysdale@google.com
 eranm@google.com
 hasinitg@google.com
@@ -8,4 +7,5 @@
 kroot@google.com
 sethmo@google.com
 swillden@google.com
+trong@google.com
 zeuthen@google.com
diff --git a/keystore/keystore_attestation_id.cpp b/keystore/keystore_attestation_id.cpp
index ccd3808..75c62dd 100644
--- a/keystore/keystore_attestation_id.cpp
+++ b/keystore/keystore_attestation_id.cpp
@@ -74,8 +74,8 @@
 }
 
 KeyAttestationApplicationIdProvider::KeyAttestationApplicationIdProvider()
-    : BpKeyAttestationApplicationIdProvider(
-          android::defaultServiceManager()->getService(String16("sec_key_att_app_id_provider"))) {}
+    : BpKeyAttestationApplicationIdProvider(android::defaultServiceManager()->waitForService(
+          String16("sec_key_att_app_id_provider"))) {}
 
 DECLARE_STACK_OF(ASN1_OCTET_STRING);
 
diff --git a/keystore2/src/enforcements.rs b/keystore2/src/enforcements.rs
index 8d5e985..3bf582f 100644
--- a/keystore2/src/enforcements.rs
+++ b/keystore2/src/enforcements.rs
@@ -51,9 +51,9 @@
     /// An outstanding per operation authorization request.
     OpAuth,
     /// An outstanding request for per operation authorization and secure timestamp.
-    TimeStampedOpAuth(Receiver<Result<TimeStampToken, Error>>),
+    TimeStampedOpAuth(Mutex<Receiver<Result<TimeStampToken, Error>>>),
     /// An outstanding request for a timestamp token.
-    TimeStamp(Receiver<Result<TimeStampToken, Error>>),
+    TimeStamp(Mutex<Receiver<Result<TimeStampToken, Error>>>),
 }
 
 #[derive(Debug)]
@@ -64,8 +64,6 @@
     hat: Mutex<Option<HardwareAuthToken>>,
 }
 
-unsafe impl Sync for AuthRequest {}
-
 impl AuthRequest {
     fn op_auth() -> Arc<Self> {
         Arc::new(Self { state: AuthRequestState::OpAuth, hat: Mutex::new(None) })
@@ -73,7 +71,7 @@
 
     fn timestamped_op_auth(receiver: Receiver<Result<TimeStampToken, Error>>) -> Arc<Self> {
         Arc::new(Self {
-            state: AuthRequestState::TimeStampedOpAuth(receiver),
+            state: AuthRequestState::TimeStampedOpAuth(Mutex::new(receiver)),
             hat: Mutex::new(None),
         })
     }
@@ -82,7 +80,10 @@
         hat: HardwareAuthToken,
         receiver: Receiver<Result<TimeStampToken, Error>>,
     ) -> Arc<Self> {
-        Arc::new(Self { state: AuthRequestState::TimeStamp(receiver), hat: Mutex::new(Some(hat)) })
+        Arc::new(Self {
+            state: AuthRequestState::TimeStamp(Mutex::new(receiver)),
+            hat: Mutex::new(Some(hat)),
+        })
     }
 
     fn add_auth_token(&self, hat: HardwareAuthToken) {
@@ -100,7 +101,11 @@
 
         let tst = match &self.state {
             AuthRequestState::TimeStampedOpAuth(recv) | AuthRequestState::TimeStamp(recv) => {
-                let result = recv.recv().context("In get_auth_tokens: Sender disconnected.")?;
+                let result = recv
+                    .lock()
+                    .unwrap()
+                    .recv()
+                    .context("In get_auth_tokens: Sender disconnected.")?;
                 Some(result.context(ks_err!(
                     "Worker responded with error \
                     from generating timestamp token.",
diff --git a/prng_seeder/src/cutils_socket.rs b/prng_seeder/src/cutils_socket.rs
index ab2c869..b408be6 100644
--- a/prng_seeder/src/cutils_socket.rs
+++ b/prng_seeder/src/cutils_socket.rs
@@ -19,7 +19,11 @@
 
 pub fn android_get_control_socket(name: &str) -> Result<UnixListener> {
     let name = CString::new(name)?;
+    // SAFETY: name is a valid C string, and android_get_control_socket doesn't retain it after it
+    // returns.
     let fd = unsafe { cutils_socket_bindgen::android_get_control_socket(name.as_ptr()) };
     ensure!(fd >= 0, "android_get_control_socket failed");
+    // SAFETY: android_get_control_socket either returns a valid and open FD or -1, and we checked
+    // that it's not -1.
     Ok(unsafe { UnixListener::from_raw_fd(fd) })
 }
diff --git a/prng_seeder/src/drbg.rs b/prng_seeder/src/drbg.rs
index 89c5a88..808ea18 100644
--- a/prng_seeder/src/drbg.rs
+++ b/prng_seeder/src/drbg.rs
@@ -23,6 +23,9 @@
 
 impl Drbg {
     pub fn new(entropy: &Entropy) -> Result<Drbg> {
+        // SAFETY: entropy must be a valid pointer because it comes from a reference, and a null
+        // pointer is allowed for personalization. CTR_DRBG_new doesn't retain the entropy pointer
+        // for use after it returns.
         let p = unsafe { bssl_sys::CTR_DRBG_new(entropy.as_ptr(), std::ptr::null(), 0) };
         ensure!(!p.is_null(), "CTR_DRBG_new failed");
         Ok(Drbg(p))
@@ -30,6 +33,9 @@
 
     pub fn reseed(&mut self, entropy: &Entropy) -> Result<()> {
         ensure!(
+            // SAFETY: We know that self.0 is valid because it was initialised from CTR_DRBG_new in
+            // Drbg::new above. The entropy pointer must be valid because it comes from a reference,
+            // and CTR_DRBG_reseed doesn't retain it after it returns.
             unsafe { bssl_sys::CTR_DRBG_reseed(self.0, entropy.as_ptr(), std::ptr::null(), 0) }
                 == 1,
             "CTR_DRBG_reseed failed"
@@ -39,6 +45,10 @@
 
     pub fn generate(&mut self, buf: &mut [u8]) -> Result<()> {
         ensure!(
+            // SAFETY: We know that self.0 is valid because it was initialised from CTR_DRBG_new in
+            // Drbg::new above. The out pointer and length must be valid and unaliased because they
+            // come from a mutable slice reference, and CTR_DRBG_generate doesn't retain them after
+            // it returns.
             unsafe {
                 bssl_sys::CTR_DRBG_generate(
                     self.0,
@@ -56,10 +66,13 @@
 
 impl Drop for Drbg {
     fn drop(&mut self) {
+        // SAFETY: We know that self.0 is valid because it was initialised from CTR_DRBG_new in
+        // Drbg::new above, and this is the only place that frees it.
         unsafe {
             bssl_sys::CTR_DRBG_free(self.0);
         }
     }
 }
 
+// SAFETY: CTR_DRBG functions can be called from any thread.
 unsafe impl Send for Drbg {}
diff --git a/prng_seeder/src/main.rs b/prng_seeder/src/main.rs
index 924481a..f8b0c63 100644
--- a/prng_seeder/src/main.rs
+++ b/prng_seeder/src/main.rs
@@ -70,6 +70,7 @@
 fn setup() -> Result<(ConditionerBuilder, UnixListener)> {
     configure_logging()?;
     let cli = Cli::try_parse()?;
+    // SAFETY: Nothing else sets the signal handler, so either it was set here or it is the default.
     unsafe { signal::signal(signal::Signal::SIGPIPE, signal::SigHandler::SigIgn) }
         .context("In setup, setting SIGPIPE to SIG_IGN")?;