Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 1325 insertions, 0 deletions

diff --git a/security/manager/ssl/rsclientcerts/src/error.rs b/security/manager/ssl/rsclientcerts/src/error.rs
new file mode 100644
index 0000000000..6ef9062d32
--- /dev/null
+++ b/security/manager/ssl/rsclientcerts/src/error.rs
@@ -0,0 +1,103 @@
+/* -*- Mode: rust; rust-indent-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use std::fmt;
+
+/// Helper macro to create an Error that knows which file and line it occurred
+/// on. Can optionally have some extra information as a String.
+#[macro_export]
+macro_rules! error_here {
+    ($error_type:expr) => {
+        Error::new($error_type, file!(), line!(), None)
+    };
+    ($error_type:expr, $info:expr) => {
+        Error::new($error_type, file!(), line!(), Some($info))
+    };
+}
+
+/// Error type for identifying errors in this crate. Use the error_here! macro
+/// to instantiate.
+#[derive(Debug)]
+pub struct Error {
+    typ: ErrorType,
+    file: &'static str,
+    line: u32,
+    info: Option<String>,
+}
+
+impl Error {
+    pub fn new(typ: ErrorType, file: &'static str, line: u32, info: Option<String>) -> Error {
+        Error {
+            typ,
+            file,
+            line,
+            info,
+        }
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if let Some(info) = &self.info {
+            write!(f, "{} at {}:{} ({})", self.typ, self.file, self.line, info)
+        } else {
+            write!(f, "{} at {}:{}", self.typ, self.file, self.line)
+        }
+    }
+}
+
+impl Clone for Error {
+    fn clone(&self) -> Self {
+        Error {
+            typ: self.typ,
+            file: self.file,
+            line: self.line,
+            info: self.info.as_ref().cloned(),
+        }
+    }
+
+    fn clone_from(&mut self, source: &Self) {
+        self.typ = source.typ;
+        self.file = source.file;
+        self.line = source.line;
+        self.info = source.info.as_ref().cloned();
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+pub enum ErrorType {
+    /// An error in an external library or resource.
+    ExternalError,
+    /// Unexpected extra input (e.g. in an ASN.1 encoding).
+    ExtraInput,
+    /// Invalid argument.
+    InvalidArgument,
+    /// Invalid data input.
+    InvalidInput,
+    /// An internal library failure (e.g. an expected invariant failed).
+    LibraryFailure,
+    /// Truncated input (e.g. in an ASN.1 encoding).
+    TruncatedInput,
+    /// Unsupported input.
+    UnsupportedInput,
+    /// A given value could not be represented in the type used for it.
+    ValueTooLarge,
+}
+
+impl fmt::Display for ErrorType {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let error_type_str = match self {
+            ErrorType::ExternalError => "ExternalError",
+            ErrorType::ExtraInput => "ExtraInput",
+            ErrorType::InvalidArgument => "InvalidArgument",
+            ErrorType::InvalidInput => "InvalidInput",
+            ErrorType::LibraryFailure => "LibraryFailure",
+            ErrorType::TruncatedInput => "TruncatedInput",
+            ErrorType::UnsupportedInput => "UnsupportedInput",
+            ErrorType::ValueTooLarge => "ValueTooLarge",
+        };
+        write!(f, "{}", error_type_str)
+    }
+}
diff --git a/security/manager/ssl/rsclientcerts/src/lib.rs b/security/manager/ssl/rsclientcerts/src/lib.rs
new file mode 100644
index 0000000000..01fa31e204
--- /dev/null
+++ b/security/manager/ssl/rsclientcerts/src/lib.rs
@@ -0,0 +1,11 @@
+/* -*- Mode: rust; rust-indent-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+extern crate byteorder;
+extern crate pkcs11_bindings;
+
+pub mod error;
+pub mod manager;
+pub mod util;
diff --git a/security/manager/ssl/rsclientcerts/src/manager.rs b/security/manager/ssl/rsclientcerts/src/manager.rs
new file mode 100644
index 0000000000..507bed3a83
--- /dev/null
+++ b/security/manager/ssl/rsclientcerts/src/manager.rs
@@ -0,0 +1,671 @@
+/* -*- Mode: rust; rust-indent-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use pkcs11_bindings::*;
+use std::collections::{BTreeMap, BTreeSet};
+use std::sync::mpsc::{channel, Receiver, Sender};
+use std::thread;
+use std::thread::JoinHandle;
+use std::time::{Duration, Instant};
+
+use crate::error::{Error, ErrorType};
+use crate::error_here;
+use crate::util::*;
+
+/// Helper enum to differentiate between sessions on the modern slot and sessions on the legacy
+/// slot. The former is for EC keys and RSA keys that can be used with RSA-PSS whereas the latter is
+/// for RSA keys that cannot be used with RSA-PSS.
+#[derive(Clone, Copy, PartialEq)]
+pub enum SlotType {
+    Modern,
+    Legacy,
+}
+
+pub trait CryptokiObject {
+    fn matches(&self, slot_type: SlotType, attrs: &[(CK_ATTRIBUTE_TYPE, Vec<u8>)]) -> bool;
+    fn get_attribute(&self, attribute: CK_ATTRIBUTE_TYPE) -> Option<&[u8]>;
+}
+
+pub trait Sign {
+    fn get_signature_length(
+        &mut self,
+        data: &[u8],
+        params: &Option<CK_RSA_PKCS_PSS_PARAMS>,
+    ) -> Result<usize, Error>;
+    fn sign(
+        &mut self,
+        data: &[u8],
+        params: &Option<CK_RSA_PKCS_PSS_PARAMS>,
+    ) -> Result<Vec<u8>, Error>;
+}
+
+pub trait ClientCertsBackend {
+    type Cert: CryptokiObject;
+    type Key: CryptokiObject + Sign;
+
+    #[allow(clippy::type_complexity)]
+    fn find_objects(&self) -> Result<(Vec<Self::Cert>, Vec<Self::Key>), Error>;
+}
+
+/// Helper type for sending `ManagerArguments` to the real `Manager`.
+type ManagerArgumentsSender = Sender<ManagerArguments>;
+/// Helper type for receiving `ManagerReturnValue`s from the real `Manager`.
+type ManagerReturnValueReceiver = Receiver<ManagerReturnValue>;
+
+/// Helper enum that encapsulates arguments to send from the `ManagerProxy` to the real `Manager`.
+/// `ManagerArguments::Stop` is a special variant that stops the background thread and drops the
+/// `Manager`.
+enum ManagerArguments {
+    OpenSession(SlotType),
+    CloseSession(CK_SESSION_HANDLE),
+    CloseAllSessions(SlotType),
+    StartSearch(CK_SESSION_HANDLE, Vec<(CK_ATTRIBUTE_TYPE, Vec<u8>)>),
+    Search(CK_SESSION_HANDLE, usize),
+    ClearSearch(CK_SESSION_HANDLE),
+    GetAttributes(CK_OBJECT_HANDLE, Vec<CK_ATTRIBUTE_TYPE>),
+    StartSign(
+        CK_SESSION_HANDLE,
+        CK_OBJECT_HANDLE,
+        Option<CK_RSA_PKCS_PSS_PARAMS>,
+    ),
+    GetSignatureLength(CK_SESSION_HANDLE, Vec<u8>),
+    Sign(CK_SESSION_HANDLE, Vec<u8>),
+    Stop,
+}
+
+/// Helper enum that encapsulates return values from the real `Manager` that are sent back to the
+/// `ManagerProxy`. `ManagerReturnValue::Stop` is a special variant that indicates that the
+/// `Manager` will stop.
+enum ManagerReturnValue {
+    OpenSession(Result<CK_SESSION_HANDLE, Error>),
+    CloseSession(Result<(), Error>),
+    CloseAllSessions(Result<(), Error>),
+    StartSearch(Result<(), Error>),
+    Search(Result<Vec<CK_OBJECT_HANDLE>, Error>),
+    ClearSearch(Result<(), Error>),
+    GetAttributes(Result<Vec<Option<Vec<u8>>>, Error>),
+    StartSign(Result<(), Error>),
+    GetSignatureLength(Result<usize, Error>),
+    Sign(Result<Vec<u8>, Error>),
+    Stop(Result<(), Error>),
+}
+
+/// Helper macro to implement the body of each public `ManagerProxy` function. Takes a
+/// `ManagerProxy` instance (should always be `self`), a `ManagerArguments` representing the
+/// `Manager` function to call and the arguments to use, and the qualified type of the expected
+/// `ManagerReturnValue` that will be received from the `Manager` when it is done.
+macro_rules! manager_proxy_fn_impl {
+    ($manager:ident, $argument_enum:expr, $return_type:path) => {
+        match $manager.proxy_call($argument_enum) {
+            Ok($return_type(result)) => result,
+            Ok(_) => Err(error_here!(ErrorType::LibraryFailure)),
+            Err(e) => Err(e),
+        }
+    };
+}
+
+/// `ManagerProxy` synchronously proxies calls from any thread to the `Manager` that runs on a
+/// single thread. This is necessary because the underlying OS APIs in use are not guaranteed to be
+/// thread-safe (e.g. they may use thread-local storage). Using it should be identical to using the
+/// real `Manager`.
+pub struct ManagerProxy {
+    sender: ManagerArgumentsSender,
+    receiver: ManagerReturnValueReceiver,
+    thread_handle: Option<JoinHandle<()>>,
+}
+
+impl ManagerProxy {
+    pub fn new<B: ClientCertsBackend + Send + 'static>(backend: B) -> Result<ManagerProxy, Error> {
+        let (proxy_sender, manager_receiver) = channel();
+        let (manager_sender, proxy_receiver) = channel();
+        let thread_handle = thread::Builder::new()
+            .name("osclientcert".into())
+            .spawn(move || {
+                let mut real_manager = Manager::new(backend);
+                while let Ok(arguments) = manager_receiver.recv() {
+                    let results = match arguments {
+                        ManagerArguments::OpenSession(slot_type) => {
+                            ManagerReturnValue::OpenSession(real_manager.open_session(slot_type))
+                        }
+                        ManagerArguments::CloseSession(session_handle) => {
+                            ManagerReturnValue::CloseSession(
+                                real_manager.close_session(session_handle),
+                            )
+                        }
+                        ManagerArguments::CloseAllSessions(slot_type) => {
+                            ManagerReturnValue::CloseAllSessions(
+                                real_manager.close_all_sessions(slot_type),
+                            )
+                        }
+                        ManagerArguments::StartSearch(session, attrs) => {
+                            ManagerReturnValue::StartSearch(
+                                real_manager.start_search(session, attrs),
+                            )
+                        }
+                        ManagerArguments::Search(session, max_objects) => {
+                            ManagerReturnValue::Search(real_manager.search(session, max_objects))
+                        }
+                        ManagerArguments::ClearSearch(session) => {
+                            ManagerReturnValue::ClearSearch(real_manager.clear_search(session))
+                        }
+                        ManagerArguments::GetAttributes(object_handle, attr_types) => {
+                            ManagerReturnValue::GetAttributes(
+                                real_manager.get_attributes(object_handle, attr_types),
+                            )
+                        }
+                        ManagerArguments::StartSign(session, key_handle, params) => {
+                            ManagerReturnValue::StartSign(
+                                real_manager.start_sign(session, key_handle, params),
+                            )
+                        }
+                        ManagerArguments::GetSignatureLength(session, data) => {
+                            ManagerReturnValue::GetSignatureLength(
+                                real_manager.get_signature_length(session, data),
+                            )
+                        }
+                        ManagerArguments::Sign(session, data) => {
+                            ManagerReturnValue::Sign(real_manager.sign(session, data))
+                        }
+                        ManagerArguments::Stop => ManagerReturnValue::Stop(Ok(())),
+                    };
+                    let stop_after_send = matches!(&results, &ManagerReturnValue::Stop(_));
+                    match manager_sender.send(results) {
+                        Ok(()) => {}
+                        Err(_) => {
+                            break;
+                        }
+                    }
+                    if stop_after_send {
+                        break;
+                    }
+                }
+            });
+        match thread_handle {
+            Ok(thread_handle) => Ok(ManagerProxy {
+                sender: proxy_sender,
+                receiver: proxy_receiver,
+                thread_handle: Some(thread_handle),
+            }),
+            Err(_) => Err(error_here!(ErrorType::LibraryFailure)),
+        }
+    }
+
+    fn proxy_call(&self, args: ManagerArguments) -> Result<ManagerReturnValue, Error> {
+        match self.sender.send(args) {
+            Ok(()) => {}
+            Err(_) => {
+                return Err(error_here!(ErrorType::LibraryFailure));
+            }
+        };
+        let result = match self.receiver.recv() {
+            Ok(result) => result,
+            Err(_) => {
+                return Err(error_here!(ErrorType::LibraryFailure));
+            }
+        };
+        Ok(result)
+    }
+
+    pub fn open_session(&mut self, slot_type: SlotType) -> Result<CK_SESSION_HANDLE, Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::OpenSession(slot_type),
+            ManagerReturnValue::OpenSession
+        )
+    }
+
+    pub fn close_session(&mut self, session: CK_SESSION_HANDLE) -> Result<(), Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::CloseSession(session),
+            ManagerReturnValue::CloseSession
+        )
+    }
+
+    pub fn close_all_sessions(&mut self, slot_type: SlotType) -> Result<(), Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::CloseAllSessions(slot_type),
+            ManagerReturnValue::CloseAllSessions
+        )
+    }
+
+    pub fn start_search(
+        &mut self,
+        session: CK_SESSION_HANDLE,
+        attrs: Vec<(CK_ATTRIBUTE_TYPE, Vec<u8>)>,
+    ) -> Result<(), Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::StartSearch(session, attrs),
+            ManagerReturnValue::StartSearch
+        )
+    }
+
+    pub fn search(
+        &mut self,
+        session: CK_SESSION_HANDLE,
+        max_objects: usize,
+    ) -> Result<Vec<CK_OBJECT_HANDLE>, Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::Search(session, max_objects),
+            ManagerReturnValue::Search
+        )
+    }
+
+    pub fn clear_search(&mut self, session: CK_SESSION_HANDLE) -> Result<(), Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::ClearSearch(session),
+            ManagerReturnValue::ClearSearch
+        )
+    }
+
+    pub fn get_attributes(
+        &self,
+        object_handle: CK_OBJECT_HANDLE,
+        attr_types: Vec<CK_ATTRIBUTE_TYPE>,
+    ) -> Result<Vec<Option<Vec<u8>>>, Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::GetAttributes(object_handle, attr_types,),
+            ManagerReturnValue::GetAttributes
+        )
+    }
+
+    pub fn start_sign(
+        &mut self,
+        session: CK_SESSION_HANDLE,
+        key_handle: CK_OBJECT_HANDLE,
+        params: Option<CK_RSA_PKCS_PSS_PARAMS>,
+    ) -> Result<(), Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::StartSign(session, key_handle, params),
+            ManagerReturnValue::StartSign
+        )
+    }
+
+    pub fn get_signature_length(
+        &self,
+        session: CK_SESSION_HANDLE,
+        data: Vec<u8>,
+    ) -> Result<usize, Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::GetSignatureLength(session, data),
+            ManagerReturnValue::GetSignatureLength
+        )
+    }
+
+    pub fn sign(&mut self, session: CK_SESSION_HANDLE, data: Vec<u8>) -> Result<Vec<u8>, Error> {
+        manager_proxy_fn_impl!(
+            self,
+            ManagerArguments::Sign(session, data),
+            ManagerReturnValue::Sign
+        )
+    }
+
+    pub fn stop(&mut self) -> Result<(), Error> {
+        manager_proxy_fn_impl!(self, ManagerArguments::Stop, ManagerReturnValue::Stop)?;
+        let thread_handle = match self.thread_handle.take() {
+            Some(thread_handle) => thread_handle,
+            None => return Err(error_here!(ErrorType::LibraryFailure)),
+        };
+        thread_handle
+            .join()
+            .map_err(|_| error_here!(ErrorType::LibraryFailure))
+    }
+}
+
+// Determines if the attributes of a given search correspond to NSS looking for all certificates or
+// private keys. Returns true if so, and false otherwise.
+// These searches are of the form:
+//   { { type: CKA_TOKEN, value: [1] },
+//     { type: CKA_CLASS, value: [CKO_CERTIFICATE or CKO_PRIVATE_KEY, as serialized bytes] } }
+// (although not necessarily in that order - see nssToken_TraverseCertificates and
+// nssToken_FindPrivateKeys)
+fn search_is_for_all_certificates_or_keys(
+    attrs: &[(CK_ATTRIBUTE_TYPE, Vec<u8>)],
+) -> Result<bool, Error> {
+    if attrs.len() != 2 {
+        return Ok(false);
+    }
+    let token_bytes = vec![1_u8];
+    let mut found_token = false;
+    let cko_certificate_bytes = serialize_uint(CKO_CERTIFICATE)?;
+    let cko_private_key_bytes = serialize_uint(CKO_PRIVATE_KEY)?;
+    let mut found_certificate_or_private_key = false;
+    for (attr_type, attr_value) in attrs.iter() {
+        if attr_type == &CKA_TOKEN && attr_value == &token_bytes {
+            found_token = true;
+        }
+        if attr_type == &CKA_CLASS
+            && (attr_value == &cko_certificate_bytes || attr_value == &cko_private_key_bytes)
+        {
+            found_certificate_or_private_key = true;
+        }
+    }
+    Ok(found_token && found_certificate_or_private_key)
+}
+
+const SUPPORTED_ATTRIBUTES: &[CK_ATTRIBUTE_TYPE] = &[
+    CKA_CLASS,
+    CKA_TOKEN,
+    CKA_LABEL,
+    CKA_ID,
+    CKA_VALUE,
+    CKA_ISSUER,
+    CKA_SERIAL_NUMBER,
+    CKA_SUBJECT,
+    CKA_PRIVATE,
+    CKA_KEY_TYPE,
+    CKA_MODULUS,
+    CKA_EC_PARAMS,
+];
+
+enum Object<B: ClientCertsBackend> {
+    Cert(B::Cert),
+    Key(B::Key),
+}
+
+impl<B: ClientCertsBackend> Object<B> {
+    fn matches(&self, slot_type: SlotType, attrs: &[(CK_ATTRIBUTE_TYPE, Vec<u8>)]) -> bool {
+        match self {
+            Object::Cert(cert) => cert.matches(slot_type, attrs),
+            Object::Key(key) => key.matches(slot_type, attrs),
+        }
+    }
+
+    fn get_attribute(&self, attribute: CK_ATTRIBUTE_TYPE) -> Option<&[u8]> {
+        match self {
+            Object::Cert(cert) => cert.get_attribute(attribute),
+            Object::Key(key) => key.get_attribute(attribute),
+        }
+    }
+
+    fn id(&self) -> Result<&[u8], Error> {
+        self.get_attribute(CKA_ID)
+            .ok_or_else(|| error_here!(ErrorType::LibraryFailure))
+    }
+
+    fn get_signature_length(
+        &mut self,
+        data: Vec<u8>,
+        params: &Option<CK_RSA_PKCS_PSS_PARAMS>,
+    ) -> Result<usize, Error> {
+        match self {
+            Object::Cert(_) => Err(error_here!(ErrorType::InvalidArgument)),
+            Object::Key(key) => key.get_signature_length(&data, params),
+        }
+    }
+
+    fn sign(
+        &mut self,
+        data: Vec<u8>,
+        params: &Option<CK_RSA_PKCS_PSS_PARAMS>,
+    ) -> Result<Vec<u8>, Error> {
+        match self {
+            Object::Cert(_) => Err(error_here!(ErrorType::InvalidArgument)),
+            Object::Key(key) => key.sign(&data, params),
+        }
+    }
+}
+
+/// The `Manager` keeps track of the state of this module with respect to the PKCS #11
+/// specification. This includes what sessions are open, which search and sign operations are
+/// ongoing, and what objects are known and by what handle.
+pub struct Manager<B: ClientCertsBackend> {
+    /// A map of session to session type (modern or legacy). Sessions can be created (opened) and
+    /// later closed.
+    sessions: BTreeMap<CK_SESSION_HANDLE, SlotType>,
+    /// A map of searches to PKCS #11 object handles that match those searches.
+    searches: BTreeMap<CK_SESSION_HANDLE, Vec<CK_OBJECT_HANDLE>>,
+    /// A map of sign operations to a pair of the object handle and optionally some params being
+    /// used by each one.
+    signs: BTreeMap<CK_SESSION_HANDLE, (CK_OBJECT_HANDLE, Option<CK_RSA_PKCS_PSS_PARAMS>)>,
+    /// A map of object handles to the underlying objects.
+    objects: BTreeMap<CK_OBJECT_HANDLE, Object<B>>,
+    /// A set of certificate identifiers (not the same as handles).
+    cert_ids: BTreeSet<Vec<u8>>,
+    /// A set of key identifiers (not the same as handles). For each id in this set, there should be
+    /// a corresponding identical id in the `cert_ids` set.
+    key_ids: BTreeSet<Vec<u8>>,
+    /// The next session handle to hand out.
+    next_session: CK_SESSION_HANDLE,
+    /// The next object handle to hand out.
+    next_handle: CK_OBJECT_HANDLE,
+    /// The last time the implementation looked for new objects in the backend.
+    /// The implementation does this search no more than once every 3 seconds.
+    last_scan_time: Option<Instant>,
+    backend: B,
+}
+
+impl<B: ClientCertsBackend> Manager<B> {
+    pub fn new(backend: B) -> Manager<B> {
+        Manager {
+            sessions: BTreeMap::new(),
+            searches: BTreeMap::new(),
+            signs: BTreeMap::new(),
+            objects: BTreeMap::new(),
+            cert_ids: BTreeSet::new(),
+            key_ids: BTreeSet::new(),
+            next_session: 1,
+            next_handle: 1,
+            last_scan_time: None,
+            backend,
+        }
+    }
+
+    /// When a new search session is opened (provided at least 3 seconds have elapsed since the
+    /// last session was opened), this searches for certificates and keys to expose. We
+    /// de-duplicate previously-found certificates and keys by keeping track of their IDs.
+    fn maybe_find_new_objects(&mut self) -> Result<(), Error> {
+        let now = Instant::now();
+        match self.last_scan_time {
+            Some(last_scan_time) => {
+                if now.duration_since(last_scan_time) < Duration::new(3, 0) {
+                    return Ok(());
+                }
+            }
+            None => {}
+        }
+        self.last_scan_time = Some(now);
+        let (certs, keys) = self.backend.find_objects()?;
+        for cert in certs {
+            let object = Object::Cert(cert);
+            if self.cert_ids.contains(object.id()?) {
+                continue;
+            }
+            self.cert_ids.insert(object.id()?.to_vec());
+            let handle = self.get_next_handle();
+            self.objects.insert(handle, object);
+        }
+        for key in keys {
+            let object = Object::Key(key);
+            if self.key_ids.contains(object.id()?) {
+                continue;
+            }
+            self.key_ids.insert(object.id()?.to_vec());
+            let handle = self.get_next_handle();
+            self.objects.insert(handle, object);
+        }
+        Ok(())
+    }
+
+    pub fn open_session(&mut self, slot_type: SlotType) -> Result<CK_SESSION_HANDLE, Error> {
+        let next_session = self.next_session;
+        self.next_session += 1;
+        self.sessions.insert(next_session, slot_type);
+        Ok(next_session)
+    }
+
+    pub fn close_session(&mut self, session: CK_SESSION_HANDLE) -> Result<(), Error> {
+        self.sessions
+            .remove(&session)
+            .ok_or_else(|| error_here!(ErrorType::InvalidInput))
+            .map(|_| ())
+    }
+
+    pub fn close_all_sessions(&mut self, slot_type: SlotType) -> Result<(), Error> {
+        let mut to_remove = Vec::new();
+        for (session, open_slot_type) in self.sessions.iter() {
+            if slot_type == *open_slot_type {
+                to_remove.push(*session);
+            }
+        }
+        for session in to_remove {
+            if self.sessions.remove(&session).is_none() {
+                return Err(error_here!(ErrorType::LibraryFailure));
+            }
+        }
+        Ok(())
+    }
+
+    fn get_next_handle(&mut self) -> CK_OBJECT_HANDLE {
+        let next_handle = self.next_handle;
+        self.next_handle += 1;
+        next_handle
+    }
+
+    /// PKCS #11 specifies that search operations happen in three phases: setup, get any matches
+    /// (this part may be repeated if the caller uses a small buffer), and end. This implementation
+    /// does all of the work up front and gathers all matching objects during setup and retains them
+    /// until they are retrieved and consumed via `search`.
+    pub fn start_search(
+        &mut self,
+        session: CK_SESSION_HANDLE,
+        attrs: Vec<(CK_ATTRIBUTE_TYPE, Vec<u8>)>,
+    ) -> Result<(), Error> {
+        let slot_type = match self.sessions.get(&session) {
+            Some(slot_type) => *slot_type,
+            None => return Err(error_here!(ErrorType::InvalidArgument)),
+        };
+        // If the search is for an attribute we don't support, no objects will match. This check
+        // saves us having to look through all of our objects.
+        for (attr, _) in &attrs {
+            if !SUPPORTED_ATTRIBUTES.contains(attr) {
+                self.searches.insert(session, Vec::new());
+                return Ok(());
+            }
+        }
+        // When NSS wants to find all certificates or all private keys, it will perform a search
+        // with a particular set of attributes. This implementation uses these searches as an
+        // indication for the backend to re-scan for new objects from tokens that may have been
+        // inserted or certificates that may have been imported into the OS. Since these searches
+        // are relatively rare, this minimizes the impact of doing these re-scans.
+        if search_is_for_all_certificates_or_keys(&attrs)? {
+            self.maybe_find_new_objects()?;
+        }
+        let mut handles = Vec::new();
+        for (handle, object) in &self.objects {
+            if object.matches(slot_type, &attrs) {
+                handles.push(*handle);
+            }
+        }
+        self.searches.insert(session, handles);
+        Ok(())
+    }
+
+    /// Given a session and a maximum number of object handles to return, attempts to retrieve up to
+    /// that many objects from the corresponding search. Updates the search so those objects are not
+    /// returned repeatedly. `max_objects` must be non-zero.
+    pub fn search(
+        &mut self,
+        session: CK_SESSION_HANDLE,
+        max_objects: usize,
+    ) -> Result<Vec<CK_OBJECT_HANDLE>, Error> {
+        if max_objects == 0 {
+            return Err(error_here!(ErrorType::InvalidArgument));
+        }
+        match self.searches.get_mut(&session) {
+            Some(search) => {
+                let split_at = if max_objects >= search.len() {
+                    0
+                } else {
+                    search.len() - max_objects
+                };
+                let to_return = search.split_off(split_at);
+                if to_return.len() > max_objects {
+                    return Err(error_here!(ErrorType::LibraryFailure));
+                }
+                Ok(to_return)
+            }
+            None => Err(error_here!(ErrorType::InvalidArgument)),
+        }
+    }
+
+    pub fn clear_search(&mut self, session: CK_SESSION_HANDLE) -> Result<(), Error> {
+        self.searches.remove(&session);
+        Ok(())
+    }
+
+    pub fn get_attributes(
+        &self,
+        object_handle: CK_OBJECT_HANDLE,
+        attr_types: Vec<CK_ATTRIBUTE_TYPE>,
+    ) -> Result<Vec<Option<Vec<u8>>>, Error> {
+        let object = match self.objects.get(&object_handle) {
+            Some(object) => object,
+            None => return Err(error_here!(ErrorType::InvalidArgument)),
+        };
+        let mut results = Vec::with_capacity(attr_types.len());
+        for attr_type in attr_types {
+            let result = object
+                .get_attribute(attr_type)
+                .map(|value| value.to_owned());
+            results.push(result);
+        }
+        Ok(results)
+    }
+
+    /// The way NSS uses PKCS #11 to sign data happens in two phases: setup and sign. This
+    /// implementation makes a note of which key is to be used (if it exists) during setup. When the
+    /// caller finishes with the sign operation, this implementation retrieves the key handle and
+    /// performs the signature.
+    pub fn start_sign(
+        &mut self,
+        session: CK_SESSION_HANDLE,
+        key_handle: CK_OBJECT_HANDLE,
+        params: Option<CK_RSA_PKCS_PSS_PARAMS>,
+    ) -> Result<(), Error> {
+        if self.signs.contains_key(&session) {
+            return Err(error_here!(ErrorType::InvalidArgument));
+        }
+        self.signs.insert(session, (key_handle, params));
+        Ok(())
+    }
+
+    pub fn get_signature_length(
+        &mut self,
+        session: CK_SESSION_HANDLE,
+        data: Vec<u8>,
+    ) -> Result<usize, Error> {
+        let (key_handle, params) = match self.signs.get(&session) {
+            Some((key_handle, params)) => (key_handle, params),
+            None => return Err(error_here!(ErrorType::InvalidArgument)),
+        };
+        let key = match self.objects.get_mut(key_handle) {
+            Some(key) => key,
+            None => return Err(error_here!(ErrorType::InvalidArgument)),
+        };
+        key.get_signature_length(data, params)
+    }
+
+    pub fn sign(&mut self, session: CK_SESSION_HANDLE, data: Vec<u8>) -> Result<Vec<u8>, Error> {
+        // Performing the signature (via C_Sign, which is the only way we support) finishes the sign
+        // operation, so it needs to be removed here.
+        let (key_handle, params) = match self.signs.remove(&session) {
+            Some((key_handle, params)) => (key_handle, params),
+            None => return Err(error_here!(ErrorType::InvalidArgument)),
+        };
+        let key = match self.objects.get_mut(&key_handle) {
+            Some(key) => key,
+            None => return Err(error_here!(ErrorType::InvalidArgument)),
+        };
+        key.sign(data, &params)
+    }
+}
diff --git a/security/manager/ssl/rsclientcerts/src/util.rs b/security/manager/ssl/rsclientcerts/src/util.rs
new file mode 100644
index 0000000000..d0011a0a2e
--- /dev/null
+++ b/security/manager/ssl/rsclientcerts/src/util.rs
@@ -0,0 +1,540 @@
+/* -*- Mode: rust; rust-indent-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use byteorder::{BigEndian, NativeEndian, ReadBytesExt, WriteBytesExt};
+use std::convert::TryInto;
+
+use crate::error::{Error, ErrorType};
+use crate::error_here;
+
+/// Accessing fields of packed structs is unsafe (it may be undefined behavior if the field isn't
+/// aligned). Since we're implementing a PKCS#11 module, we already have to trust the caller not to
+/// give us bad data, so normally we would deal with this by adding an unsafe block. If we do that,
+/// though, the compiler complains that the unsafe block is unnecessary. Thus, we use this macro to
+/// annotate the unsafe block to silence the compiler.
+#[macro_export]
+macro_rules! unsafe_packed_field_access {
+    ($e:expr) => {{
+        #[allow(unused_unsafe)]
+        let tmp = unsafe { $e };
+        tmp
+    }};
+}
+
+// The following ENCODED_OID_BYTES_* consist of the encoded bytes of an ASN.1
+// OBJECT IDENTIFIER specifying the indicated OID (in other words, the full
+// tag, length, and value).
+#[cfg(target_os = "macos")]
+pub const ENCODED_OID_BYTES_SECP256R1: &[u8] =
+    &[0x06, 0x08, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07];
+#[cfg(target_os = "macos")]
+pub const ENCODED_OID_BYTES_SECP384R1: &[u8] = &[0x06, 0x05, 0x2b, 0x81, 0x04, 0x00, 0x22];
+#[cfg(target_os = "macos")]
+pub const ENCODED_OID_BYTES_SECP521R1: &[u8] = &[0x06, 0x05, 0x2b, 0x81, 0x04, 0x00, 0x23];
+
+// The following OID_BYTES_* consist of the contents of the bytes of an ASN.1
+// OBJECT IDENTIFIER specifying the indicated OID (in other words, just the
+// value, and not the tag or length).
+#[cfg(target_os = "macos")]
+pub const OID_BYTES_SHA_256: &[u8] = &[0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01];
+#[cfg(target_os = "macos")]
+pub const OID_BYTES_SHA_384: &[u8] = &[0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02];
+#[cfg(target_os = "macos")]
+pub const OID_BYTES_SHA_512: &[u8] = &[0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03];
+#[cfg(target_os = "macos")]
+pub const OID_BYTES_SHA_1: &[u8] = &[0x2b, 0x0e, 0x03, 0x02, 0x1a];
+
+// This is a helper function to take a value and lay it out in memory how
+// PKCS#11 is expecting it.
+pub fn serialize_uint<T: TryInto<u64>>(value: T) -> Result<Vec<u8>, Error> {
+    let value_size = std::mem::size_of::<T>();
+    let mut value_buf = Vec::with_capacity(value_size);
+    let value_as_u64 = value
+        .try_into()
+        .map_err(|_| error_here!(ErrorType::ValueTooLarge))?;
+    value_buf
+        .write_uint::<NativeEndian>(value_as_u64, value_size)
+        .map_err(|_| error_here!(ErrorType::LibraryFailure))?;
+    Ok(value_buf)
+}
+
+/// Given a slice of DER bytes representing an RSA public key, extracts the bytes of the modulus
+/// as an unsigned integer. Also verifies that the public exponent is present (again as an
+/// unsigned integer). Finally verifies that reading these values consumes the entirety of the
+/// slice.
+/// RSAPublicKey ::= SEQUENCE {
+///     modulus           INTEGER,  -- n
+///     publicExponent    INTEGER   -- e
+/// }
+pub fn read_rsa_modulus(public_key: &[u8]) -> Result<Vec<u8>, Error> {
+    let mut sequence = Sequence::new(public_key)?;
+    let modulus_value = sequence.read_unsigned_integer()?;
+    let _exponent = sequence.read_unsigned_integer()?;
+    if !sequence.at_end() {
+        return Err(error_here!(ErrorType::ExtraInput));
+    }
+    Ok(modulus_value.to_vec())
+}
+
+/// Given a slice of DER bytes representing a DigestInfo, extracts the bytes of
+/// the OID of the hash algorithm and the digest.
+/// DigestInfo ::= SEQUENCE {
+///   digestAlgorithm DigestAlgorithmIdentifier,
+///   digest Digest }
+///
+/// DigestAlgorithmIdentifier ::= AlgorithmIdentifier
+///
+/// AlgorithmIdentifier  ::=  SEQUENCE  {
+///      algorithm               OBJECT IDENTIFIER,
+///      parameters              ANY DEFINED BY algorithm OPTIONAL  }
+///
+/// Digest ::= OCTET STRING
+pub fn read_digest_info(digest_info: &[u8]) -> Result<(&[u8], &[u8]), Error> {
+    let mut sequence = Sequence::new(digest_info)?;
+    let mut algorithm = sequence.read_sequence()?;
+    let oid = algorithm.read_oid()?;
+    algorithm.read_null()?;
+    if !algorithm.at_end() {
+        return Err(error_here!(ErrorType::ExtraInput));
+    }
+    let digest = sequence.read_octet_string()?;
+    if !sequence.at_end() {
+        return Err(error_here!(ErrorType::ExtraInput));
+    }
+    Ok((oid, digest))
+}
+
+/// Given a slice of DER bytes representing an ECDSA signature, extracts the bytes of `r` and `s`
+/// as unsigned integers. Also verifies that this consumes the entirety of the slice.
+///   Ecdsa-Sig-Value  ::=  SEQUENCE  {
+///        r     INTEGER,
+///        s     INTEGER  }
+#[cfg(target_os = "macos")]
+pub fn read_ec_sig_point(signature: &[u8]) -> Result<(&[u8], &[u8]), Error> {
+    let mut sequence = Sequence::new(signature)?;
+    let r = sequence.read_unsigned_integer()?;
+    let s = sequence.read_unsigned_integer()?;
+    if !sequence.at_end() {
+        return Err(error_here!(ErrorType::ExtraInput));
+    }
+    Ok((r, s))
+}
+
+/// Given a slice of DER bytes representing an X.509 certificate, extracts the encoded serial
+/// number, issuer, and subject. Does not verify that the remainder of the certificate is in any
+/// way well-formed.
+///   Certificate  ::=  SEQUENCE  {
+///           tbsCertificate       TBSCertificate,
+///           signatureAlgorithm   AlgorithmIdentifier,
+///           signatureValue       BIT STRING  }
+///
+///   TBSCertificate  ::=  SEQUENCE  {
+///           version         [0]  EXPLICIT Version DEFAULT v1,
+///           serialNumber         CertificateSerialNumber,
+///           signature            AlgorithmIdentifier,
+///           issuer               Name,
+///           validity             Validity,
+///           subject              Name,
+///           ...
+///
+///   CertificateSerialNumber  ::=  INTEGER
+///
+///   Name ::= CHOICE { -- only one possibility for now --
+///     rdnSequence  RDNSequence }
+///
+///   RDNSequence ::= SEQUENCE OF RelativeDistinguishedName
+///
+///   Validity ::= SEQUENCE {
+///        notBefore      Time,
+///        notAfter       Time  }
+#[allow(clippy::type_complexity)]
+pub fn read_encoded_certificate_identifiers(
+    certificate: &[u8],
+) -> Result<(Vec<u8>, Vec<u8>, Vec<u8>), Error> {
+    let mut certificate_sequence = Sequence::new(certificate)?;
+    let mut tbs_certificate_sequence = certificate_sequence.read_sequence()?;
+    let _version = tbs_certificate_sequence.read_tagged_value(0)?;
+    let serial_number = tbs_certificate_sequence.read_encoded_sequence_component(INTEGER)?;
+    let _signature = tbs_certificate_sequence.read_sequence()?;
+    let issuer =
+        tbs_certificate_sequence.read_encoded_sequence_component(SEQUENCE | CONSTRUCTED)?;
+    let _validity = tbs_certificate_sequence.read_sequence()?;
+    let subject =
+        tbs_certificate_sequence.read_encoded_sequence_component(SEQUENCE | CONSTRUCTED)?;
+    Ok((serial_number, issuer, subject))
+}
+
+/// Helper macro for reading some bytes from a slice while checking the slice is long enough.
+/// Returns a pair consisting of a slice of the bytes read and a slice of the rest of the bytes
+/// from the original slice.
+macro_rules! try_read_bytes {
+    ($data:ident, $len:expr) => {{
+        if $data.len() < $len {
+            return Err(error_here!(ErrorType::TruncatedInput));
+        }
+        $data.split_at($len)
+    }};
+}
+
+/// ASN.1 tag identifying an integer.
+const INTEGER: u8 = 0x02;
+/// ASN.1 tag identifying an octet string.
+const OCTET_STRING: u8 = 0x04;
+/// ASN.1 tag identifying a null value.
+const NULL: u8 = 0x05;
+/// ASN.1 tag identifying an object identifier (OID).
+const OBJECT_IDENTIFIER: u8 = 0x06;
+/// ASN.1 tag identifying a sequence.
+const SEQUENCE: u8 = 0x10;
+/// ASN.1 tag modifier identifying an item as constructed.
+const CONSTRUCTED: u8 = 0x20;
+/// ASN.1 tag modifier identifying an item as context-specific.
+const CONTEXT_SPECIFIC: u8 = 0x80;
+
+/// A helper struct for reading items from a DER SEQUENCE (in this case, all sequences are
+/// assumed to be CONSTRUCTED).
+struct Sequence<'a> {
+    /// The contents of the SEQUENCE.
+    contents: Der<'a>,
+}
+
+impl<'a> Sequence<'a> {
+    fn new(input: &'a [u8]) -> Result<Sequence<'a>, Error> {
+        let mut der = Der::new(input);
+        let (_, _, sequence_bytes) = der.read_tlv(SEQUENCE | CONSTRUCTED)?;
+        // We're assuming we want to consume the entire input for now.
+        if !der.at_end() {
+            return Err(error_here!(ErrorType::ExtraInput));
+        }
+        Ok(Sequence {
+            contents: Der::new(sequence_bytes),
+        })
+    }
+
+    // TODO: we're not exhaustively validating this integer
+    fn read_unsigned_integer(&mut self) -> Result<&'a [u8], Error> {
+        let (_, _, bytes) = self.contents.read_tlv(INTEGER)?;
+        if bytes.is_empty() {
+            return Err(error_here!(ErrorType::InvalidInput));
+        }
+        // There may be a leading zero (we should also check that the first bit
+        // of the rest of the integer is set).
+        if bytes[0] == 0 && bytes.len() > 1 {
+            let (_, integer) = bytes.split_at(1);
+            Ok(integer)
+        } else {
+            Ok(bytes)
+        }
+    }
+
+    fn read_octet_string(&mut self) -> Result<&'a [u8], Error> {
+        let (_, _, bytes) = self.contents.read_tlv(OCTET_STRING)?;
+        Ok(bytes)
+    }
+
+    fn read_oid(&mut self) -> Result<&'a [u8], Error> {
+        let (_, _, bytes) = self.contents.read_tlv(OBJECT_IDENTIFIER)?;
+        Ok(bytes)
+    }
+
+    fn read_null(&mut self) -> Result<(), Error> {
+        let (_, _, bytes) = self.contents.read_tlv(NULL)?;
+        if bytes.is_empty() {
+            Ok(())
+        } else {
+            Err(error_here!(ErrorType::InvalidInput))
+        }
+    }
+
+    fn read_sequence(&mut self) -> Result<Sequence<'a>, Error> {
+        let (_, _, sequence_bytes) = self.contents.read_tlv(SEQUENCE | CONSTRUCTED)?;
+        Ok(Sequence {
+            contents: Der::new(sequence_bytes),
+        })
+    }
+
+    fn read_tagged_value(&mut self, tag: u8) -> Result<&'a [u8], Error> {
+        let (_, _, tagged_value_bytes) = self
+            .contents
+            .read_tlv(CONTEXT_SPECIFIC | CONSTRUCTED | tag)?;
+        Ok(tagged_value_bytes)
+    }
+
+    fn read_encoded_sequence_component(&mut self, tag: u8) -> Result<Vec<u8>, Error> {
+        let (tag, length, value) = self.contents.read_tlv(tag)?;
+        let mut encoded_component_bytes = length;
+        encoded_component_bytes.insert(0, tag);
+        encoded_component_bytes.extend_from_slice(value);
+        Ok(encoded_component_bytes)
+    }
+
+    fn at_end(&self) -> bool {
+        self.contents.at_end()
+    }
+}
+
+/// A helper struct for reading DER data. The contents are treated like a cursor, so its position
+/// is updated as data is read.
+struct Der<'a> {
+    contents: &'a [u8],
+}
+
+impl<'a> Der<'a> {
+    fn new(contents: &'a [u8]) -> Der<'a> {
+        Der { contents }
+    }
+
+    // In theory, a caller could encounter an error and try another operation, in which case we may
+    // be in an inconsistent state. As long as this implementation isn't exposed to code that would
+    // use it incorrectly (i.e. it stays in this module and we only expose a stateless API), it
+    // should be safe.
+    /// Given an expected tag, reads the next (tag, lengh, value) from the contents. Most
+    /// consumers will only be interested in the value, but some may want the entire encoded
+    /// contents, in which case the returned tuple can be concatenated.
+    fn read_tlv(&mut self, tag: u8) -> Result<(u8, Vec<u8>, &'a [u8]), Error> {
+        let contents = self.contents;
+        let (tag_read, rest) = try_read_bytes!(contents, 1);
+        if tag_read[0] != tag {
+            return Err(error_here!(ErrorType::InvalidInput));
+        }
+        let mut accumulated_length_bytes = Vec::with_capacity(4);
+        let (length1, rest) = try_read_bytes!(rest, 1);
+        accumulated_length_bytes.extend_from_slice(length1);
+        let (length, to_read_from) = if length1[0] < 0x80 {
+            (length1[0] as usize, rest)
+        } else if length1[0] == 0x81 {
+            let (length, rest) = try_read_bytes!(rest, 1);
+            accumulated_length_bytes.extend_from_slice(length);
+            if length[0] < 0x80 {
+                return Err(error_here!(ErrorType::InvalidInput));
+            }
+            (length[0] as usize, rest)
+        } else if length1[0] == 0x82 {
+            let (mut lengths, rest) = try_read_bytes!(rest, 2);
+            accumulated_length_bytes.extend_from_slice(lengths);
+            let length = lengths
+                .read_u16::<BigEndian>()
+                .map_err(|_| error_here!(ErrorType::LibraryFailure))?;
+            if length < 256 {
+                return Err(error_here!(ErrorType::InvalidInput));
+            }
+            (length as usize, rest)
+        } else {
+            return Err(error_here!(ErrorType::UnsupportedInput));
+        };
+        let (contents, rest) = try_read_bytes!(to_read_from, length);
+        self.contents = rest;
+        Ok((tag, accumulated_length_bytes, contents))
+    }
+
+    fn at_end(&self) -> bool {
+        self.contents.is_empty()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn der_test_empty_input() {
+        let input = Vec::new();
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(INTEGER).is_err());
+    }
+
+    #[test]
+    fn der_test_no_length() {
+        let input = vec![INTEGER];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(INTEGER).is_err());
+    }
+
+    #[test]
+    fn der_test_empty_sequence() {
+        let input = vec![SEQUENCE, 0];
+        let mut der = Der::new(&input);
+        let read_result = der.read_tlv(SEQUENCE);
+        assert!(read_result.is_ok());
+        let (tag, length, sequence_bytes) = read_result.unwrap();
+        assert_eq!(tag, SEQUENCE);
+        assert_eq!(length, vec![0]);
+        assert_eq!(sequence_bytes.len(), 0);
+        assert!(der.at_end());
+    }
+
+    #[test]
+    fn der_test_not_at_end() {
+        let input = vec![SEQUENCE, 0, 1];
+        let mut der = Der::new(&input);
+        let read_result = der.read_tlv(SEQUENCE);
+        assert!(read_result.is_ok());
+        let (tag, length, sequence_bytes) = read_result.unwrap();
+        assert_eq!(tag, SEQUENCE);
+        assert_eq!(length, vec![0]);
+        assert_eq!(sequence_bytes.len(), 0);
+        assert!(!der.at_end());
+    }
+
+    #[test]
+    fn der_test_wrong_tag() {
+        let input = vec![SEQUENCE, 0];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(INTEGER).is_err());
+    }
+
+    #[test]
+    fn der_test_truncated_two_byte_length() {
+        let input = vec![SEQUENCE, 0x81];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(SEQUENCE).is_err());
+    }
+
+    #[test]
+    fn der_test_truncated_three_byte_length() {
+        let input = vec![SEQUENCE, 0x82, 1];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(SEQUENCE).is_err());
+    }
+
+    #[test]
+    fn der_test_truncated_data() {
+        let input = vec![SEQUENCE, 20, 1];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(SEQUENCE).is_err());
+    }
+
+    #[test]
+    fn der_test_sequence() {
+        let input = vec![
+            SEQUENCE, 20, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 0, 0,
+        ];
+        let mut der = Der::new(&input);
+        let result = der.read_tlv(SEQUENCE);
+        assert!(result.is_ok());
+        let (tag, length, value) = result.unwrap();
+        assert_eq!(tag, SEQUENCE);
+        assert_eq!(length, vec![20]);
+        assert_eq!(
+            value,
+            [1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 0, 0]
+        );
+        assert!(der.at_end());
+    }
+
+    #[test]
+    fn der_test_not_shortest_two_byte_length_encoding() {
+        let input = vec![SEQUENCE, 0x81, 1, 1];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(SEQUENCE).is_err());
+    }
+
+    #[test]
+    fn der_test_not_shortest_three_byte_length_encoding() {
+        let input = vec![SEQUENCE, 0x82, 0, 1, 1];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(SEQUENCE).is_err());
+    }
+
+    #[test]
+    fn der_test_indefinite_length_unsupported() {
+        let input = vec![SEQUENCE, 0x80, 1, 2, 3, 0x00, 0x00];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(SEQUENCE).is_err());
+    }
+
+    #[test]
+    fn der_test_input_too_long() {
+        // This isn't valid DER (the contents of the SEQUENCE are truncated), but it demonstrates
+        // that we don't try to read too much if we're given a long length (and also that we don't
+        // support lengths 2^16 and up).
+        let input = vec![SEQUENCE, 0x83, 0x01, 0x00, 0x01, 1, 1, 1, 1];
+        let mut der = Der::new(&input);
+        assert!(der.read_tlv(SEQUENCE).is_err());
+    }
+
+    #[test]
+    fn empty_input_fails() {
+        let empty = Vec::new();
+        assert!(read_rsa_modulus(&empty).is_err());
+        #[cfg(target_os = "macos")]
+        assert!(read_ec_sig_point(&empty).is_err());
+        assert!(read_encoded_certificate_identifiers(&empty).is_err());
+    }
+
+    #[test]
+    fn empty_sequence_fails() {
+        let empty = vec![SEQUENCE | CONSTRUCTED];
+        assert!(read_rsa_modulus(&empty).is_err());
+        #[cfg(target_os = "macos")]
+        assert!(read_ec_sig_point(&empty).is_err());
+        assert!(read_encoded_certificate_identifiers(&empty).is_err());
+    }
+
+    #[test]
+    fn test_read_rsa_modulus() {
+        let rsa_key = include_bytes!("../test/rsa.bin");
+        let result = read_rsa_modulus(rsa_key);
+        assert!(result.is_ok());
+        let modulus = result.unwrap();
+        assert_eq!(modulus, include_bytes!("../test/modulus.bin").to_vec());
+    }
+
+    #[test]
+    fn test_read_certificate_identifiers() {
+        let certificate = include_bytes!("../test/certificate.bin");
+        let result = read_encoded_certificate_identifiers(certificate);
+        assert!(result.is_ok());
+        let (serial_number, issuer, subject) = result.unwrap();
+        assert_eq!(
+            serial_number,
+            &[
+                0x02, 0x14, 0x3f, 0xed, 0x7b, 0x43, 0x47, 0x8a, 0x53, 0x42, 0x5b, 0x0d, 0x50, 0xe1,
+                0x37, 0x88, 0x2a, 0x20, 0x3f, 0x31, 0x17, 0x20
+            ]
+        );
+        assert_eq!(
+            issuer,
+            &[
+                0x30, 0x12, 0x31, 0x10, 0x30, 0x0e, 0x06, 0x03, 0x55, 0x04, 0x03, 0x0c, 0x07, 0x54,
+                0x65, 0x73, 0x74, 0x20, 0x43, 0x41
+            ]
+        );
+        assert_eq!(
+            subject,
+            &[
+                0x30, 0x1a, 0x31, 0x18, 0x30, 0x16, 0x06, 0x03, 0x55, 0x04, 0x03, 0x0c, 0x0f, 0x54,
+                0x65, 0x73, 0x74, 0x20, 0x45, 0x6e, 0x64, 0x2d, 0x65, 0x6e, 0x74, 0x69, 0x74, 0x79
+            ]
+        );
+    }
+
+    #[test]
+    #[cfg(target_os = "windows")]
+    fn test_read_digest() {
+        // SEQUENCE
+        //   SEQUENCE
+        //     OBJECT IDENTIFIER 2.16.840.1.101.3.4.2.1 sha-256
+        //       NULL
+        //   OCTET STRING 1A7FCDB9A5F649F954885CFE145F3E93F0D1FA72BE980CC6EC82C70E1407C7D2
+        let digest_info = [
+            0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x1, 0x65, 0x03, 0x04, 0x02,
+            0x01, 0x05, 0x00, 0x04, 0x20, 0x1a, 0x7f, 0xcd, 0xb9, 0xa5, 0xf6, 0x49, 0xf9, 0x54,
+            0x88, 0x5c, 0xfe, 0x14, 0x5f, 0x3e, 0x93, 0xf0, 0xd1, 0xfa, 0x72, 0xbe, 0x98, 0x0c,
+            0xc6, 0xec, 0x82, 0xc7, 0x0e, 0x14, 0x07, 0xc7, 0xd2,
+        ];
+        let result = read_digest(&digest_info);
+        assert!(result.is_ok());
+        let digest = result.unwrap();
+        assert_eq!(
+            digest,
+            &[
+                0x1a, 0x7f, 0xcd, 0xb9, 0xa5, 0xf6, 0x49, 0xf9, 0x54, 0x88, 0x5c, 0xfe, 0x14, 0x5f,
+                0x3e, 0x93, 0xf0, 0xd1, 0xfa, 0x72, 0xbe, 0x98, 0x0c, 0xc6, 0xec, 0x82, 0xc7, 0x0e,
+                0x14, 0x07, 0xc7, 0xd2
+            ]
+        );
+    }
+}