[webcrypto] Make operations run on a background thread so they don't block the blink thread.

content/child/webcrypto/webcrypto_impl.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/child/webcrypto/webcrypto_impl.h"
 
+#include "base/bind.h"
+#include "base/lazy_instance.h"
+#include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task_runner.h"
+#include "base/thread_task_runner_handle.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "base/threading/worker_pool.h"
 #include "content/child/webcrypto/crypto_data.h"
 #include "content/child/webcrypto/shared_crypto.h"
 #include "content/child/webcrypto/status.h"
 #include "content/child/webcrypto/webcrypto_util.h"
+#include "content/child/worker_thread_task_runner.h"
 #include "third_party/WebKit/public/platform/WebCryptoKeyAlgorithm.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 
 namespace content {
 
 using webcrypto::Status;
 
 namespace {
 
+// ---------------------
+// Threading
+// ---------------------
+//
+// WebCrypto operations can be slow. For instance generating an RSA key can
+// take hundreds of milliseconds to several seconds.
+//
+// Moreover the underlying crypto libraries are not threadsafe when operating
+// on the same key.
+//
+// The strategy used here is to run a sequenced worker pool for all WebCrypto
+// operations. This pool (of 1 threads) is also used by requests started from
+// Blink Web Workers.
+//
+// A few notes to keep in mind:
+//
+// * PostTaskAndReply() cannot be used for two reasons:
+//
+//   (1) Blink web worker threads do not have an associated message loop so
+//       construction of the reply callback will crash.
+//
+//   (2) PostTaskAndReply() handles failure posting the reply by leaking the
+//       callback, rather than destroying it. In the case of Web Workers this
+//       condition is reachable via normal execution, since Web Workers can
+//       be stopped before the WebCrypto operation has finished. A policy of
+//       leaking would therefore be problematic.
+//
+// * blink::WebArrayBuffer is NOT threadsafe, and should therefore be allocated
+//   on the target Blink thread.
+//
+//   TODO(eroman): Is there any way around this? Copying the result between
+//                 threads is silly.
+//
+// * WebCryptoAlgorithm and WebCryptoKey are threadsafe (however the key's
+//   handle(), which wraps an NSS/OpenSSL type, may not be and should only be
+//   used from the webcrypto thread).
+//
+// * blink::WebCryptoResult is not threadsafe and should only be operated on
+//   the target Blink thread. HOWEVER, it is safe to delete it from any thread.
+//   This can happen if by the time the operation has completed in the crypto
+//   worker pool, the Blink worker thread that initiated the request is gone.
+//   Posting back to the origin thread will fail, and the WebCryptoResult will
+//   be deleted while running in the crypto worker pool.
+class CryptoThreadPool {
+ public:
+  CryptoThreadPool()
+      : worker_pool_(new base::SequencedWorkerPool(1, "WebCrypto")),
+        task_runner_(worker_pool_->GetSequencedTaskRunnerWithShutdownBehavior(
+            worker_pool_->GetSequenceToken(),
+            base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN)) {}
+
+  static bool PostTask(const tracked_objects::Location& from_here,
+                       const base::Closure& task);
+
+ private:
+  scoped_refptr<base::SequencedWorkerPool> worker_pool_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+};
+
+base::LazyInstance<CryptoThreadPool>::Leaky crypto_thread_pool =
+    LAZY_INSTANCE_INITIALIZER;
+
+bool CryptoThreadPool::PostTask(const tracked_objects::Location& from_here,
+                                const base::Closure& task) {
+  return crypto_thread_pool.Get().task_runner_->PostTask(from_here, task);
+}
+
+void CompleteWithThreadPoolError(blink::WebCryptoResult* result) {
+  result->completeWithError(blink::WebCryptoErrorTypeOperation,
+                            "Failed posting to crypto worker pool");
+}
+
 void CompleteWithError(const Status& status, blink::WebCryptoResult* result) {
   DCHECK(status.IsError());
 
   result->completeWithError(status.error_type(),
                             blink::WebString::fromUTF8(status.error_details()));
 }
 
+void CompleteWithBufferOrError(const Status& status,
+                               const std::vector<uint8>& buffer,
+                               blink::WebCryptoResult* result) {
+  if (status.IsError()) {
+    CompleteWithError(status, result);
+  } else {
+    if (buffer.size() > UINT_MAX) {
+      // WebArrayBuffers have a smaller range than std::vector<>, so
+      // theoretically this could overflow.
+      CompleteWithError(Status::ErrorUnexpected(), result);
+    } else {
+      result->completeWithBuffer(webcrypto::Uint8VectorStart(buffer),
+                                 buffer.size());
+    }
+  }
+}
+
+void CompleteWithKeyOrError(const Status& status,
+                            const blink::WebCryptoKey& key,
+                            blink::WebCryptoResult* result) {
+  if (status.IsError()) {
+    CompleteWithError(status, result);
+  } else {
+    result->completeWithKey(key);
+  }
+}
+
 bool IsAlgorithmAsymmetric(const blink::WebCryptoAlgorithm& algorithm) {
   // TODO(padolph): include all other asymmetric algorithms once they are
   // defined, e.g. EC and DH.
   return (algorithm.id() == blink::WebCryptoAlgorithmIdRsaEsPkcs1v1_5 ||
           algorithm.id() == blink::WebCryptoAlgorithmIdRsaSsaPkcs1v1_5 ||
           algorithm.id() == blink::WebCryptoAlgorithmIdRsaOaep);
 }
 
+// Gets a task runner for the current thread. The current thread is either:
+//
+//   * The main Blink thread
+//   * A Blink web worker thread
+//
+// A different mechanism is needed for posting to these threads. The main
+// thread has an associated message loop and can simply use
+// base::ThreadTaskRunnerHandle. Whereas the web worker threads are managed by
+// Blink and need to be indirected through WorkerThreadTaskRunner.
+scoped_refptr<base::TaskRunner> GetCurrentBlinkThread() {
+  if (base::ThreadTaskRunnerHandle::IsSet())
+    return base::ThreadTaskRunnerHandle::Get();
+  return WorkerThreadTaskRunner::current();
+}
+
+// --------------------------------------------------------------------
+// State
+// --------------------------------------------------------------------
+//
+// Explicit state classes are used rather than base::Bind(). This is done
+// both for clarity, but also to avoid extraneous allocations for things
+// like passing buffers and result objects between threads.
+//
+// BaseState is the base class common to all of the async operations, and
+// keeps track of the thread to complete on, the error state, and the
+// callback into Blink.
+//
+// Ownership of the State object is passed between the crypto thread and the
+// Blink thread. Under normal completion it is destroyed on the Blink thread.
+// However it may also be destroyed on the crypto thread if the Blink thread
+// has vanished (which can happen for Blink web worker threads).
+
+struct BaseState {
+  explicit BaseState(const blink::WebCryptoResult& result)
+      : origin_thread(GetCurrentBlinkThread()), result(result) {}
+
+  scoped_refptr<base::TaskRunner> origin_thread;
+
+  webcrypto::Status status;
+  blink::WebCryptoResult result;
+
+ protected:
+  // Since there is no virtual destructor, must not delete directly as a
+  // BaseState.
+  ~BaseState() {}
+};
+
+struct EncryptState : public BaseState {
+  EncryptState(const blink::WebCryptoAlgorithm& algorithm,
+               const blink::WebCryptoKey& key,
+               const unsigned char* data,
+               unsigned int data_size,
+               const blink::WebCryptoResult& result)
+      : BaseState(result),
+        algorithm(algorithm),
+        key(key),
+        data(data, data + data_size) {}
+
+  const blink::WebCryptoAlgorithm algorithm;
+  const blink::WebCryptoKey key;
+  const std::vector<uint8> data;
+
+  std::vector<uint8> buffer;
+};
+
+typedef EncryptState DecryptState;
+typedef EncryptState DigestState;
+
+struct GenerateKeyState : public BaseState {
+  GenerateKeyState(const blink::WebCryptoAlgorithm& algorithm,
+                   bool extractable,
+                   blink::WebCryptoKeyUsageMask usage_mask,
+                   const blink::WebCryptoResult& result)
+      : BaseState(result),
+        algorithm(algorithm),
+        extractable(extractable),
+        usage_mask(usage_mask),
+        public_key(blink::WebCryptoKey::createNull()),
+        private_key(blink::WebCryptoKey::createNull()),
+        is_asymmetric(false) {}
+
+  const blink::WebCryptoAlgorithm algorithm;
+  const bool extractable;
+  const blink::WebCryptoKeyUsageMask usage_mask;
+
+  // If |is_asymmetric| is false, then |public_key| is understood to mean the
+  // symmetric key, and |private_key| is unused.
+  blink::WebCryptoKey public_key;
+  blink::WebCryptoKey private_key;
+  bool is_asymmetric;
+};
+
+struct ImportKeyState : public BaseState {
+  ImportKeyState(blink::WebCryptoKeyFormat format,
+                 const unsigned char* key_data,
+                 unsigned int key_data_size,
+                 const blink::WebCryptoAlgorithm& algorithm,
+                 bool extractable,
+                 blink::WebCryptoKeyUsageMask usage_mask,
+                 const blink::WebCryptoResult& result)
+      : BaseState(result),
+        format(format),
+        key_data(key_data, key_data + key_data_size),
+        algorithm(algorithm),
+        extractable(extractable),
+        usage_mask(usage_mask),
+        key(blink::WebCryptoKey::createNull()) {}
+
+  const blink::WebCryptoKeyFormat format;
+  const std::vector<uint8> key_data;
+  const blink::WebCryptoAlgorithm algorithm;
+  const bool extractable;
+  const blink::WebCryptoKeyUsageMask usage_mask;
+
+  blink::WebCryptoKey key;
+};
+
+struct ExportKeyState : public BaseState {
+  ExportKeyState(blink::WebCryptoKeyFormat format,
+                 const blink::WebCryptoKey& key,
+                 const blink::WebCryptoResult& result)
+      : BaseState(result), format(format), key(key) {}
+
+  const blink::WebCryptoKeyFormat format;
+  const blink::WebCryptoKey key;
+
+  std::vector<uint8> buffer;
+};
+
+typedef EncryptState SignState;
+
+struct VerifySignatureState : public BaseState {
+  VerifySignatureState(const blink::WebCryptoAlgorithm& algorithm,
+                       const blink::WebCryptoKey& key,
+                       const unsigned char* signature,
+                       unsigned int signature_size,
+                       const unsigned char* data,
+                       unsigned int data_size,
+                       const blink::WebCryptoResult& result)
+      : BaseState(result),
+        algorithm(algorithm),
+        key(key),
+        signature(signature, signature + signature_size),
+        data(data, data + data_size),
+        verify_result(false) {}
+
+  const blink::WebCryptoAlgorithm algorithm;
+  const blink::WebCryptoKey key;
+  const std::vector<uint8> signature;
+  const std::vector<uint8> data;
+
+  bool verify_result;
+};
+
+struct WrapKeyState : public BaseState {
+  WrapKeyState(blink::WebCryptoKeyFormat format,
+               const blink::WebCryptoKey& key,
+               const blink::WebCryptoKey& wrapping_key,
+               const blink::WebCryptoAlgorithm& wrap_algorithm,
+               const blink::WebCryptoResult& result)
+      : BaseState(result),
+        format(format),
+        key(key),
+        wrapping_key(wrapping_key),
+        wrap_algorithm(wrap_algorithm) {}
+
+  const blink::WebCryptoKeyFormat format;
+  const blink::WebCryptoKey key;
+  const blink::WebCryptoKey wrapping_key;
+  const blink::WebCryptoAlgorithm wrap_algorithm;
+
+  std::vector<uint8> buffer;
+};
+
+struct UnwrapKeyState : public BaseState {
+  UnwrapKeyState(blink::WebCryptoKeyFormat format,
+                 const unsigned char* wrapped_key,
+                 unsigned wrapped_key_size,
+                 const blink::WebCryptoKey& wrapping_key,
+                 const blink::WebCryptoAlgorithm& unwrap_algorithm,
+                 const blink::WebCryptoAlgorithm& unwrapped_key_algorithm,
+                 bool extractable,
+                 blink::WebCryptoKeyUsageMask usages,
+                 const blink::WebCryptoResult& result)
+      : BaseState(result),
+        format(format),
+        wrapped_key(wrapped_key, wrapped_key + wrapped_key_size),
+        wrapping_key(wrapping_key),
+        unwrap_algorithm(unwrap_algorithm),
+        unwrapped_key_algorithm(unwrapped_key_algorithm),
+        extractable(extractable),
+        usages(usages),
+        unwrapped_key(blink::WebCryptoKey::createNull()) {}
+
+  const blink::WebCryptoKeyFormat format;
+  const std::vector<uint8> wrapped_key;
+  const blink::WebCryptoKey wrapping_key;
+  const blink::WebCryptoAlgorithm unwrap_algorithm;
+  const blink::WebCryptoAlgorithm unwrapped_key_algorithm;
+  const bool extractable;
+  const blink::WebCryptoKeyUsageMask usages;
+
+  blink::WebCryptoKey unwrapped_key;
+};
+
+// --------------------------------------------------------------------
+// Wrapper functions
+// --------------------------------------------------------------------
+//
+// * The methods named Do*() run on the crypto thread.
+// * The methods named Do*Reply() run on the target Blink thread
+
+void DoEncryptReply(scoped_ptr<EncryptState> state) {
+  CompleteWithBufferOrError(state->status, state->buffer, &state->result);
+}
+
+void DoEncrypt(scoped_ptr<EncryptState> passed_state) {
+  EncryptState* state = passed_state.get();
+  state->status = webcrypto::Encrypt(state->algorithm,
+                                     state->key,
+                                     webcrypto::CryptoData(state->data),
+                                     &state->buffer);
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoEncryptReply, Passed(&passed_state)));
+}
+
+void DoDecryptReply(scoped_ptr<DecryptState> state) {
+  CompleteWithBufferOrError(state->status, state->buffer, &state->result);
+}
+
+void DoDecrypt(scoped_ptr<DecryptState> passed_state) {
+  DecryptState* state = passed_state.get();
+  state->status = webcrypto::Decrypt(state->algorithm,
+                                     state->key,
+                                     webcrypto::CryptoData(state->data),
+                                     &state->buffer);
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoDecryptReply, Passed(&passed_state)));
+}
+
+void DoDigestReply(scoped_ptr<DigestState> state) {
+  CompleteWithBufferOrError(state->status, state->buffer, &state->result);
+}
+
+void DoDigest(scoped_ptr<DigestState> passed_state) {
+  DigestState* state = passed_state.get();
+  state->status = webcrypto::Digest(
+      state->algorithm, webcrypto::CryptoData(state->data), &state->buffer);
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoDigestReply, Passed(&passed_state)));
+}
+
+void DoGenerateKeyReply(scoped_ptr<GenerateKeyState> state) {
+  if (state->status.IsError()) {
+    CompleteWithError(state->status, &state->result);
+  } else {
+    if (state->is_asymmetric)
+      state->result.completeWithKeyPair(state->public_key, state->private_key);
+    else
+      state->result.completeWithKey(state->public_key);
+  }
+}
+
+void DoGenerateKey(scoped_ptr<GenerateKeyState> passed_state) {
+  GenerateKeyState* state = passed_state.get();
+  state->is_asymmetric = IsAlgorithmAsymmetric(state->algorithm);
+  if (state->is_asymmetric) {
+    state->status = webcrypto::GenerateKeyPair(state->algorithm,
+                                               state->extractable,
+                                               state->usage_mask,
+                                               &state->public_key,
+                                               &state->private_key);
+
+    if (state->status.IsSuccess()) {
+      DCHECK(state->public_key.handle());
+      DCHECK(state->private_key.handle());
+      DCHECK_EQ(state->algorithm.id(), state->public_key.algorithm().id());
+      DCHECK_EQ(state->algorithm.id(), state->private_key.algorithm().id());
+      DCHECK_EQ(true, state->public_key.extractable());
+      DCHECK_EQ(state->extractable, state->private_key.extractable());
+      DCHECK_EQ(state->usage_mask, state->public_key.usages());
+      DCHECK_EQ(state->usage_mask, state->private_key.usages());
+    }
+  } else {
+    blink::WebCryptoKey* key = &state->public_key;
+
+    state->status = webcrypto::GenerateSecretKey(
+        state->algorithm, state->extractable, state->usage_mask, key);
+
+    if (state->status.IsSuccess()) {
+      DCHECK(key->handle());
+      DCHECK_EQ(state->algorithm.id(), key->algorithm().id());
+      DCHECK_EQ(state->extractable, key->extractable());
+      DCHECK_EQ(state->usage_mask, key->usages());
+    }
+  }
+
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoGenerateKeyReply, Passed(&passed_state)));
+}
+
+void DoImportKeyReply(scoped_ptr<ImportKeyState> state) {
+  CompleteWithKeyOrError(state->status, state->key, &state->result);
+}
+
+void DoImportKey(scoped_ptr<ImportKeyState> passed_state) {
+  ImportKeyState* state = passed_state.get();
+  state->status = webcrypto::ImportKey(state->format,
+                                       webcrypto::CryptoData(state->key_data),
+                                       state->algorithm,
+                                       state->extractable,
+                                       state->usage_mask,
+                                       &state->key);
+  if (state->status.IsSuccess()) {
+    DCHECK(state->key.handle());
+    DCHECK(!state->key.algorithm().isNull());
+    DCHECK_EQ(state->extractable, state->key.extractable());
+  }
+
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoImportKeyReply, Passed(&passed_state)));
+}
+
+void DoExportKeyReply(scoped_ptr<ExportKeyState> state) {
+  CompleteWithBufferOrError(state->status, state->buffer, &state->result);
+}
+
+void DoExportKey(scoped_ptr<ExportKeyState> passed_state) {
+  ExportKeyState* state = passed_state.get();
+  state->status =
+      webcrypto::ExportKey(state->format, state->key, &state->buffer);
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoExportKeyReply, Passed(&passed_state)));
+}
+
+void DoSignReply(scoped_ptr<SignState> state) {
+  CompleteWithBufferOrError(state->status, state->buffer, &state->result);
+}
+
+void DoSign(scoped_ptr<SignState> passed_state) {
+  SignState* state = passed_state.get();
+  state->status = webcrypto::Sign(state->algorithm,
+                                  state->key,
+                                  webcrypto::CryptoData(state->data),
+                                  &state->buffer);
+
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoSignReply, Passed(&passed_state)));
+}
+
+void DoVerifyReply(scoped_ptr<VerifySignatureState> state) {
+  if (state->status.IsError()) {
+    CompleteWithError(state->status, &state->result);
+  } else {
+    state->result.completeWithBoolean(state->verify_result);
+  }
+}
+
+void DoVerify(scoped_ptr<VerifySignatureState> passed_state) {
+  VerifySignatureState* state = passed_state.get();
+  state->status =
+      webcrypto::VerifySignature(state->algorithm,
+                                 state->key,
+                                 webcrypto::CryptoData(state->signature),
+                                 webcrypto::CryptoData(state->data),
+                                 &state->verify_result);
+
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoVerifyReply, Passed(&passed_state)));
+}
+
+void DoWrapKeyReply(scoped_ptr<WrapKeyState> state) {
+  CompleteWithBufferOrError(state->status, state->buffer, &state->result);
+}
+
+void DoWrapKey(scoped_ptr<WrapKeyState> passed_state) {
+  WrapKeyState* state = passed_state.get();
+  // TODO(eroman): The parameter ordering of webcrypto::WrapKey() is
+  //               inconsistent with that of blink::WebCrypto::wrapKey().
+  state->status = webcrypto::WrapKey(state->format,
+                                     state->wrapping_key,
+                                     state->key,
+                                     state->wrap_algorithm,
+                                     &state->buffer);
+
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoWrapKeyReply, Passed(&passed_state)));
+}
+
+void DoUnwrapKeyReply(scoped_ptr<UnwrapKeyState> state) {
+  CompleteWithKeyOrError(state->status, state->unwrapped_key, &state->result);
+}
+
+void DoUnwrapKey(scoped_ptr<UnwrapKeyState> passed_state) {
+  UnwrapKeyState* state = passed_state.get();
+  state->status =
+      webcrypto::UnwrapKey(state->format,
+                           webcrypto::CryptoData(state->wrapped_key),
+                           state->wrapping_key,
+                           state->unwrap_algorithm,
+                           state->unwrapped_key_algorithm,
+                           state->extractable,
+                           state->usages,
+                           &state->unwrapped_key);
+
+  state->origin_thread->PostTask(
+      FROM_HERE, base::Bind(DoUnwrapKeyReply, Passed(&passed_state)));
+}
+
 }  // namespace
 
-WebCryptoImpl::WebCryptoImpl() { webcrypto::Init(); }
-
-WebCryptoImpl::~WebCryptoImpl() {}
+WebCryptoImpl::WebCryptoImpl() {
+  webcrypto::Init();
+}
+
+WebCryptoImpl::~WebCryptoImpl() {
+}
 
 void WebCryptoImpl::encrypt(const blink::WebCryptoAlgorithm& algorithm,
                             const blink::WebCryptoKey& key,
                             const unsigned char* data,
                             unsigned int data_size,
                             blink::WebCryptoResult result) {
   DCHECK(!algorithm.isNull());
-  blink::WebArrayBuffer buffer;
-  Status status = webcrypto::Encrypt(
-      algorithm, key, webcrypto::CryptoData(data, data_size), &buffer);
-  if (status.IsError())
-    CompleteWithError(status, &result);
-  else
-    result.completeWithBuffer(buffer);
+
+  scoped_ptr<EncryptState> state(
+      new EncryptState(algorithm, key, data, data_size, result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoEncrypt, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
+  }
 }
 
 void WebCryptoImpl::decrypt(const blink::WebCryptoAlgorithm& algorithm,
                             const blink::WebCryptoKey& key,
                             const unsigned char* data,
                             unsigned int data_size,
                             blink::WebCryptoResult result) {
   DCHECK(!algorithm.isNull());
-  blink::WebArrayBuffer buffer;
-  Status status = webcrypto::Decrypt(
-      algorithm, key, webcrypto::CryptoData(data, data_size), &buffer);
-  if (status.IsError())
-    CompleteWithError(status, &result);
-  else
-    result.completeWithBuffer(buffer);
+
+  scoped_ptr<DecryptState> state(
+      new DecryptState(algorithm, key, data, data_size, result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoDecrypt, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
+  }
 }
 
 void WebCryptoImpl::digest(const blink::WebCryptoAlgorithm& algorithm,
                            const unsigned char* data,
                            unsigned int data_size,
                            blink::WebCryptoResult result) {
   DCHECK(!algorithm.isNull());
-  blink::WebArrayBuffer buffer;
-  Status status = webcrypto::Digest(
-      algorithm, webcrypto::CryptoData(data, data_size), &buffer);
-  if (status.IsError())
-    CompleteWithError(status, &result);
-  else
-    result.completeWithBuffer(buffer);
+
+  scoped_ptr<DigestState> state(new DigestState(
+      algorithm, blink::WebCryptoKey::createNull(), data, data_size, result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoDigest, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
+  }
 }
 
 void WebCryptoImpl::generateKey(const blink::WebCryptoAlgorithm& algorithm,
                                 bool extractable,
                                 blink::WebCryptoKeyUsageMask usage_mask,
                                 blink::WebCryptoResult result) {
   DCHECK(!algorithm.isNull());
-  if (IsAlgorithmAsymmetric(algorithm)) {
-    blink::WebCryptoKey public_key = blink::WebCryptoKey::createNull();
-    blink::WebCryptoKey private_key = blink::WebCryptoKey::createNull();
-    Status status = webcrypto::GenerateKeyPair(
-        algorithm, extractable, usage_mask, &public_key, &private_key);
-    if (status.IsError()) {
-      CompleteWithError(status, &result);
-    } else {
-      DCHECK(public_key.handle());
-      DCHECK(private_key.handle());
-      DCHECK_EQ(algorithm.id(), public_key.algorithm().id());
-      DCHECK_EQ(algorithm.id(), private_key.algorithm().id());
-      DCHECK_EQ(true, public_key.extractable());
-      DCHECK_EQ(extractable, private_key.extractable());
-      DCHECK_EQ(usage_mask, public_key.usages());
-      DCHECK_EQ(usage_mask, private_key.usages());
-      result.completeWithKeyPair(public_key, private_key);
-    }
-  } else {
-    blink::WebCryptoKey key = blink::WebCryptoKey::createNull();
-    Status status =
-        webcrypto::GenerateSecretKey(algorithm, extractable, usage_mask, &key);
-    if (status.IsError()) {
-      CompleteWithError(status, &result);
-    } else {
-      DCHECK(key.handle());
-      DCHECK_EQ(algorithm.id(), key.algorithm().id());
-      DCHECK_EQ(extractable, key.extractable());
-      DCHECK_EQ(usage_mask, key.usages());
-      result.completeWithKey(key);
-    }
+
+  scoped_ptr<GenerateKeyState> state(
+      new GenerateKeyState(algorithm, extractable, usage_mask, result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoGenerateKey, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
   }
 }
 
 void WebCryptoImpl::importKey(blink::WebCryptoKeyFormat format,
                               const unsigned char* key_data,
                               unsigned int key_data_size,
                               const blink::WebCryptoAlgorithm& algorithm,
                               bool extractable,
                               blink::WebCryptoKeyUsageMask usage_mask,
                               blink::WebCryptoResult result) {
-  blink::WebCryptoKey key = blink::WebCryptoKey::createNull();
-  Status status =
-      webcrypto::ImportKey(format,
-                           webcrypto::CryptoData(key_data, key_data_size),
-                           algorithm,
-                           extractable,
-                           usage_mask,
-                           &key);
-  if (status.IsError()) {
-    CompleteWithError(status, &result);
-  } else {
-    DCHECK(key.handle());
-    DCHECK(!key.algorithm().isNull());
-    DCHECK_EQ(extractable, key.extractable());
-    result.completeWithKey(key);
+  scoped_ptr<ImportKeyState> state(new ImportKeyState(format,
+                                                      key_data,
+                                                      key_data_size,
+                                                      algorithm,
+                                                      extractable,
+                                                      usage_mask,
+                                                      result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoImportKey, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
   }
 }
 
 void WebCryptoImpl::exportKey(blink::WebCryptoKeyFormat format,
                               const blink::WebCryptoKey& key,
                               blink::WebCryptoResult result) {
-  blink::WebArrayBuffer buffer;
-  Status status = webcrypto::ExportKey(format, key, &buffer);
-  if (status.IsError())
-    CompleteWithError(status, &result);
-  else
-    result.completeWithBuffer(buffer);
+  scoped_ptr<ExportKeyState> state(new ExportKeyState(format, key, result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoExportKey, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
+  }
 }
 
 void WebCryptoImpl::sign(const blink::WebCryptoAlgorithm& algorithm,
                          const blink::WebCryptoKey& key,
                          const unsigned char* data,
                          unsigned int data_size,
                          blink::WebCryptoResult result) {
-  DCHECK(!algorithm.isNull());
-  blink::WebArrayBuffer buffer;
-  Status status = webcrypto::Sign(
-      algorithm, key, webcrypto::CryptoData(data, data_size), &buffer);
-  if (status.IsError())
-    CompleteWithError(status, &result);
-  else
-    result.completeWithBuffer(buffer);
+  scoped_ptr<SignState> state(
+      new SignState(algorithm, key, data, data_size, result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoSign, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
+  }
 }
 
 void WebCryptoImpl::verifySignature(const blink::WebCryptoAlgorithm& algorithm,
                                     const blink::WebCryptoKey& key,
                                     const unsigned char* signature,
                                     unsigned int signature_size,
                                     const unsigned char* data,
                                     unsigned int data_size,
                                     blink::WebCryptoResult result) {
-  DCHECK(!algorithm.isNull());
-  bool signature_match = false;
-  Status status = webcrypto::VerifySignature(
-      algorithm,
-      key,
-      webcrypto::CryptoData(signature, signature_size),
-      webcrypto::CryptoData(data, data_size),
-      &signature_match);
-  if (status.IsError())
-    CompleteWithError(status, &result);
-  else
-    result.completeWithBoolean(signature_match);
+  scoped_ptr<VerifySignatureState> state(new VerifySignatureState(
+      algorithm, key, signature, signature_size, data, data_size, result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoVerify, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
+  }
 }
 
 void WebCryptoImpl::wrapKey(blink::WebCryptoKeyFormat format,
                             const blink::WebCryptoKey& key,
                             const blink::WebCryptoKey& wrapping_key,
                             const blink::WebCryptoAlgorithm& wrap_algorithm,
                             blink::WebCryptoResult result) {
-  blink::WebArrayBuffer buffer;
-  // TODO(eroman): Use the same parameter ordering.
-  Status status = webcrypto::WrapKey(
-      format, wrapping_key, key, wrap_algorithm, &buffer);
-  if (status.IsError())
-    CompleteWithError(status, &result);
-  else
-    result.completeWithBuffer(buffer);
+  scoped_ptr<WrapKeyState> state(
+      new WrapKeyState(format, key, wrapping_key, wrap_algorithm, result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoWrapKey, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
+  }
 }
 
 void WebCryptoImpl::unwrapKey(
     blink::WebCryptoKeyFormat format,
     const unsigned char* wrapped_key,
     unsigned wrapped_key_size,
     const blink::WebCryptoKey& wrapping_key,
     const blink::WebCryptoAlgorithm& unwrap_algorithm,
     const blink::WebCryptoAlgorithm& unwrapped_key_algorithm,
     bool extractable,
     blink::WebCryptoKeyUsageMask usages,
     blink::WebCryptoResult result) {
-  blink::WebCryptoKey key = blink::WebCryptoKey::createNull();
-  Status status =
-      webcrypto::UnwrapKey(format,
-                           webcrypto::CryptoData(wrapped_key, wrapped_key_size),
-                           wrapping_key,
-                           unwrap_algorithm,
-                           unwrapped_key_algorithm,
-                           extractable,
-                           usages,
-                           &key);
-  if (status.IsError())
-    CompleteWithError(status, &result);
-  else
-    result.completeWithKey(key);
-}
-
-bool WebCryptoImpl::digestSynchronous(
-    const blink::WebCryptoAlgorithmId algorithm_id,
-    const unsigned char* data,
-    unsigned int data_size,
-    blink::WebArrayBuffer& result) {
-  blink::WebCryptoAlgorithm algorithm =
-      blink::WebCryptoAlgorithm::adoptParamsAndCreate(algorithm_id, NULL);
-  return (webcrypto::Digest(
-              algorithm, webcrypto::CryptoData(data, data_size), &result))
-      .IsSuccess();
+  scoped_ptr<UnwrapKeyState> state(new UnwrapKeyState(format,
+                                                      wrapped_key,
+                                                      wrapped_key_size,
+                                                      wrapping_key,
+                                                      unwrap_algorithm,
+                                                      unwrapped_key_algorithm,
+                                                      extractable,
+                                                      usages,
+                                                      result));
+  if (!CryptoThreadPool::PostTask(FROM_HERE,
+                                  base::Bind(DoUnwrapKey, Passed(&state)))) {
+    CompleteWithThreadPoolError(&result);
+  }
 }
 
 blink::WebCryptoDigestor* WebCryptoImpl::createDigestor(
     blink::WebCryptoAlgorithmId algorithm_id) {
   return webcrypto::CreateDigestor(algorithm_id).release();
 }
 
 bool WebCryptoImpl::deserializeKeyForClone(
     const blink::WebCryptoKeyAlgorithm& algorithm,
     blink::WebCryptoKeyType type,
     bool extractable,
     blink::WebCryptoKeyUsageMask usages,
     const unsigned char* key_data,
     unsigned key_data_size,
     blink::WebCryptoKey& key) {
-  Status status = webcrypto::DeserializeKeyForClone(
+  // TODO(eroman): Rather than do the import immediately on the current thread,
+  //               it could defer to the crypto thread.
+  return webcrypto::DeserializeKeyForClone(
       algorithm,
       type,
       extractable,
       usages,
       webcrypto::CryptoData(key_data, key_data_size),
       &key);
-  return status.IsSuccess();
 }
 
 bool WebCryptoImpl::serializeKeyForClone(
     const blink::WebCryptoKey& key,
     blink::WebVector<unsigned char>& key_data) {
-  Status status = webcrypto::SerializeKeyForClone(key, &key_data);
-  return status.IsSuccess();
+  return webcrypto::SerializeKeyForClone(key, &key_data);
 }
 
 }  // namespace content