1 files changed, 36 insertions, 2 deletions
diff --git a/crypto/ec_private_key_nss.cc b/crypto/ec_private_key_nss.cc
index c6c4763..9bb9df1 100644
--- a/crypto/ec_private_key_nss.cc
+++ b/crypto/ec_private_key_nss.cc
@@ -15,6 +15,7 @@ extern "C" {
 #include <pk11pub.h>
 #include <secmod.h>
 
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "crypto/nss_util.h"
@@ -24,6 +25,34 @@ extern "C" {
 
 namespace {
 
+PK11SlotInfo* GetKeySlot() {
+  return crypto::GetPublicNSSKeySlot();
+}
+
+class EllipticCurveSupportChecker {
+ public:
+  EllipticCurveSupportChecker() {
+    // NOTE: we can do this check here only because we use the NSS internal
+    // slot.  If we support other slots in the future, checking whether they
+    // support ECDSA may block NSS, and the value may also change as devices are
+    // inserted/removed, so we would need to re-check on every use.
+    crypto::EnsureNSSInit();
+    crypto::ScopedPK11Slot slot(GetKeySlot());
+    supported_ = PK11_DoesMechanism(slot.get(), CKM_EC_KEY_PAIR_GEN) &&
+        PK11_DoesMechanism(slot.get(), CKM_ECDSA);
+  }
+
+  bool Supported() {
+    return supported_;
+  }
+
+ private:
+  bool supported_;
+};
+
+static base::LazyInstance<EllipticCurveSupportChecker>::Leaky
+    g_elliptic_curve_supported = LAZY_INSTANCE_INITIALIZER;
+
 // Copied from rsa_private_key_nss.cc.
 static bool ReadAttribute(SECKEYPrivateKey* key,
                           CK_ATTRIBUTE_TYPE type,
@@ -53,6 +82,11 @@ ECPrivateKey::~ECPrivateKey() {
 }
 
 // static
+bool ECPrivateKey::IsSupported() {
+  return g_elliptic_curve_supported.Get().Supported();
+}
+
+// static
 ECPrivateKey* ECPrivateKey::Create() {
   return CreateWithParams(PR_FALSE /* not permanent */,
                           PR_FALSE /* not sensitive */);
@@ -114,7 +148,7 @@ bool ECPrivateKey::ImportFromEncryptedPrivateKeyInfo(
     bool sensitive,
     SECKEYPrivateKey** key,
     SECKEYPublicKey** public_key) {
-  ScopedPK11Slot slot(GetPublicNSSKeySlot());
+  ScopedPK11Slot slot(GetKeySlot());
   if (!slot.get())
     return false;
 
@@ -247,7 +281,7 @@ ECPrivateKey* ECPrivateKey::CreateWithParams(bool permanent,
 
   scoped_ptr<ECPrivateKey> result(new ECPrivateKey);
 
-  ScopedPK11Slot slot(GetPrivateNSSKeySlot());
+  ScopedPK11Slot slot(GetKeySlot());
   if (!slot.get())
     return NULL;