Add m-esr52 at 52.6.0

1 files changed, 752 insertions, 0 deletions

diff --git a/security/manager/ssl/nsNSSU2FToken.cpp b/security/manager/ssl/nsNSSU2FToken.cpp
new file mode 100644
index 000000000..f8492df02
--- /dev/null
+++ b/security/manager/ssl/nsNSSU2FToken.cpp
@@ -0,0 +1,752 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#include "nsNSSU2FToken.h"
+
+#include "CryptoBuffer.h"
+#include "mozilla/Casting.h"
+#include "nsNSSComponent.h"
+#include "pk11pub.h"
+#include "prerror.h"
+#include "secerr.h"
+#include "WebCryptoCommon.h"
+
+using namespace mozilla;
+using mozilla::dom::CreateECParamsForCurve;
+
+NS_IMPL_ISUPPORTS(nsNSSU2FToken, nsIU2FToken, nsINSSU2FToken)
+
+// Not named "security.webauth.u2f_softtoken_counter" because setting that
+// name causes the window.u2f object to disappear until preferences get
+// reloaded, as its' pref is a substring!
+#define PREF_U2F_NSSTOKEN_COUNTER "security.webauth.softtoken_counter"
+
+const nsCString nsNSSU2FToken::mSecretNickname =
+  NS_LITERAL_CSTRING("U2F_NSSTOKEN");
+const nsString nsNSSU2FToken::mVersion =
+  NS_LITERAL_STRING("U2F_V2");
+NS_NAMED_LITERAL_CSTRING(kAttestCertSubjectName, "CN=Firefox U2F Soft Token");
+
+// This U2F-compatible soft token uses FIDO U2F-compatible ECDSA keypairs
+// on the SEC_OID_SECG_EC_SECP256R1 curve. When asked to Register, it will
+// generate and return a new keypair KP, where the private component is wrapped
+// using AES-KW with the 128-bit mWrappingKey to make an opaque "key handle".
+// In other words, Register yields { KP_pub, AES-KW(KP_priv, key=mWrappingKey) }
+//
+// The value mWrappingKey is long-lived; it is persisted as part of the NSS DB
+// for the current profile. The attestation certificates that are produced are
+// ephemeral to counteract profiling. They have little use for a soft-token
+// at any rate, but are required by the specification.
+
+const uint32_t kParamLen = 32;
+const uint32_t kPublicKeyLen = 65;
+const uint32_t kWrappedKeyBufLen = 256;
+const uint32_t kWrappingKeyByteLen = 128/8;
+NS_NAMED_LITERAL_STRING(kEcAlgorithm, WEBCRYPTO_NAMED_CURVE_P256);
+
+const PRTime kOneDay = PRTime(PR_USEC_PER_SEC)
+                     * PRTime(60)  // sec
+                     * PRTime(60)  // min
+                     * PRTime(24); // hours
+const PRTime kExpirationSlack = kOneDay; // Pre-date for clock skew
+const PRTime kExpirationLife = kOneDay;
+
+static mozilla::LazyLogModule gNSSTokenLog("webauth_u2f");
+
+nsNSSU2FToken::nsNSSU2FToken()
+  : mInitialized(false)
+{}
+
+nsNSSU2FToken::~nsNSSU2FToken()
+{
+  nsNSSShutDownPreventionLock locker;
+
+  if (isAlreadyShutDown()) {
+    return;
+  }
+
+  destructorSafeDestroyNSSReference();
+  shutdown(ShutdownCalledFrom::Object);
+}
+
+void
+nsNSSU2FToken::virtualDestroyNSSReference()
+{
+  destructorSafeDestroyNSSReference();
+}
+
+void
+nsNSSU2FToken::destructorSafeDestroyNSSReference()
+{
+  mWrappingKey = nullptr;
+}
+
+/**
+ * Gets the first key with the given nickname from the given slot. Any other
+ * keys found are not returned.
+ * PK11_GetNextSymKey() should not be called on the returned key.
+ *
+ * @param aSlot Slot to search.
+ * @param aNickname Nickname the key should have.
+ * @return The first key found. nullptr if no key could be found.
+ */
+static UniquePK11SymKey
+GetSymKeyByNickname(const UniquePK11SlotInfo& aSlot,
+                    const nsCString& aNickname,
+                    const nsNSSShutDownPreventionLock&)
+{
+  MOZ_ASSERT(aSlot);
+  if (!aSlot) {
+    return nullptr;
+  }
+
+  MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
+          ("Searching for a symmetric key named %s", aNickname.get()));
+
+  UniquePK11SymKey keyListHead(
+    PK11_ListFixedKeysInSlot(aSlot.get(), const_cast<char*>(aNickname.get()),
+                             /* wincx */ nullptr));
+  if (!keyListHead) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Debug, ("Symmetric key not found."));
+    return nullptr;
+  }
+
+  // Sanity check PK11_ListFixedKeysInSlot() only returns keys with the correct
+  // nickname.
+  MOZ_ASSERT(aNickname ==
+               UniquePORTString(PK11_GetSymKeyNickname(keyListHead.get())).get());
+  MOZ_LOG(gNSSTokenLog, LogLevel::Debug, ("Symmetric key found!"));
+
+  // Free any remaining keys in the key list.
+  UniquePK11SymKey freeKey(PK11_GetNextSymKey(keyListHead.get()));
+  while (freeKey) {
+    freeKey = UniquePK11SymKey(PK11_GetNextSymKey(freeKey.get()));
+  }
+
+  return keyListHead;
+}
+
+static nsresult
+GenEcKeypair(const UniquePK11SlotInfo& aSlot,
+     /*out*/ UniqueSECKEYPrivateKey& aPrivKey,
+     /*out*/ UniqueSECKEYPublicKey& aPubKey,
+             const nsNSSShutDownPreventionLock&)
+{
+  MOZ_ASSERT(aSlot);
+  if (!aSlot) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  UniquePLArenaPool arena(PORT_NewArena(DER_DEFAULT_CHUNKSIZE));
+  if (!arena) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // Set the curve parameters; keyParams belongs to the arena memory space
+  SECItem* keyParams = CreateECParamsForCurve(kEcAlgorithm, arena.get());
+  if (!keyParams) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // Generate a key pair
+  CK_MECHANISM_TYPE mechanism = CKM_EC_KEY_PAIR_GEN;
+
+  SECKEYPublicKey* pubKeyRaw;
+  aPrivKey = UniqueSECKEYPrivateKey(
+    PK11_GenerateKeyPair(aSlot.get(), mechanism, keyParams, &pubKeyRaw,
+                         /* ephemeral */ false, false,
+                         /* wincx */ nullptr));
+  aPubKey = UniqueSECKEYPublicKey(pubKeyRaw);
+  pubKeyRaw = nullptr;
+  if (!aPrivKey.get() || !aPubKey.get()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Check that the public key has the correct length
+  if (aPubKey->u.ec.publicValue.len != kPublicKeyLen) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsNSSU2FToken::GetOrCreateWrappingKey(const UniquePK11SlotInfo& aSlot,
+                                      const nsNSSShutDownPreventionLock& locker)
+{
+  MOZ_ASSERT(aSlot);
+  if (!aSlot) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Search for an existing wrapping key. If we find it,
+  // store it for later and mark ourselves initialized.
+  mWrappingKey = GetSymKeyByNickname(aSlot, mSecretNickname, locker);
+  if (mWrappingKey) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Debug, ("U2F Soft Token Key found."));
+    mInitialized = true;
+    return NS_OK;
+  }
+
+  MOZ_LOG(gNSSTokenLog, LogLevel::Info,
+          ("No keys found. Generating new U2F Soft Token wrapping key."));
+
+  // We did not find an existing wrapping key, so we generate one in the
+  // persistent database (e.g, Token).
+  mWrappingKey = UniquePK11SymKey(
+    PK11_TokenKeyGenWithFlags(aSlot.get(), CKM_AES_KEY_GEN,
+                              /* default params */ nullptr,
+                              kWrappingKeyByteLen,
+                              /* empty keyid */ nullptr,
+                              /* flags */ CKF_WRAP | CKF_UNWRAP,
+                              /* attributes */ PK11_ATTR_TOKEN |
+                                               PK11_ATTR_PRIVATE,
+                              /* wincx */ nullptr));
+
+  if (!mWrappingKey) {
+      MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+              ("Failed to store wrapping key, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  SECStatus srv = PK11_SetSymKeyNickname(mWrappingKey.get(),
+                                         mSecretNickname.get());
+  if (srv != SECSuccess) {
+      MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+              ("Failed to set nickname, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
+          ("Key stored, nickname set to %s.", mSecretNickname.get()));
+
+  Preferences::SetUint(PREF_U2F_NSSTOKEN_COUNTER, 0);
+  return NS_OK;
+}
+
+static nsresult
+GetAttestationCertificate(const UniquePK11SlotInfo& aSlot,
+                  /*out*/ UniqueSECKEYPrivateKey& aAttestPrivKey,
+                  /*out*/ UniqueCERTCertificate& aAttestCert,
+                          const nsNSSShutDownPreventionLock& locker)
+{
+  MOZ_ASSERT(aSlot);
+  if (!aSlot) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  UniqueSECKEYPublicKey pubKey;
+
+  // Construct an ephemeral keypair for this Attestation Certificate
+  nsresult rv = GenEcKeypair(aSlot, aAttestPrivKey, pubKey, locker);
+  if (NS_FAILED(rv) || !aAttestPrivKey || !pubKey) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to gen keypair, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  // Construct the Attestation Certificate itself
+  UniqueCERTName subjectName(CERT_AsciiToName(kAttestCertSubjectName.get()));
+  if (!subjectName) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to set subject name, NSS error #%d", PORT_GetError()));
+      return NS_ERROR_FAILURE;
+  }
+
+  UniqueCERTSubjectPublicKeyInfo spki(
+    SECKEY_CreateSubjectPublicKeyInfo(pubKey.get()));
+  if (!spki) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to set SPKI, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  UniqueCERTCertificateRequest certreq(
+    CERT_CreateCertificateRequest(subjectName.get(), spki.get(), nullptr));
+  if (!certreq) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to gen CSR, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  PRTime now = PR_Now();
+  PRTime notBefore = now - kExpirationSlack;
+  PRTime notAfter = now + kExpirationLife;
+
+  UniqueCERTValidity validity(CERT_CreateValidity(notBefore, notAfter));
+  if (!validity) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to gen validity, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  unsigned long serial;
+  unsigned char* serialBytes =
+    mozilla::BitwiseCast<unsigned char*, unsigned long*>(&serial);
+  SECStatus srv = PK11_GenerateRandomOnSlot(aSlot.get(), serialBytes,
+                                            sizeof(serial));
+  if (srv != SECSuccess) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to gen serial, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+  // Ensure that the most significant bit isn't set (which would
+  // indicate a negative number, which isn't valid for serial
+  // numbers).
+  serialBytes[0] &= 0x7f;
+  // Also ensure that the least significant bit on the most
+  // significant byte is set (to prevent a leading zero byte,
+  // which also wouldn't be valid).
+  serialBytes[0] |= 0x01;
+
+  aAttestCert = UniqueCERTCertificate(
+    CERT_CreateCertificate(serial, subjectName.get(), validity.get(),
+                           certreq.get()));
+  if (!aAttestCert) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to gen certificate, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  PLArenaPool* arena = aAttestCert->arena;
+
+  srv = SECOID_SetAlgorithmID(arena, &aAttestCert->signature,
+                              SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE,
+                              /* wincx */ nullptr);
+  if (srv != SECSuccess) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Set version to X509v3.
+  *(aAttestCert->version.data) = SEC_CERTIFICATE_VERSION_3;
+  aAttestCert->version.len = 1;
+
+  SECItem innerDER = { siBuffer, nullptr, 0 };
+  if (!SEC_ASN1EncodeItem(arena, &innerDER, aAttestCert.get(),
+                          SEC_ASN1_GET(CERT_CertificateTemplate))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  SECItem* signedCert = PORT_ArenaZNew(arena, SECItem);
+  if (!signedCert) {
+    return NS_ERROR_FAILURE;
+  }
+
+  srv = SEC_DerSignData(arena, signedCert, innerDER.data, innerDER.len,
+                        aAttestPrivKey.get(),
+                        SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
+  if (srv != SECSuccess) {
+    return NS_ERROR_FAILURE;
+  }
+  aAttestCert->derCert = *signedCert;
+
+  MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
+          ("U2F Soft Token attestation certificate generated."));
+  return NS_OK;
+}
+
+// Set up the context for the soft U2F Token. This is called by NSS
+// initialization.
+NS_IMETHODIMP
+nsNSSU2FToken::Init()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mInitialized);
+  if (mInitialized) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsNSSShutDownPreventionLock locker;
+  if (isAlreadyShutDown()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  UniquePK11SlotInfo slot(PK11_GetInternalKeySlot());
+  MOZ_ASSERT(slot.get());
+
+  // Search for an existing wrapping key, or create one.
+  nsresult rv = GetOrCreateWrappingKey(slot, locker);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  mInitialized = true;
+  MOZ_LOG(gNSSTokenLog, LogLevel::Debug, ("U2F Soft Token initialized."));
+  return NS_OK;
+}
+
+// Convert a Private Key object into an opaque key handle, using AES Key Wrap
+// and aWrappingKey to convert aPrivKey.
+static UniqueSECItem
+KeyHandleFromPrivateKey(const UniquePK11SlotInfo& aSlot,
+                        const UniquePK11SymKey& aWrappingKey,
+                        const UniqueSECKEYPrivateKey& aPrivKey,
+                        const nsNSSShutDownPreventionLock&)
+{
+  MOZ_ASSERT(aSlot);
+  MOZ_ASSERT(aWrappingKey);
+  MOZ_ASSERT(aPrivKey);
+  if (!aSlot || !aWrappingKey || !aPrivKey) {
+    return nullptr;
+  }
+
+  UniqueSECItem wrappedKey(SECITEM_AllocItem(/* default arena */ nullptr,
+                                             /* no buffer */ nullptr,
+                                             kWrappedKeyBufLen));
+  if (!wrappedKey) {
+      MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+              ("Failed to allocate memory, NSS error #%d", PORT_GetError()));
+    return nullptr;
+  }
+
+  UniqueSECItem param(PK11_ParamFromIV(CKM_NSS_AES_KEY_WRAP_PAD,
+                                       /* default IV */ nullptr ));
+
+  SECStatus srv = PK11_WrapPrivKey(aSlot.get(), aWrappingKey.get(),
+                                   aPrivKey.get(), CKM_NSS_AES_KEY_WRAP_PAD,
+                                   param.get(), wrappedKey.get(),
+                                   /* wincx */ nullptr);
+  if (srv != SECSuccess) {
+      MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+              ("Failed to wrap U2F key, NSS error #%d", PORT_GetError()));
+    return nullptr;
+  }
+
+  return wrappedKey;
+}
+
+// Convert an opaque key handle aKeyHandle back into a Private Key object, using
+// aWrappingKey and the AES Key Wrap algorithm.
+static UniqueSECKEYPrivateKey
+PrivateKeyFromKeyHandle(const UniquePK11SlotInfo& aSlot,
+                        const UniquePK11SymKey& aWrappingKey,
+                        uint8_t* aKeyHandle, uint32_t aKeyHandleLen,
+                        const nsNSSShutDownPreventionLock&)
+{
+  MOZ_ASSERT(aSlot);
+  MOZ_ASSERT(aWrappingKey);
+  MOZ_ASSERT(aKeyHandle);
+  if (!aSlot || !aWrappingKey || !aKeyHandle) {
+    return nullptr;
+  }
+
+  ScopedAutoSECItem pubKey(kPublicKeyLen);
+
+  ScopedAutoSECItem keyHandleItem(aKeyHandleLen);
+  memcpy(keyHandleItem.data, aKeyHandle, keyHandleItem.len);
+
+  UniqueSECItem param(PK11_ParamFromIV(CKM_NSS_AES_KEY_WRAP_PAD,
+                                       /* default IV */ nullptr ));
+
+  CK_ATTRIBUTE_TYPE usages[] = { CKA_SIGN };
+  int usageCount = 1;
+
+  UniqueSECKEYPrivateKey unwrappedKey(
+    PK11_UnwrapPrivKey(aSlot.get(), aWrappingKey.get(), CKM_NSS_AES_KEY_WRAP_PAD,
+                       param.get(), &keyHandleItem,
+                       /* no nickname */ nullptr,
+                       /* discard pubkey */ &pubKey,
+                       /* not permanent */ false,
+                       /* non-exportable */ true,
+                       CKK_EC, usages, usageCount,
+                       /* wincx */ nullptr));
+  if (!unwrappedKey) {
+    // Not our key.
+    MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
+            ("Could not unwrap key handle, NSS Error #%d", PORT_GetError()));
+    return nullptr;
+  }
+
+  return unwrappedKey;
+}
+
+// Return whether the provided version is supported by this token.
+NS_IMETHODIMP
+nsNSSU2FToken::IsCompatibleVersion(const nsAString& aVersion, bool* aResult)
+{
+  NS_ENSURE_ARG_POINTER(aResult);
+  MOZ_ASSERT(mInitialized);
+  *aResult = (mVersion == aVersion);
+  return NS_OK;
+}
+
+// IsRegistered determines if the provided key handle is usable by this token.
+NS_IMETHODIMP
+nsNSSU2FToken::IsRegistered(uint8_t* aKeyHandle, uint32_t aKeyHandleLen,
+                            bool* aResult)
+{
+  NS_ENSURE_ARG_POINTER(aKeyHandle);
+  NS_ENSURE_ARG_POINTER(aResult);
+
+  if (!NS_IsMainThread()) {
+    NS_ERROR("nsNSSU2FToken::IsRegistered called off the main thread");
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  nsNSSShutDownPreventionLock locker;
+  if (isAlreadyShutDown()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  MOZ_ASSERT(mInitialized);
+  if (!mInitialized) {
+    return NS_ERROR_FAILURE;
+  }
+
+  UniquePK11SlotInfo slot(PK11_GetInternalSlot());
+  MOZ_ASSERT(slot.get());
+
+  // Decode the key handle
+  UniqueSECKEYPrivateKey privKey = PrivateKeyFromKeyHandle(slot, mWrappingKey,
+                                                           aKeyHandle,
+                                                           aKeyHandleLen,
+                                                           locker);
+  *aResult = (privKey.get() != nullptr);
+  return NS_OK;
+}
+
+// A U2F Register operation causes a new key pair to be generated by the token.
+// The token then returns the public key of the key pair, and a handle to the
+// private key, which is a fancy way of saying "key wrapped private key", as
+// well as the generated attestation certificate and a signature using that
+// certificate's private key.
+//
+// The KeyHandleFromPrivateKey and PrivateKeyFromKeyHandle methods perform
+// the actual key wrap/unwrap operations.
+//
+// The format of the return registration data is as follows:
+//
+// Bytes  Value
+// 1      0x05
+// 65     public key
+// 1      key handle length
+// *      key handle
+// ASN.1  attestation certificate
+// *      attestation signature
+//
+NS_IMETHODIMP
+nsNSSU2FToken::Register(uint8_t* aApplication,
+                        uint32_t aApplicationLen,
+                        uint8_t* aChallenge,
+                        uint32_t aChallengeLen,
+                        uint8_t** aRegistration,
+                        uint32_t* aRegistrationLen)
+{
+  NS_ENSURE_ARG_POINTER(aApplication);
+  NS_ENSURE_ARG_POINTER(aChallenge);
+  NS_ENSURE_ARG_POINTER(aRegistration);
+  NS_ENSURE_ARG_POINTER(aRegistrationLen);
+
+  if (!NS_IsMainThread()) {
+    NS_ERROR("nsNSSU2FToken::Register called off the main thread");
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  nsNSSShutDownPreventionLock locker;
+  if (isAlreadyShutDown()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  MOZ_ASSERT(mInitialized);
+  if (!mInitialized) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // We should already have a wrapping key
+  MOZ_ASSERT(mWrappingKey);
+
+  UniquePK11SlotInfo slot(PK11_GetInternalSlot());
+  MOZ_ASSERT(slot.get());
+
+  // Construct a one-time-use Attestation Certificate
+  UniqueSECKEYPrivateKey attestPrivKey;
+  UniqueCERTCertificate attestCert;
+  nsresult rv = GetAttestationCertificate(slot, attestPrivKey, attestCert,
+                                          locker);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return NS_ERROR_FAILURE;
+  }
+  MOZ_ASSERT(attestCert);
+  MOZ_ASSERT(attestPrivKey);
+
+  // Generate a new keypair; the private will be wrapped into a Key Handle
+  UniqueSECKEYPrivateKey privKey;
+  UniqueSECKEYPublicKey pubKey;
+  rv = GenEcKeypair(slot, privKey, pubKey, locker);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // The key handle will be the result of keywrap(privKey, key=mWrappingKey)
+  UniqueSECItem keyHandleItem = KeyHandleFromPrivateKey(slot, mWrappingKey,
+                                                        privKey, locker);
+  if (!keyHandleItem.get()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Sign the challenge using the Attestation privkey (from attestCert)
+  mozilla::dom::CryptoBuffer signedDataBuf;
+  if (!signedDataBuf.SetCapacity(1 + aApplicationLen + aChallengeLen +
+                                 keyHandleItem->len + kPublicKeyLen,
+                                 mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // It's OK to ignore the return values here because we're writing into
+  // pre-allocated space
+  signedDataBuf.AppendElement(0x00, mozilla::fallible);
+  signedDataBuf.AppendElements(aApplication, aApplicationLen, mozilla::fallible);
+  signedDataBuf.AppendElements(aChallenge, aChallengeLen, mozilla::fallible);
+  signedDataBuf.AppendSECItem(keyHandleItem.get());
+  signedDataBuf.AppendSECItem(pubKey->u.ec.publicValue);
+
+  ScopedAutoSECItem signatureItem;
+  SECStatus srv = SEC_SignData(&signatureItem, signedDataBuf.Elements(),
+                               signedDataBuf.Length(), attestPrivKey.get(),
+                               SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
+  if (srv != SECSuccess) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Signature failure: %d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  // Serialize the registration data
+  mozilla::dom::CryptoBuffer registrationBuf;
+  if (!registrationBuf.SetCapacity(1 + kPublicKeyLen + 1 + keyHandleItem->len +
+                                   attestCert.get()->derCert.len +
+                                   signatureItem.len, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  registrationBuf.AppendElement(0x05, mozilla::fallible);
+  registrationBuf.AppendSECItem(pubKey->u.ec.publicValue);
+  registrationBuf.AppendElement(keyHandleItem->len, mozilla::fallible);
+  registrationBuf.AppendSECItem(keyHandleItem.get());
+  registrationBuf.AppendSECItem(attestCert.get()->derCert);
+  registrationBuf.AppendSECItem(signatureItem);
+  if (!registrationBuf.ToNewUnsignedBuffer(aRegistration, aRegistrationLen)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+// A U2F Sign operation creates a signature over the "param" arguments (plus
+// some other stuff) using the private key indicated in the key handle argument.
+//
+// The format of the signed data is as follows:
+//
+//  32    Application parameter
+//  1     User presence (0x01)
+//  4     Counter
+//  32    Challenge parameter
+//
+// The format of the signature data is as follows:
+//
+//  1     User presence
+//  4     Counter
+//  *     Signature
+//
+NS_IMETHODIMP
+nsNSSU2FToken::Sign(uint8_t* aApplication, uint32_t aApplicationLen,
+                    uint8_t* aChallenge, uint32_t aChallengeLen,
+                    uint8_t* aKeyHandle, uint32_t aKeyHandleLen,
+                    uint8_t** aSignature, uint32_t* aSignatureLen)
+{
+  NS_ENSURE_ARG_POINTER(aApplication);
+  NS_ENSURE_ARG_POINTER(aChallenge);
+  NS_ENSURE_ARG_POINTER(aKeyHandle);
+  NS_ENSURE_ARG_POINTER(aKeyHandleLen);
+  NS_ENSURE_ARG_POINTER(aSignature);
+  NS_ENSURE_ARG_POINTER(aSignatureLen);
+
+  if (!NS_IsMainThread()) {
+    NS_ERROR("nsNSSU2FToken::Sign called off the main thread");
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  nsNSSShutDownPreventionLock locker;
+  if (isAlreadyShutDown()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  MOZ_ASSERT(mInitialized);
+  if (!mInitialized) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  MOZ_ASSERT(mWrappingKey);
+
+  UniquePK11SlotInfo slot(PK11_GetInternalSlot());
+  MOZ_ASSERT(slot.get());
+
+  if ((aChallengeLen != kParamLen) || (aApplicationLen != kParamLen)) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Parameter lengths are wrong! challenge=%d app=%d expected=%d",
+            aChallengeLen, aApplicationLen, kParamLen));
+
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  // Decode the key handle
+  UniqueSECKEYPrivateKey privKey = PrivateKeyFromKeyHandle(slot, mWrappingKey,
+                                                           aKeyHandle,
+                                                           aKeyHandleLen,
+                                                           locker);
+  if (!privKey.get()) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Couldn't get the priv key!"));
+    return NS_ERROR_FAILURE;
+  }
+
+  // Increment the counter and turn it into a SECItem
+  uint32_t counter = Preferences::GetUint(PREF_U2F_NSSTOKEN_COUNTER) + 1;
+  Preferences::SetUint(PREF_U2F_NSSTOKEN_COUNTER, counter);
+  ScopedAutoSECItem counterItem(4);
+  counterItem.data[0] = (counter >> 24) & 0xFF;
+  counterItem.data[1] = (counter >> 16) & 0xFF;
+  counterItem.data[2] = (counter >>  8) & 0xFF;
+  counterItem.data[3] = (counter >>  0) & 0xFF;
+
+  // Compute the signature
+  mozilla::dom::CryptoBuffer signedDataBuf;
+  if (!signedDataBuf.SetCapacity(1 + 4 + (2 * kParamLen), mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // It's OK to ignore the return values here because we're writing into
+  // pre-allocated space
+  signedDataBuf.AppendElements(aApplication, aApplicationLen, mozilla::fallible);
+  signedDataBuf.AppendElement(0x01, mozilla::fallible);
+  signedDataBuf.AppendSECItem(counterItem);
+  signedDataBuf.AppendElements(aChallenge, aChallengeLen, mozilla::fallible);
+
+  ScopedAutoSECItem signatureItem;
+  SECStatus srv = SEC_SignData(&signatureItem, signedDataBuf.Elements(),
+                               signedDataBuf.Length(), privKey.get(),
+                               SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
+  if (srv != SECSuccess) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Signature failure: %d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  // Assemble the signature data into a buffer for return
+  mozilla::dom::CryptoBuffer signatureBuf;
+  if (!signatureBuf.SetCapacity(1 + counterItem.len + signatureItem.len,
+                                mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // It's OK to ignore the return values here because we're writing into
+  // pre-allocated space
+  signatureBuf.AppendElement(0x01, mozilla::fallible);
+  signatureBuf.AppendSECItem(counterItem);
+  signatureBuf.AppendSECItem(signatureItem);
+
+  if (!signatureBuf.ToNewUnsignedBuffer(aSignature, aSignatureLen)) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}