Adding upstream version 115.8.0esr.upstream/115.8.0esr

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

1 files changed, 1031 insertions, 0 deletions

diff --git a/dom/webauthn/U2FSoftTokenTransport.cpp b/dom/webauthn/U2FSoftTokenTransport.cpp
new file mode 100644
index 0000000000..3b2f2a6231
--- /dev/null
+++ b/dom/webauthn/U2FSoftTokenTransport.cpp
@@ -0,0 +1,1031 @@
+/* -*- 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 "CtapResults.h"
+#include "WebAuthnCoseIdentifiers.h"
+#include "WebAuthnEnumStrings.h"
+#include "U2FSoftTokenTransport.h"
+#include "mozilla/dom/WebAuthnUtil.h"
+#include "CryptoBuffer.h"
+#include "mozilla/Base64.h"
+#include "mozilla/Casting.h"
+#include "mozilla/Preferences.h"
+#include "nsNSSComponent.h"
+#include "nsThreadUtils.h"
+#include "pk11pub.h"
+#include "prerror.h"
+#include "secerr.h"
+#include "WebCryptoCommon.h"
+
+#define PREF_U2F_NSSTOKEN_COUNTER "security.webauth.softtoken_counter"
+
+namespace mozilla::dom {
+
+using namespace mozilla;
+using mozilla::dom::CreateECParamsForCurve;
+
+const nsCString U2FSoftTokenTransport::mSecretNickname = "U2F_NSSTOKEN"_ns;
+
+namespace {
+constexpr auto kAttestCertSubjectName = "CN=Firefox U2F Soft Token"_ns;
+
+// 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;
+const uint32_t kSaltByteLen = 64 / 8;
+const uint32_t kVersion1KeyHandleLen = 162;
+constexpr auto kEcAlgorithm =
+    NS_LITERAL_STRING_FROM_CSTRING(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("webauthn_softtoken");
+
+enum SoftTokenHandle {
+  Version1 = 0,
+};
+
+}  // namespace
+
+NS_IMPL_ISUPPORTS(U2FSoftTokenTransport, nsIWebAuthnTransport)
+
+U2FSoftTokenTransport::U2FSoftTokenTransport(uint32_t aCounter)
+    : mInitialized(false), mCounter(aCounter), mController(nullptr) {}
+
+NS_IMETHODIMP
+U2FSoftTokenTransport::GetController(nsIWebAuthnController** aController) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+U2FSoftTokenTransport::SetController(nsIWebAuthnController* aController) {
+  mController = aController;
+  return NS_OK;
+}
+
+/**
+ * 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) {
+  MOZ_ASSERT(aSlot);
+  if (NS_WARN_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 (NS_WARN_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) {
+  MOZ_ASSERT(aSlot);
+  if (NS_WARN_IF(!aSlot)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  UniquePLArenaPool arena(PORT_NewArena(DER_DEFAULT_CHUNKSIZE));
+  if (NS_WARN_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 (NS_WARN_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 (NS_WARN_IF(!aPrivKey.get() || !aPubKey.get())) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Check that the public key has the correct length
+  if (NS_WARN_IF(aPubKey->u.ec.publicValue.len != kPublicKeyLen)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+nsresult U2FSoftTokenTransport::GetOrCreateWrappingKey(
+    const UniquePK11SlotInfo& aSlot) {
+  MOZ_ASSERT(aSlot);
+  if (NS_WARN_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);
+  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 (NS_WARN_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 (NS_WARN_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()));
+
+  GetMainThreadSerialEventTarget()->Dispatch(NS_NewRunnableFunction(
+      "dom::U2FSoftTokenTransport::GetOrCreateWrappingKey", []() {
+        MOZ_ASSERT(NS_IsMainThread());
+        Preferences::SetUint(PREF_U2F_NSSTOKEN_COUNTER, 0);
+      }));
+
+  return NS_OK;
+}
+
+static nsresult GetAttestationCertificate(
+    const UniquePK11SlotInfo& aSlot,
+    /*out*/ UniqueSECKEYPrivateKey& aAttestPrivKey,
+    /*out*/ UniqueCERTCertificate& aAttestCert) {
+  MOZ_ASSERT(aSlot);
+  if (NS_WARN_IF(!aSlot)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  UniqueSECKEYPublicKey pubKey;
+
+  // Construct an ephemeral keypair for this Attestation Certificate
+  nsresult rv = GenEcKeypair(aSlot, aAttestPrivKey, pubKey);
+  if (NS_WARN_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 (NS_WARN_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 (NS_WARN_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 (NS_WARN_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 (NS_WARN_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 (NS_WARN_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;
+
+  // NB: CERTCertificates created with CERT_CreateCertificate are not safe to
+  // use with other NSS functions like CERT_DupCertificate.
+  // The strategy here is to create a tbsCertificate ("to-be-signed
+  // certificate"), encode it, and sign it, resulting in a signed DER
+  // certificate that can be decoded into a CERTCertificate.
+  UniqueCERTCertificate tbsCertificate(CERT_CreateCertificate(
+      serial, subjectName.get(), validity.get(), certreq.get()));
+  if (NS_WARN_IF(!tbsCertificate)) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to gen certificate, NSS error #%d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  PLArenaPool* arena = tbsCertificate->arena;
+
+  srv = SECOID_SetAlgorithmID(arena, &tbsCertificate->signature,
+                              SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE,
+                              /* wincx */ nullptr);
+  if (NS_WARN_IF(srv != SECSuccess)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Set version to X509v3.
+  *(tbsCertificate->version.data) = SEC_CERTIFICATE_VERSION_3;
+  tbsCertificate->version.len = 1;
+
+  SECItem innerDER = {siBuffer, nullptr, 0};
+  if (NS_WARN_IF(!SEC_ASN1EncodeItem(arena, &innerDER, tbsCertificate.get(),
+                                     SEC_ASN1_GET(CERT_CertificateTemplate)))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  SECItem* certDer = PORT_ArenaZNew(arena, SECItem);
+  if (NS_WARN_IF(!certDer)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  srv = SEC_DerSignData(arena, certDer, innerDER.data, innerDER.len,
+                        aAttestPrivKey.get(),
+                        SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
+  if (NS_WARN_IF(srv != SECSuccess)) {
+    return NS_ERROR_FAILURE;
+  }
+  aAttestCert = UniqueCERTCertificate(CERT_NewTempCertificate(
+      CERT_GetDefaultCertDB(), certDer, nullptr, false, true));
+  if (NS_WARN_IF(!aAttestCert)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  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.
+nsresult U2FSoftTokenTransport::Init() {
+  // If we've already initialized, just return.
+  if (mInitialized) {
+    return NS_OK;
+  }
+
+  UniquePK11SlotInfo slot(PK11_GetInternalKeySlot());
+  MOZ_ASSERT(slot.get());
+
+  // Search for an existing wrapping key, or create one.
+  nsresult rv = GetOrCreateWrappingKey(slot);
+  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
+// with the long-lived aPersistentKey mixed with aAppParam to convert aPrivKey.
+// The key handle's format is version || saltLen || salt || wrappedPrivateKey
+static UniqueSECItem KeyHandleFromPrivateKey(
+    const UniquePK11SlotInfo& aSlot, const UniquePK11SymKey& aPersistentKey,
+    uint8_t* aAppParam, uint32_t aAppParamLen,
+    const UniqueSECKEYPrivateKey& aPrivKey) {
+  MOZ_ASSERT(aSlot);
+  MOZ_ASSERT(aPersistentKey);
+  MOZ_ASSERT(aAppParam);
+  MOZ_ASSERT(aPrivKey);
+  if (NS_WARN_IF(!aSlot || !aPersistentKey || !aPrivKey || !aAppParam)) {
+    return nullptr;
+  }
+
+  // Generate a random salt
+  uint8_t saltParam[kSaltByteLen];
+  SECStatus srv =
+      PK11_GenerateRandomOnSlot(aSlot.get(), saltParam, sizeof(saltParam));
+  if (NS_WARN_IF(srv != SECSuccess)) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to generate a salt, NSS error #%d", PORT_GetError()));
+    return nullptr;
+  }
+
+  // Prepare the HKDF (https://tools.ietf.org/html/rfc5869)
+  CK_NSS_HKDFParams hkdfParams = {true, saltParam, sizeof(saltParam),
+                                  true, aAppParam, aAppParamLen};
+  SECItem kdfParams = {siBuffer, (unsigned char*)&hkdfParams,
+                       sizeof(hkdfParams)};
+
+  // Derive a wrapping key from aPersistentKey, the salt, and the aAppParam.
+  // CKM_AES_KEY_GEN and CKA_WRAP are key type and usage attributes of the
+  // derived symmetric key and don't matter because we ignore them anyway.
+  UniquePK11SymKey wrapKey(
+      PK11_Derive(aPersistentKey.get(), CKM_NSS_HKDF_SHA256, &kdfParams,
+                  CKM_AES_KEY_GEN, CKA_WRAP, kWrappingKeyByteLen));
+  if (NS_WARN_IF(!wrapKey.get())) {
+    MOZ_LOG(
+        gNSSTokenLog, LogLevel::Warning,
+        ("Failed to derive a wrapping key, NSS error #%d", PORT_GetError()));
+    return nullptr;
+  }
+
+  UniqueSECItem wrappedKey(::SECITEM_AllocItem(/* default arena */ nullptr,
+                                               /* no buffer */ nullptr,
+                                               kWrappedKeyBufLen));
+  if (NS_WARN_IF(!wrappedKey)) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
+    return nullptr;
+  }
+
+  UniqueSECItem param(PK11_ParamFromIV(CKM_NSS_AES_KEY_WRAP_PAD,
+                                       /* default IV */ nullptr));
+
+  srv =
+      PK11_WrapPrivKey(aSlot.get(), wrapKey.get(), aPrivKey.get(),
+                       CKM_NSS_AES_KEY_WRAP_PAD, param.get(), wrappedKey.get(),
+                       /* wincx */ nullptr);
+  if (NS_WARN_IF(srv != SECSuccess)) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Failed to wrap U2F key, NSS error #%d", PORT_GetError()));
+    return nullptr;
+  }
+
+  // Concatenate the salt and the wrapped Private Key together
+  mozilla::dom::CryptoBuffer keyHandleBuf;
+  if (NS_WARN_IF(!keyHandleBuf.SetCapacity(
+          wrappedKey.get()->len + sizeof(saltParam) + 2, mozilla::fallible))) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
+    return nullptr;
+  }
+
+  // It's OK to ignore the return values here because we're writing into
+  // pre-allocated space
+  (void)keyHandleBuf.AppendElement(SoftTokenHandle::Version1,
+                                   mozilla::fallible);
+  (void)keyHandleBuf.AppendElement(sizeof(saltParam), mozilla::fallible);
+  (void)keyHandleBuf.AppendElements(saltParam, sizeof(saltParam),
+                                    mozilla::fallible);
+  keyHandleBuf.AppendSECItem(wrappedKey.get());
+
+  UniqueSECItem keyHandle(::SECITEM_AllocItem(nullptr, nullptr, 0));
+  if (NS_WARN_IF(!keyHandle)) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
+    return nullptr;
+  }
+
+  if (NS_WARN_IF(!keyHandleBuf.ToSECItem(/* default arena */ nullptr,
+                                         keyHandle.get()))) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
+    return nullptr;
+  }
+  return keyHandle;
+}
+
+// Convert an opaque key handle aKeyHandle back into a Private Key object, using
+// the long-lived aPersistentKey mixed with aAppParam and the AES Key Wrap
+// algorithm.
+static UniqueSECKEYPrivateKey PrivateKeyFromKeyHandle(
+    const UniquePK11SlotInfo& aSlot, const UniquePK11SymKey& aPersistentKey,
+    uint8_t* aKeyHandle, uint32_t aKeyHandleLen, uint8_t* aAppParam,
+    uint32_t aAppParamLen) {
+  MOZ_ASSERT(aSlot);
+  MOZ_ASSERT(aPersistentKey);
+  MOZ_ASSERT(aKeyHandle);
+  MOZ_ASSERT(aAppParam);
+  MOZ_ASSERT(aAppParamLen == SHA256_LENGTH);
+  if (NS_WARN_IF(!aSlot || !aPersistentKey || !aKeyHandle || !aAppParam ||
+                 aAppParamLen != SHA256_LENGTH)) {
+    return nullptr;
+  }
+
+  // As we only support one key format ourselves (right now), fail early if
+  // we aren't that length
+  if (NS_WARN_IF(aKeyHandleLen != kVersion1KeyHandleLen)) {
+    return nullptr;
+  }
+
+  if (NS_WARN_IF(aKeyHandle[0] != SoftTokenHandle::Version1)) {
+    // Unrecognized version
+    return nullptr;
+  }
+
+  uint8_t saltLen = aKeyHandle[1];
+  uint8_t* saltPtr = aKeyHandle + 2;
+  if (NS_WARN_IF(saltLen != kSaltByteLen)) {
+    return nullptr;
+  }
+
+  // Prepare the HKDF (https://tools.ietf.org/html/rfc5869)
+  CK_NSS_HKDFParams hkdfParams = {true, saltPtr,   saltLen,
+                                  true, aAppParam, aAppParamLen};
+  SECItem kdfParams = {siBuffer, (unsigned char*)&hkdfParams,
+                       sizeof(hkdfParams)};
+
+  // Derive a wrapping key from aPersistentKey, the salt, and the aAppParam.
+  // CKM_AES_KEY_GEN and CKA_WRAP are key type and usage attributes of the
+  // derived symmetric key and don't matter because we ignore them anyway.
+  UniquePK11SymKey wrapKey(
+      PK11_Derive(aPersistentKey.get(), CKM_NSS_HKDF_SHA256, &kdfParams,
+                  CKM_AES_KEY_GEN, CKA_WRAP, kWrappingKeyByteLen));
+  if (NS_WARN_IF(!wrapKey.get())) {
+    MOZ_LOG(
+        gNSSTokenLog, LogLevel::Warning,
+        ("Failed to derive a wrapping key, NSS error #%d", PORT_GetError()));
+    return nullptr;
+  }
+
+  uint8_t wrappedLen = aKeyHandleLen - saltLen - 2;
+  uint8_t* wrappedPtr = aKeyHandle + saltLen + 2;
+
+  ScopedAutoSECItem wrappedKeyItem(wrappedLen);
+  memcpy(wrappedKeyItem.data, wrappedPtr, wrappedKeyItem.len);
+
+  ScopedAutoSECItem pubKey(kPublicKeyLen);
+
+  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(), wrapKey.get(), CKM_NSS_AES_KEY_WRAP_PAD,
+                         param.get(), &wrappedKeyItem,
+                         /* no nickname */ nullptr,
+                         /* discard pubkey */ &pubKey,
+                         /* not permanent */ false,
+                         /* non-exportable */ true, CKK_EC, usages, usageCount,
+                         /* wincx */ nullptr));
+  if (NS_WARN_IF(!unwrappedKey)) {
+    // Not our key.
+    MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
+            ("Could not unwrap key handle, NSS Error #%d", PORT_GetError()));
+    return nullptr;
+  }
+
+  return unwrappedKey;
+}
+
+// IsRegistered determines if the provided key handle is usable by this token.
+nsresult U2FSoftTokenTransport::IsRegistered(
+    const nsTArray<uint8_t>& aKeyHandle, const nsTArray<uint8_t>& aAppParam,
+    bool& aResult) {
+  if (!mInitialized) {
+    nsresult rv = Init();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  UniquePK11SlotInfo slot(PK11_GetInternalSlot());
+  MOZ_ASSERT(slot.get());
+
+  // Decode the key handle
+  UniqueSECKEYPrivateKey privKey = PrivateKeyFromKeyHandle(
+      slot, mWrappingKey, const_cast<uint8_t*>(aKeyHandle.Elements()),
+      aKeyHandle.Length(), const_cast<uint8_t*>(aAppParam.Elements()),
+      aAppParam.Length());
+  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
+U2FSoftTokenTransport::MakeCredential(uint64_t aTransactionId,
+                                      uint64_t _aBrowsingContextId,
+                                      nsICtapRegisterArgs* args) {
+  nsresult rv;
+
+  if (!mInitialized) {
+    rv = Init();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  if (NS_WARN_IF(!args)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  bool requireResidentKey = false;
+  nsString residentKey;
+  rv = args->GetResidentKey(residentKey);
+  if (NS_SUCCEEDED(rv) && residentKey.EqualsLiteral(
+                              MOZ_WEBAUTHN_RESIDENT_KEY_REQUIREMENT_REQUIRED)) {
+    requireResidentKey = true;
+  }
+
+  bool requireUserVerification = false;
+  nsString userVerification;
+  // Bug 1737205 will make this infallible
+  rv = args->GetUserVerification(userVerification);
+  if (NS_SUCCEEDED(rv)) {
+    requireUserVerification = userVerification.EqualsLiteral(
+        MOZ_WEBAUTHN_USER_VERIFICATION_REQUIREMENT_REQUIRED);
+  }
+
+  bool requirePlatformAttachment = false;
+  nsString authenticatorAttachment;
+  // Bug 1737205 will make this infallible
+  rv = args->GetAuthenticatorAttachment(authenticatorAttachment);
+  if (NS_SUCCEEDED(rv) && authenticatorAttachment.EqualsLiteral(
+                              MOZ_WEBAUTHN_AUTHENTICATOR_ATTACHMENT_PLATFORM)) {
+    requirePlatformAttachment = true;
+  }
+
+  // The U2F softtoken neither supports resident keys or
+  // user verification, nor is it a platform authenticator.
+  if (requireResidentKey || requireUserVerification ||
+      requirePlatformAttachment) {
+    return NS_ERROR_DOM_NOT_ALLOWED_ERR;
+  }
+
+  bool noneAttestationRequested = false;
+  nsString attestationConveyancePreference;
+  rv =
+      args->GetAttestationConveyancePreference(attestationConveyancePreference);
+  if (NS_SUCCEEDED(rv) &&
+      attestationConveyancePreference.EqualsLiteral(
+          MOZ_WEBAUTHN_ATTESTATION_CONVEYANCE_PREFERENCE_NONE)) {
+    noneAttestationRequested = true;
+  }
+
+  nsTArray<int32_t> coseAlgs;
+  // Bug 1737205 will make this infallible
+  rv = args->GetCoseAlgs(coseAlgs);
+  // If the request does not list algs, assume ES256.
+  if (NS_FAILED(rv) || coseAlgs.IsEmpty()) {
+    coseAlgs.AppendElement(
+        static_cast<int32_t>(CoseAlgorithmIdentifier::ES256));
+  }
+  // This token only supports ES256.
+  coseAlgs.RemoveElementsBy([](auto& alg) {
+    return alg != static_cast<int32_t>(CoseAlgorithmIdentifier::ES256);
+  });
+  // If there are no acceptable/supported algorithms, exit
+  if (coseAlgs.IsEmpty()) {
+    return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+  }
+
+  nsString rpId;
+  args->GetRpId(rpId);
+
+  nsTArray<uint8_t> clientDataHash;
+  rv = args->GetClientDataHash(clientDataHash);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return NS_ERROR_DOM_UNKNOWN_ERR;
+  }
+
+  CryptoBuffer rpIdHash;
+  rv = HashCString(NS_ConvertUTF16toUTF8(rpId), rpIdHash);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Optional exclusion list.
+  nsTArray<nsTArray<uint8_t>> excludeList;
+  args->GetExcludeList(excludeList);
+  for (const auto& credId : excludeList) {
+    bool isRegistered = false;
+    nsresult rv = IsRegistered(credId, rpIdHash, isRegistered);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    if (isRegistered) {
+      return NS_ERROR_DOM_INVALID_STATE_ERR;
+    }
+  }
+
+  // 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;
+  rv = GetAttestationCertificate(slot, attestPrivKey, attestCert);
+  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);
+  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, const_cast<uint8_t*>(rpIdHash.Elements()),
+      rpIdHash.Length(), privKey);
+  if (NS_WARN_IF(!keyHandleItem.get())) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Sign the challenge using the Attestation privkey (from attestCert)
+  mozilla::dom::CryptoBuffer signedDataBuf;
+  if (NS_WARN_IF(!signedDataBuf.SetCapacity(
+          1 + rpIdHash.Length() + clientDataHash.Length() + keyHandleItem->len +
+              kPublicKeyLen,
+          mozilla::fallible))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // // It's OK to ignore the return values here because we're writing into
+  // // pre-allocated space
+  (void)signedDataBuf.AppendElement(0x00, mozilla::fallible);
+  (void)signedDataBuf.AppendElements(rpIdHash, mozilla::fallible);
+  (void)signedDataBuf.AppendElements(clientDataHash, 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 (NS_WARN_IF(srv != SECSuccess)) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Signature failure: %d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  CryptoBuffer keyHandleBuf;
+  if (!keyHandleBuf.AppendSECItem(keyHandleItem.get())) {
+    return NS_ERROR_FAILURE;
+  }
+
+  CryptoBuffer attestCertBuf;
+  if (!attestCertBuf.AppendSECItem(attestCert.get()->derCert)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  CryptoBuffer signatureBuf;
+  if (!signatureBuf.AppendSECItem(signatureItem)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  CryptoBuffer pubKeyBuf;
+  if (!pubKeyBuf.AppendSECItem(pubKey->u.ec.publicValue)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  CryptoBuffer attObj;
+  rv = AssembleAttestationObject(rpIdHash, pubKeyBuf, keyHandleBuf,
+                                 attestCertBuf, signatureBuf,
+                                 noneAttestationRequested, attObj);
+  if (NS_FAILED(rv)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsTArray<uint8_t> outAttObj(std::move(attObj));
+  nsTArray<uint8_t> outKeyHandleBuf(std::move(keyHandleBuf));
+  mController->FinishRegister(
+      aTransactionId, new CtapRegisterResult(NS_OK, std::move(outAttObj),
+                                             std::move(outKeyHandleBuf)));
+  return NS_OK;
+}
+
+bool U2FSoftTokenTransport::FindRegisteredKeyHandle(
+    const nsTArray<nsTArray<uint8_t>>& aAppIds,
+    const nsTArray<nsTArray<uint8_t>>& aCredentialIds,
+    /*out*/ nsTArray<uint8_t>& aKeyHandle,
+    /*out*/ nsTArray<uint8_t>& aAppId) {
+  for (const nsTArray<uint8_t>& app_id : aAppIds) {
+    for (const nsTArray<uint8_t>& credId : aCredentialIds) {
+      bool isRegistered = false;
+      nsresult rv = IsRegistered(credId, app_id, isRegistered);
+      if (NS_SUCCEEDED(rv) && isRegistered) {
+        aKeyHandle.Clear();
+        aKeyHandle.AppendElements(credId);
+        aAppId.Assign(app_id);
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+// 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
+U2FSoftTokenTransport::GetAssertion(uint64_t aTransactionId,
+                                    uint64_t _aBrowsingContextId,
+                                    nsICtapSignArgs* args) {
+  nsresult rv;
+  if (!mInitialized) {
+    rv = Init();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  if (NS_WARN_IF(!args)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  bool requireUserVerification = false;
+  nsString userVerification;
+  // Bug 1737205 will make this infallible
+  rv = args->GetUserVerification(userVerification);
+  if (NS_SUCCEEDED(rv)) {
+    requireUserVerification = userVerification.EqualsLiteral(
+        MOZ_WEBAUTHN_USER_VERIFICATION_REQUIREMENT_REQUIRED);
+  }
+  if (requireUserVerification) {
+    return NS_ERROR_DOM_NOT_ALLOWED_ERR;
+  }
+
+  nsString rpId;
+  args->GetRpId(rpId);
+
+  nsTArray<uint8_t> clientDataHash;
+  rv = args->GetClientDataHash(clientDataHash);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return NS_ERROR_DOM_UNKNOWN_ERR;
+  }
+
+  CryptoBuffer rpIdHash;
+  rv = HashCString(NS_ConvertUTF16toUTF8(rpId), rpIdHash);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsTArray<nsTArray<uint8_t>> appIdHashes;
+  appIdHashes.AppendElement(std::move(rpIdHash));
+
+  nsTArray<uint8_t> appIdHash;
+  rv = args->GetAppIdHash(appIdHash);
+  if (NS_SUCCEEDED(rv)) {
+    appIdHashes.AppendElement(std::move(appIdHash));
+  }
+
+  nsTArray<nsTArray<uint8_t>> allowList;
+  args->GetAllowList(allowList);
+
+  nsTArray<uint8_t> chosenAppId;
+  nsTArray<uint8_t> keyHandle;
+
+  // Fail if we can't find a valid key handle.
+  if (!FindRegisteredKeyHandle(appIdHashes, allowList, keyHandle,
+                               chosenAppId)) {
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
+
+  MOZ_ASSERT(mWrappingKey);
+
+  UniquePK11SlotInfo slot(PK11_GetInternalSlot());
+  MOZ_ASSERT(slot.get());
+
+  if (NS_WARN_IF((clientDataHash.Length() != kParamLen) ||
+                 (chosenAppId.Length() != kParamLen))) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Parameter lengths are wrong! challenge=%d app=%d expected=%d",
+             (uint32_t)clientDataHash.Length(), (uint32_t)chosenAppId.Length(),
+             kParamLen));
+
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  // Decode the key handle
+  UniqueSECKEYPrivateKey privKey = PrivateKeyFromKeyHandle(
+      slot, mWrappingKey, const_cast<uint8_t*>(keyHandle.Elements()),
+      keyHandle.Length(), const_cast<uint8_t*>(chosenAppId.Elements()),
+      chosenAppId.Length());
+  if (NS_WARN_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
+  mCounter += 1;
+  ScopedAutoSECItem counterItem(4);
+  counterItem.data[0] = (mCounter >> 24) & 0xFF;
+  counterItem.data[1] = (mCounter >> 16) & 0xFF;
+  counterItem.data[2] = (mCounter >> 8) & 0xFF;
+  counterItem.data[3] = (mCounter >> 0) & 0xFF;
+  uint32_t counter = mCounter;
+  GetMainThreadSerialEventTarget()->Dispatch(NS_NewRunnableFunction(
+      "dom::U2FSoftTokenTransport::GetAssertion", [counter]() {
+        MOZ_ASSERT(NS_IsMainThread());
+        Preferences::SetUint(PREF_U2F_NSSTOKEN_COUNTER, counter);
+      }));
+
+  // Compute the signature
+  mozilla::dom::CryptoBuffer signedDataBuf;
+  if (NS_WARN_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
+  (void)signedDataBuf.AppendElements(chosenAppId.Elements(),
+                                     chosenAppId.Length(), mozilla::fallible);
+  (void)signedDataBuf.AppendElement(0x01, mozilla::fallible);
+  signedDataBuf.AppendSECItem(counterItem);
+  (void)signedDataBuf.AppendElements(
+      clientDataHash.Elements(), clientDataHash.Length(), mozilla::fallible);
+
+  if (MOZ_LOG_TEST(gNSSTokenLog, LogLevel::Debug)) {
+    nsAutoCString base64;
+    rv = Base64URLEncode(signedDataBuf.Length(), signedDataBuf.Elements(),
+                         Base64URLEncodePaddingPolicy::Omit, base64);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return NS_ERROR_FAILURE;
+    }
+
+    MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
+            ("U2F Token signing bytes (base64): %s", base64.get()));
+  }
+
+  ScopedAutoSECItem signatureItem;
+  SECStatus srv = SEC_SignData(&signatureItem, signedDataBuf.Elements(),
+                               signedDataBuf.Length(), privKey.get(),
+                               SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
+  if (NS_WARN_IF(srv != SECSuccess)) {
+    MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
+            ("Signature failure: %d", PORT_GetError()));
+    return NS_ERROR_FAILURE;
+  }
+
+  nsTArray<WebAuthnExtensionResult> extensions;
+
+  if (appIdHashes.Length() == 2) {
+    bool usedAppId = (chosenAppId == appIdHashes[1]);
+    extensions.AppendElement(WebAuthnExtensionResultAppId(usedAppId));
+  }
+
+  CryptoBuffer counterBuf;
+  if (!counterBuf.AppendSECItem(counterItem)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  CryptoBuffer signatureBuf;
+  if (!signatureBuf.AppendSECItem(signatureItem)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  CryptoBuffer chosenAppIdBuf;
+  if (!chosenAppIdBuf.Assign(chosenAppId)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  CryptoBuffer authenticatorData;
+  CryptoBuffer emptyAttestationData;
+  rv = AssembleAuthenticatorData(chosenAppIdBuf, 0x01, counterBuf,
+                                 emptyAttestationData, authenticatorData);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsTArray<uint8_t> outSignatureBuf(std::move(signatureBuf));
+  nsTArray<uint8_t> outAuthenticatorData(std::move(authenticatorData));
+  nsTArray<uint8_t> userHandle;  // unused because this is a CTAP1 token
+
+  nsTArray<RefPtr<nsICtapSignResult>> results;
+  results.AppendElement(new CtapSignResult(
+      NS_OK, std::move(keyHandle), std::move(outSignatureBuf),
+      std::move(outAuthenticatorData), std::move(userHandle),
+      std::move(chosenAppId)));
+
+  mController->FinishSign(aTransactionId, results);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+U2FSoftTokenTransport::Cancel(void) {
+  // This implementation is sync, requests can't be aborted.
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+U2FSoftTokenTransport::PinCallback(uint64_t aTransactionId,
+                                   const nsACString& aPin) {
+  // This is a U2F/CTAP1 token. It doesn't support pins.
+  return NS_ERROR_FAILURE;
+}
+
+}  // namespace mozilla::dom