Bug 1034855 - Implement SPKI import/export for ECDH r=keeler,rbarnes

dom/crypto/CryptoKey.cpp

@@ -322,6 +322,23 @@ CryptoKey::PublicKeyFromSpki(CryptoBuffer& aKeyData,
     return nullptr;
   }
 
+  // Check for id-ecDH. Per the WebCrypto spec we must support it but NSS
+  // does unfortunately not know about it. Let's change the algorithm to
+  // id-ecPublicKey to make NSS happy.
+  if (SECITEM_ItemsAreEqual(&SEC_OID_DATA_EC_DH, &spki->algorithm.algorithm)) {
+    // Retrieve OID data for id-ecPublicKey (1.2.840.10045.2.1).
+    SECOidData* oidData = SECOID_FindOIDByTag(SEC_OID_ANSIX962_EC_PUBLIC_KEY);
+    if (!oidData) {
+      return nullptr;
+    }
+
+    SECStatus rv = SECITEM_CopyItem(spki->arena, &spki->algorithm.algorithm,
+                                    &oidData->oid);
+    if (rv != SECSuccess) {
+      return nullptr;
+    }
+  }
+
   return SECKEY_ExtractPublicKey(spki.get());
 }
 
@@ -343,11 +360,25 @@ CryptoKey::PublicKeyToSpki(SECKEYPublicKey* aPubKey,
                      CryptoBuffer& aRetVal,
                      const nsNSSShutDownPreventionLock& /*proofOfLock*/)
 {
-  ScopedSECItem spkiItem(PK11_DEREncodePublicKey(aPubKey));
-  if (!spkiItem.get()) {
-    return NS_ERROR_DOM_INVALID_ACCESS_ERR;
+  ScopedCERTSubjectPublicKeyInfo spki(SECKEY_CreateSubjectPublicKeyInfo(aPubKey));
+  if (!spki) {
+    return NS_ERROR_DOM_OPERATION_ERR;
   }
 
+  // Per WebCrypto spec we must export ECDH SPKIs with the algorithm OID
+  // id-ecDH (1.3.132.112). NSS doesn't know about that OID and there is
+  // no way to specify the algorithm to use when exporting a public key.
+  if (aPubKey->keyType == ecKey) {
+    SECStatus rv = SECITEM_CopyItem(spki->arena, &spki->algorithm.algorithm,
+                                    &SEC_OID_DATA_EC_DH);
+    if (rv != SECSuccess) {
+      return NS_ERROR_DOM_OPERATION_ERR;
+    }
+  }
+
+  const SEC_ASN1Template* tpl = SEC_ASN1_GET(CERT_SubjectPublicKeyInfoTemplate);
+  ScopedSECItem spkiItem(SEC_ASN1EncodeItem(nullptr, nullptr, spki, tpl));
+
   aRetVal.Assign(spkiItem.get());
   return NS_OK;
 }

dom/crypto/WebCryptoCommon.h

@@ -92,6 +92,11 @@
 // Define an unknown mechanism type
 #define UNKNOWN_CK_MECHANISM        CKM_VENDOR_DEFINED+1
 
+// python security/pkix/tools/DottedOIDToCode.py id-ecDH 1.3.132.112
+static const uint8_t id_ecDH[] = { 0x2b, 0x81, 0x04, 0x70 };
+const SECItem SEC_OID_DATA_EC_DH = { siBuffer, (unsigned char*)id_ecDH,
+                                     PR_ARRAY_SIZE(id_ecDH) };
+
 namespace mozilla {
 namespace dom {
 

dom/crypto/WebCryptoTask.cpp

@@ -258,6 +258,26 @@ GetKeySizeForAlgorithm(JSContext* aCx, const ObjectOrString& aAlgorithm,
   return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
 }
 
+inline bool
+MapOIDTagToNamedCurve(SECOidTag aOIDTag, nsString& aResult)
+{
+  switch (aOIDTag) {
+    case SEC_OID_SECG_EC_SECP256R1:
+      aResult.AssignLiteral(WEBCRYPTO_NAMED_CURVE_P256);
+      break;
+    case SEC_OID_SECG_EC_SECP384R1:
+      aResult.AssignLiteral(WEBCRYPTO_NAMED_CURVE_P384);
+      break;
+    case SEC_OID_SECG_EC_SECP521R1:
+      aResult.AssignLiteral(WEBCRYPTO_NAMED_CURVE_P521);
+      break;
+    default:
+      return false;
+  }
+
+  return true;
+}
+
 // Helper function to clone data from an ArrayBuffer or ArrayBufferView object
 inline bool
 CloneData(JSContext* aCx, CryptoBuffer& aDst, JS::Handle<JSObject*> aSrc)
@@ -1682,16 +1702,12 @@ private:
 
   virtual nsresult DoCrypto() MOZ_OVERRIDE
   {
-    if (!mFormat.EqualsLiteral(WEBCRYPTO_KEY_FORMAT_JWK)) {
-      return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
-    }
-
     // Import the key data itself
     ScopedSECKEYPublicKey pubKey;
     ScopedSECKEYPrivateKey privKey;
 
     nsNSSShutDownPreventionLock locker;
-    if (mJwk.mD.WasPassed()) {
+    if (mFormat.EqualsLiteral(WEBCRYPTO_KEY_FORMAT_JWK) && mJwk.mD.WasPassed()) {
       // Private key import
       privKey = CryptoKey::PrivateKeyFromJwk(mJwk, locker);
       if (!privKey) {
@@ -1700,20 +1716,48 @@ private:
 
       mKey->SetPrivateKey(privKey.get());
       mKey->SetType(CryptoKey::PRIVATE);
-    } else {
+    } else if (mFormat.EqualsLiteral(WEBCRYPTO_KEY_FORMAT_SPKI) ||
+               (mFormat.EqualsLiteral(WEBCRYPTO_KEY_FORMAT_JWK) &&
+                !mJwk.mD.WasPassed())) {
       // Public key import
+      if (mFormat.EqualsLiteral(WEBCRYPTO_KEY_FORMAT_SPKI)) {
+        pubKey = CryptoKey::PublicKeyFromSpki(mKeyData, locker);
+      } else {
         pubKey = CryptoKey::PublicKeyFromJwk(mJwk, locker);
+      }
+
       if (!pubKey) {
         return NS_ERROR_DOM_DATA_ERR;
       }
 
-      mKey->SetPublicKey(pubKey.get());
-      mKey->SetType(CryptoKey::PUBLIC);
+      if (mFormat.EqualsLiteral(WEBCRYPTO_KEY_FORMAT_SPKI)) {
+        if (!CheckEncodedECParameters(&pubKey->u.ec.DEREncodedParams)) {
+          return NS_ERROR_DOM_OPERATION_ERR;
         }
 
+        // Construct the OID tag.
+        SECItem oid = { siBuffer, nullptr, 0 };
+        oid.len = pubKey->u.ec.DEREncodedParams.data[1];
+        oid.data = pubKey->u.ec.DEREncodedParams.data + 2;
+
+        // Find a matching and supported named curve.
+        if (!MapOIDTagToNamedCurve(SECOID_FindOIDTag(&oid), mNamedCurve)) {
+          return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+        }
+      }
+
+      mKey->SetPublicKey(pubKey.get());
+      mKey->SetType(CryptoKey::PUBLIC);
+    } else {
+      return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+    }
+
+    // Extract 'crv' parameter from JWKs.
+    if (mFormat.EqualsLiteral(WEBCRYPTO_KEY_FORMAT_JWK)) {
       if (!NormalizeNamedCurveValue(mJwk.mCrv.Value(), mNamedCurve)) {
         return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
       }
+    }
 
     return NS_OK;
   }

dom/crypto/test/test-vectors.js

@@ -472,6 +472,20 @@ tv = {
       y: "is9pWAaneK4RdxmdLfsq5IwizDmUS2w8OGS99sKm3ek"
     },
 
+    // vector with algorithm = id-ecDH
+    spki: util.hex2abv(
+      "3056301006042b81047006082a8648ce3d030107034200045ce7b86e3b326604" +
+      "03e63712ef0998deae1027faec3c1be9f76f934dfeb58e98f4cf075b39405dd1" +
+      "f1adeb090107edcfb2b4963739d87679e3056cb0557d0adf"
+    ),
+
+    // vector with algorithm = id-ecPublicKey
+    spki_id_ecpk: util.hex2abv(
+      "3059301306072a8648ce3d020106082a8648ce3d030107034200045ce7b86e3b" +
+      "32660403e63712ef0998deae1027faec3c1be9f76f934dfeb58e98f4cf075b39" +
+      "405dd1f1adeb090107edcfb2b4963739d87679e3056cb0557d0adf"
+    ),
+
     secret: util.hex2abv(
       "35669cd5c244ba6c1ea89b8802c3d1db815cd769979072e6556eb98548c65f7d"
     )

dom/crypto/test/tests.js

@@ -2191,3 +2191,65 @@ TestArray.addTest(
       .then(complete(that), error(that));
   }
 );
+
+// -----------------------------------------------------------------------------
+TestArray.addTest(
+  "SPKI import/export of public ECDH keys (P-256)",
+  function () {
+    var that = this;
+    var alg = { name: "ECDH" };
+    var keys = ["spki", "spki_id_ecpk"];
+
+    function doImport(key) {
+      return crypto.subtle.importKey("spki", tv.ecdh_p256[key], alg, true, ["deriveBits"]);
+    }
+
+    function doExport(x) {
+      return crypto.subtle.exportKey("spki", x);
+    }
+
+    function nextKey() {
+      var key = keys.shift();
+      var imported = doImport(key);
+      var derived = imported.then(doExport);
+
+      return derived.then(function (x) {
+        if (!util.memcmp(x, tv.ecdh_p256.spki)) {
+          throw "exported key is invalid";
+        }
+
+        if (keys.length) {
+          return nextKey();
+        }
+      });
+    }
+
+    nextKey().then(complete(that), error(that));
+  }
+);
+
+// -----------------------------------------------------------------------------
+TestArray.addTest(
+  "SPKI/JWK import ECDH keys (P-256) and derive a known secret",
+  function () {
+    var that = this;
+    var alg = { name: "ECDH" };
+
+    var pubKey, privKey;
+    function setPub(x) { pubKey = x; }
+    function setPriv(x) { privKey = x; }
+
+    function doDerive() {
+      var alg = { name: "ECDH", public: pubKey };
+      return crypto.subtle.deriveBits(alg, privKey, tv.ecdh_p256.secret.byteLength * 8);
+    }
+
+    Promise.all([
+      crypto.subtle.importKey("spki", tv.ecdh_p256.spki, alg, false, ["deriveBits"])
+        .then(setPub),
+      crypto.subtle.importKey("jwk", tv.ecdh_p256.jwk_priv, alg, false, ["deriveBits"])
+        .then(setPriv)
+    ]).then(doDerive)
+      .then(memcmp_complete(that, tv.ecdh_p256.secret), error(that));
+  }
+);