Miscelaneous updates to WebCrypto to match latest spec.

third_party/WebKit/Source/modules/crypto/SubtleCrypto.cpp

Index: third_party/WebKit/Source/modules/crypto/SubtleCrypto.cpp
diff --git a/third_party/WebKit/Source/modules/crypto/SubtleCrypto.cpp b/third_party/WebKit/Source/modules/crypto/SubtleCrypto.cpp
index 5b3f2e83ac1283188ae6045fbc76e562bfc81028..6b62ad5b60c754971e551e84a69a22324bec09b6 100644
--- a/third_party/WebKit/Source/modules/crypto/SubtleCrypto.cpp
+++ b/third_party/WebKit/Source/modules/crypto/SubtleCrypto.cpp
@@ -147,15 +147,23 @@ ScriptPromise SubtleCrypto::encrypt(ScriptState* scriptState, const AlgorithmIde
     //           the data parameter passed to the encrypt method.
     Vector<uint8_t> data = copyBytes(rawData);
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationEncrypt, algorithm, result))
+    // 14.3.1.3: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to "encrypt".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renames algorithm --> normalizedAlgorithm; no other changes in logic here.

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationEncrypt, normalizedAlgorithm, result))
         return promise;
 
-    if (!key->canBeUsedForAlgorithm(algorithm, WebCryptoKeyUsageEncrypt, result))
+    // 14.3.1.8: If the name member of normalizedAlgorithm is not equal to the
+    //           name attribute of the [[algorithm]] internal slot of key then
+    //           throw an InvalidAccessError.
+    //
+    // 14.3.1.9: If the [[usages]] internal slot of key does not contain an
+    //           entry that is "encrypt", then throw an InvalidAccessError.
+    if (!key->canBeUsedForAlgorithm(normalizedAlgorithm, WebCryptoKeyUsageEncrypt, result))
         return promise;
 
-    histogramAlgorithmAndKey(scriptState->getExecutionContext(), algorithm, key->key());
-    Platform::current()->crypto()->encrypt(algorithm, key->key(), data.data(), data.size(), result->result());
+    histogramAlgorithmAndKey(scriptState->getExecutionContext(), normalizedAlgorithm, key->key());
+    Platform::current()->crypto()->encrypt(normalizedAlgorithm, key->key(), data.data(), data.size(), result->result());
     return promise;
 }
 
@@ -173,15 +181,23 @@ ScriptPromise SubtleCrypto::decrypt(ScriptState* scriptState, const AlgorithmIde
     //           the data parameter passed to the decrypt method.
     Vector<uint8_t> data = copyBytes(rawData);
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationDecrypt, algorithm, result))
+    // 14.3.2.3: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to "decrypt".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renames algorithm --> normalizedAlgorithm; no other changes in logic here.

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationDecrypt, normalizedAlgorithm, result))
         return promise;
 
-    if (!key->canBeUsedForAlgorithm(algorithm, WebCryptoKeyUsageDecrypt, result))
+    // 14.3.2.8: If the name member of normalizedAlgorithm is not equal to the
+    //           name attribute of the [[algorithm]] internal slot of key then
+    //           throw an InvalidAccessError.
+    //
+    // 14.3.2.9: If the [[usages]] internal slot of key does not contain an
+    //           entry that is "decrypt", then throw an InvalidAccessError.
+    if (!key->canBeUsedForAlgorithm(normalizedAlgorithm, WebCryptoKeyUsageDecrypt, result))
         return promise;
 
-    histogramAlgorithmAndKey(scriptState->getExecutionContext(), algorithm, key->key());
-    Platform::current()->crypto()->decrypt(algorithm, key->key(), data.data(), data.size(), result->result());
+    histogramAlgorithmAndKey(scriptState->getExecutionContext(), normalizedAlgorithm, key->key());
+    Platform::current()->crypto()->decrypt(normalizedAlgorithm, key->key(), data.data(), data.size(), result->result());
     return promise;
 }
 
@@ -199,15 +215,23 @@ ScriptPromise SubtleCrypto::sign(ScriptState* scriptState, const AlgorithmIdenti
     //           the data parameter passed to the sign method.
     Vector<uint8_t> data = copyBytes(rawData);
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationSign, algorithm, result))
+    // 14.3.3.3: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to "sign".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renames algorithm --> normalizedAlgorithm; no other changes in logic here.

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationSign, normalizedAlgorithm, result))
         return promise;
 
-    if (!key->canBeUsedForAlgorithm(algorithm, WebCryptoKeyUsageSign, result))
+    // 14.3.3.8: If the name member of normalizedAlgorithm is not equal to the
+    //           name attribute of the [[algorithm]] internal slot of key then
+    //           throw an InvalidAccessError.
+    //
+    // 14.3.3.9: If the [[usages]] internal slot of key does not contain an
+    //           entry that is "sign", then throw an InvalidAccessError.
+    if (!key->canBeUsedForAlgorithm(normalizedAlgorithm, WebCryptoKeyUsageSign, result))
         return promise;
 
-    histogramAlgorithmAndKey(scriptState->getExecutionContext(), algorithm, key->key());
-    Platform::current()->crypto()->sign(algorithm, key->key(), data.data(), data.size(), result->result());
+    histogramAlgorithmAndKey(scriptState->getExecutionContext(), normalizedAlgorithm, key->key());
+    Platform::current()->crypto()->sign(normalizedAlgorithm, key->key(), data.data(), data.size(), result->result());
     return promise;
 }
 
@@ -225,19 +249,27 @@ ScriptPromise SubtleCrypto::verifySignature(ScriptState* scriptState, const Algo
     //           held by the signature parameter passed to the verify method.
     Vector<uint8_t> signature = copyBytes(rawSignature);
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationVerify, algorithm, result))
+    // 14.3.4.3: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to "verify".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renames algorithm --> normalizedAlgorithm; no other changes in logic here.

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationVerify, normalizedAlgorithm, result))
         return promise;
 
     // 14.3.4.5: Let data be the result of getting a copy of the bytes held by
     //           the data parameter passed to the verify method.
     Vector<uint8_t> data = copyBytes(rawData);
 
-    if (!key->canBeUsedForAlgorithm(algorithm, WebCryptoKeyUsageVerify, result))
+    // 14.3.4.9: If the name member of normalizedAlgorithm is not equal to the
+    //           name attribute of the [[algorithm]] internal slot of key then throw an
+    //           InvalidAccessError.
+    //
+    // 14.3.4.10: If the [[usages]] internal slot of key does not contain an
+    //            entry that is "verify", then throw an InvalidAccessError.
+    if (!key->canBeUsedForAlgorithm(normalizedAlgorithm, WebCryptoKeyUsageVerify, result))
         return promise;
 
-    histogramAlgorithmAndKey(scriptState->getExecutionContext(), algorithm, key->key());
-    Platform::current()->crypto()->verifySignature(algorithm, key->key(), signature.data(), signature.size(), data.data(), data.size(), result->result());
+    histogramAlgorithmAndKey(scriptState->getExecutionContext(), normalizedAlgorithm, key->key());
+    Platform::current()->crypto()->verifySignature(normalizedAlgorithm, key->key(), signature.data(), signature.size(), data.data(), data.size(), result->result());
     return promise;
 }
 
@@ -255,17 +287,21 @@ ScriptPromise SubtleCrypto::digest(ScriptState* scriptState, const AlgorithmIden
     //              by the data parameter passed to the digest method.
     Vector<uint8_t> data = copyBytes(rawData);
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationDigest, algorithm, result))
+    // 14.3.5.3: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to "digest".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renames algorithm --> normalizedAlgorithm; no other changes in logic here.

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationDigest, normalizedAlgorithm, result))
         return promise;
 
-    histogramAlgorithm(scriptState->getExecutionContext(), algorithm);
-    Platform::current()->crypto()->digest(algorithm, data.data(), data.size(), result->result());
+    histogramAlgorithm(scriptState->getExecutionContext(), normalizedAlgorithm);
+    Platform::current()->crypto()->digest(normalizedAlgorithm, data.data(), data.size(), result->result());
     return promise;
 }
 
 ScriptPromise SubtleCrypto::generateKey(ScriptState* scriptState, const AlgorithmIdentifier& rawAlgorithm, bool extractable, const Vector<String>& rawKeyUsages)
 {
+    // Method described by: https://w3c.github.io/webcrypto/Overview.html#SubtleCrypto-method-generateKey
+
     CryptoResultImpl* result = CryptoResultImpl::create(scriptState);
     ScriptPromise promise = result->promise();
 
@@ -276,12 +312,15 @@ ScriptPromise SubtleCrypto::generateKey(ScriptState* scriptState, const Algorith
     if (!CryptoKey::parseUsageMask(rawKeyUsages, keyUsages, result))
         return promise;
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationGenerateKey, algorithm, result))
+    // 14.3.5.6: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to
+    //           "generateKey".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renames algorithm --> normalizedAlgorithm; no other changes in logic here.

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationGenerateKey, normalizedAlgorithm, result))
         return promise;
 
-    histogramAlgorithm(scriptState->getExecutionContext(), algorithm);
-    Platform::current()->crypto()->generateKey(algorithm, extractable, keyUsages, result->result());
+    histogramAlgorithm(scriptState->getExecutionContext(), normalizedAlgorithm);
+    Platform::current()->crypto()->generateKey(normalizedAlgorithm, extractable, keyUsages, result->result());
     return promise;
 }
 
@@ -299,13 +338,22 @@ ScriptPromise SubtleCrypto::importKey(ScriptState* scriptState, const String& ra
     if (!CryptoKey::parseFormat(rawFormat, format, result))
         return promise;
 
+    // 14.3.9.2: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to
+    //           "importKey".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

Two changes:
  (1) renames algorithm --> normalizedAlgorithm
  (2) Moves algorithm normalization to happen before reading key data -- this is
an observable change not covered by current tests. 

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationImportKey, normalizedAlgorithm, result))
+        return promise;
+
+    // TODO(eroman): Match the procedure given in the spec to more
+    // easily provide a normative reference.
     if (rawKeyData.isDictionary()) {
         if (format != WebCryptoKeyFormatJwk) {
-            result->completeWithError(WebCryptoErrorTypeData, "Key data must be a buffer for non-JWK formats");
+            result->completeWithError(WebCryptoErrorTypeType, "Key data must be a buffer for non-JWK formats");

[eroman, 2016/07/19 18:22:49]

intentional change (crbug.com/628413). Will be clarified with comments when I
address the TODO above.

             return promise;
         }
     } else if (format == WebCryptoKeyFormatJwk) {
-        result->completeWithError(WebCryptoErrorTypeData, "Key data must be an object for JWK import");
+        result->completeWithError(WebCryptoErrorTypeType, "Key data must be an object for JWK import");
         return promise;
     }
 
@@ -313,11 +361,10 @@ ScriptPromise SubtleCrypto::importKey(ScriptState* scriptState, const String& ra
     if (!CryptoKey::parseUsageMask(rawKeyUsages, keyUsages, result))
         return promise;
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationImportKey, algorithm, result))
-        return promise;
-
     Vector<uint8_t> keyData;
+
+    // TODO(eroman): Match the procedure given in the spec to more
+    // easily provide a normative reference.
     if (rawKeyData.isArrayBuffer()) {
         keyData = copyBytes(rawKeyData.getAsArrayBuffer());
     } else if (rawKeyData.isArrayBufferView()) {
@@ -326,13 +373,15 @@ ScriptPromise SubtleCrypto::importKey(ScriptState* scriptState, const String& ra
         if (!copyJwkDictionaryToJson(rawKeyData.getAsDictionary(), keyData, result))
             return promise;
     }
-    histogramAlgorithm(scriptState->getExecutionContext(), algorithm);
-    Platform::current()->crypto()->importKey(format, keyData.data(), keyData.size(), algorithm, extractable, keyUsages, result->result());
+    histogramAlgorithm(scriptState->getExecutionContext(), normalizedAlgorithm);
+    Platform::current()->crypto()->importKey(format, keyData.data(), keyData.size(), normalizedAlgorithm, extractable, keyUsages, result->result());
     return promise;
 }
 
 ScriptPromise SubtleCrypto::exportKey(ScriptState* scriptState, const String& rawFormat, CryptoKey* key)
 {
+    // Method described by: https://w3c.github.io/webcrypto/Overview.html#dfn-SubtleCrypto-method-exportKey
+
     CryptoResultImpl* result = CryptoResultImpl::create(scriptState);
     ScriptPromise promise = result->promise();
 
@@ -343,6 +392,8 @@ ScriptPromise SubtleCrypto::exportKey(ScriptState* scriptState, const String& ra
     if (!CryptoKey::parseFormat(rawFormat, format, result))
         return promise;
 
+    // 14.3.10.6: If the [[extractable]] internal slot of key is false, then
+    //            throw an InvalidAccessError.
     if (!key->extractable()) {
         result->completeWithError(WebCryptoErrorTypeInvalidAccess, "key is not extractable");
         return promise;
@@ -355,6 +406,8 @@ ScriptPromise SubtleCrypto::exportKey(ScriptState* scriptState, const String& ra
 
 ScriptPromise SubtleCrypto::wrapKey(ScriptState* scriptState, const String& rawFormat, CryptoKey* key, CryptoKey* wrappingKey, const AlgorithmIdentifier& rawWrapAlgorithm)
 {
+    // Method described by: https://w3c.github.io/webcrypto/Overview.html#SubtleCrypto-method-wrapKey
+
     CryptoResultImpl* result = CryptoResultImpl::create(scriptState);
     ScriptPromise promise = result->promise();
 
@@ -365,21 +418,40 @@ ScriptPromise SubtleCrypto::wrapKey(ScriptState* scriptState, const String& rawF
     if (!CryptoKey::parseFormat(rawFormat, format, result))
         return promise;
 
-    WebCryptoAlgorithm wrapAlgorithm;
-    if (!parseAlgorithm(rawWrapAlgorithm, WebCryptoOperationWrapKey, wrapAlgorithm, result))
+    // 14.3.11.2: Let normalizedAlgorithm be the result of normalizing an
+    //            algorithm, with alg set to algorithm and op set to "wrapKey".
+    //
+    // 14.3.11.3: If an error occurred, let normalizedAlgorithm be the result
+    //            of normalizing an algorithm, with alg set to algorithm and op
+    //            set to "encrypt".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

rename wrapAlgorithm --> normalizedAlgorithm

+    if (!parseAlgorithm(rawWrapAlgorithm, WebCryptoOperationWrapKey, normalizedAlgorithm, result))
+        return promise;
+
+    // 14.3.11.9: If the name member of normalizedAlgorithm is not equal to the
+    //            name attribute of the [[algorithm]] internal slot of
+    //            wrappingKey then throw an InvalidAccessError.
+    //
+    // 14.3.11.10: If the name member of normalizedAlgorithm is not equal to
+    //             the name attribute of the [[algorithm]] internal slot of wrappingKey
+    //             then throw an InvalidAccessError.

[Ryan Sleevi, 2016/07/19 18:27:52]

Typo: You copied 14.3.11.9 as 14.3.11.10 - but .10 is the usages check

[eroman, 2016/07/19 19:17:13]

Good spot!

Ugh, embarrassing.

I will cross check all of these and make sure I don't have other errors.

(Looks like the URL I pasted for wrapKey() above doesn't work too so something
went wrong here)

+    if (!wrappingKey->canBeUsedForAlgorithm(normalizedAlgorithm, WebCryptoKeyUsageWrapKey, result))

[eroman, 2016/07/19 18:22:49]

This was moved to happen before extractability check (step 12). Otherwise no
logic change.

         return promise;
 
+    // TODO(crbug.com/628416): The error from step 11
+    // (NotSupportedError) is thrown after step 12 which does not match
+    // the spec order.
+
+    // 14.3.11.12: If the [[extractable]] internal slot of key is false, then
+    //             throw an InvalidAccessError.
     if (!key->extractable()) {
         result->completeWithError(WebCryptoErrorTypeInvalidAccess, "key is not extractable");
         return promise;
     }
 
-    if (!wrappingKey->canBeUsedForAlgorithm(wrapAlgorithm, WebCryptoKeyUsageWrapKey, result))
-        return promise;
-
-    histogramAlgorithmAndKey(scriptState->getExecutionContext(), wrapAlgorithm, wrappingKey->key());
+    histogramAlgorithmAndKey(scriptState->getExecutionContext(), normalizedAlgorithm, wrappingKey->key());
     histogramKey(scriptState->getExecutionContext(), key->key());
-    Platform::current()->crypto()->wrapKey(format, key->key(), wrappingKey->key(), wrapAlgorithm, result->result());
+    Platform::current()->crypto()->wrapKey(format, key->key(), wrappingKey->key(), normalizedAlgorithm, result->result());
     return promise;
 }
 
@@ -406,45 +478,75 @@ ScriptPromise SubtleCrypto::unwrapKey(ScriptState* scriptState, const String& ra
     //            method.
     Vector<uint8_t> wrappedKey = copyBytes(rawWrappedKey);
 
-    WebCryptoAlgorithm unwrapAlgorithm;
-    if (!parseAlgorithm(rawUnwrapAlgorithm, WebCryptoOperationUnwrapKey, unwrapAlgorithm, result))
-        return promise;
-
-    WebCryptoAlgorithm unwrappedKeyAlgorithm;
-    if (!parseAlgorithm(rawUnwrappedKeyAlgorithm, WebCryptoOperationImportKey, unwrappedKeyAlgorithm, result))
-        return promise;
-
-    if (!unwrappingKey->canBeUsedForAlgorithm(unwrapAlgorithm, WebCryptoKeyUsageUnwrapKey, result))
-        return promise;
-
-    histogramAlgorithmAndKey(scriptState->getExecutionContext(), unwrapAlgorithm, unwrappingKey->key());
-    histogramAlgorithm(scriptState->getExecutionContext(), unwrappedKeyAlgorithm);
-    Platform::current()->crypto()->unwrapKey(format, wrappedKey.data(), wrappedKey.size(), unwrappingKey->key(), unwrapAlgorithm, unwrappedKeyAlgorithm, extractable, keyUsages, result->result());
+    // 14.3.12.3: Let normalizedAlgorithm be the result of normalizing an
+    //            algorithm, with alg set to algorithm and op set to
+    //            "unwrapKey".
+    //
+    // 14.3.12.4: If an error occurred, let normalizedAlgorithm be the result
+    //            of normalizing an algorithm, with alg set to algorithm and op
+    //            set to "decrypt".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renamed unwrapAlgorithm --> normalizedAlgorithm

+    if (!parseAlgorithm(rawUnwrapAlgorithm, WebCryptoOperationUnwrapKey, normalizedAlgorithm, result))
+        return promise;
+
+    // 14.3.12.6: Let normalizedKeyAlgorithm be the result of normalizing an
+    //            algorithm, with alg set to unwrappedKeyAlgorithm and op set
+    //            to "importKey".
+    WebCryptoAlgorithm normalizedKeyAlgorithm;

[eroman, 2016/07/19 18:22:49]

renamed unwrappedKeyAlgorithm --> normalizedKeyAlgorithm

+    if (!parseAlgorithm(rawUnwrappedKeyAlgorithm, WebCryptoOperationImportKey, normalizedKeyAlgorithm, result))
+        return promise;
+
+    // 14.3.12.11: If the name member of normalizedAlgorithm is not equal to
+    //             the name attribute of the [[algorithm]] internal slot of
+    //             unwrappingKey then throw an InvalidAccessError.
+    //
+    // 14.3.12.12: If the [[usages]] internal slot of unwrappingKey does not
+    //             contain an entry that is "unwrapKey", then throw an
+    //             InvalidAccessError.
+    if (!unwrappingKey->canBeUsedForAlgorithm(normalizedAlgorithm, WebCryptoKeyUsageUnwrapKey, result))
+        return promise;
+
+    histogramAlgorithmAndKey(scriptState->getExecutionContext(), normalizedAlgorithm, unwrappingKey->key());
+    histogramAlgorithm(scriptState->getExecutionContext(), normalizedKeyAlgorithm);
+    Platform::current()->crypto()->unwrapKey(format, wrappedKey.data(), wrappedKey.size(), unwrappingKey->key(), normalizedAlgorithm, normalizedKeyAlgorithm, extractable, keyUsages, result->result());
     return promise;
 }
 
 ScriptPromise SubtleCrypto::deriveBits(ScriptState* scriptState, const AlgorithmIdentifier& rawAlgorithm, CryptoKey* baseKey, unsigned lengthBits)
 {
+    // Method described by: https://w3c.github.io/webcrypto/Overview.html#dfn-SubtleCrypto-method-deriveBits
+
     CryptoResultImpl* result = CryptoResultImpl::create(scriptState);
     ScriptPromise promise = result->promise();
 
     if (!canAccessWebCrypto(scriptState, result))
         return promise;
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationDeriveBits, algorithm, result))
+    // 14.3.8.2: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to
+    //           "deriveBits".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renamed algorithm --> normalizedAlgorithm; no other change in logic

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationDeriveBits, normalizedAlgorithm, result))
         return promise;
 
-    if (!baseKey->canBeUsedForAlgorithm(algorithm, WebCryptoKeyUsageDeriveBits, result))
+    // 14.3.8.7: If the name member of normalizedAlgorithm is not equal to the
+    //           name attribute of the [[algorithm]] internal slot of baseKey
+    //           then throw an InvalidAccessError.
+    //
+    // 14.3.8.8: If the [[usages]] internal slot of baseKey does not contain an
+    //           entry that is "deriveBits", then throw an InvalidAccessError.
+    if (!baseKey->canBeUsedForAlgorithm(normalizedAlgorithm, WebCryptoKeyUsageDeriveBits, result))
         return promise;
 
-    histogramAlgorithmAndKey(scriptState->getExecutionContext(), algorithm, baseKey->key());
-    Platform::current()->crypto()->deriveBits(algorithm, baseKey->key(), lengthBits, result->result());
+    histogramAlgorithmAndKey(scriptState->getExecutionContext(), normalizedAlgorithm, baseKey->key());
+    Platform::current()->crypto()->deriveBits(normalizedAlgorithm, baseKey->key(), lengthBits, result->result());
     return promise;
 }
 
 ScriptPromise SubtleCrypto::deriveKey(ScriptState* scriptState, const AlgorithmIdentifier& rawAlgorithm, CryptoKey* baseKey, const AlgorithmIdentifier& rawDerivedKeyType, bool extractable, const Vector<String>& rawKeyUsages)
 {
+    // Method described by: https://w3c.github.io/webcrypto/Overview.html#SubtleCrypto-method-deriveKey
+
     CryptoResultImpl* result = CryptoResultImpl::create(scriptState);
     ScriptPromise promise = result->promise();
 
@@ -455,24 +557,43 @@ ScriptPromise SubtleCrypto::deriveKey(ScriptState* scriptState, const AlgorithmI
     if (!CryptoKey::parseUsageMask(rawKeyUsages, keyUsages, result))
         return promise;
 
-    WebCryptoAlgorithm algorithm;
-    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationDeriveBits, algorithm, result))
-        return promise;
-
-    if (!baseKey->canBeUsedForAlgorithm(algorithm, WebCryptoKeyUsageDeriveKey, result))
+    // 14.3.7.2: Let normalizedAlgorithm be the result of normalizing an
+    //           algorithm, with alg set to algorithm and op set to
+    //           "deriveBits".
+    WebCryptoAlgorithm normalizedAlgorithm;

[eroman, 2016/07/19 18:22:49]

renamed algorithm --> normalizedAlgorithm; no other change in logic

+    if (!parseAlgorithm(rawAlgorithm, WebCryptoOperationDeriveBits, normalizedAlgorithm, result))
         return promise;
 
-    WebCryptoAlgorithm importAlgorithm;
-    if (!parseAlgorithm(rawDerivedKeyType, WebCryptoOperationImportKey, importAlgorithm, result))
+    // 14.3.7.4: Let normalizedDerivedKeyAlgorithm be the result of normalizing
+    //           an algorithm, with alg set to derivedKeyType and op set to "importKey".
+    WebCryptoAlgorithm normalizedDerivedKeyAlgorithm;

[eroman, 2016/07/19 18:22:49]

Two changes:
  (1) renamed importAlgorithm --> normalizedDerivedKeyAlgorithm
  (2) Moved normalizedDerivedKeyAlgorithm to happen before key usage check

+    if (!parseAlgorithm(rawDerivedKeyType, WebCryptoOperationImportKey, normalizedDerivedKeyAlgorithm, result))
         return promise;
 
+    // TODO(eroman): The description in the spec needs to be updated as
+    // it doesn't describe algorithm normalization for the Get Key
+    // Length parameters (https://github.com/w3c/webcrypto/issues/127)
+    // For now reference step 10 which is the closest.
+    //
+    // 14.3.7.10: If the name member of normalizedDerivedKeyAlgorithm does not
+    //            identify a registered algorithm that supports the get key length
+    //            operation, then throw a NotSupportedError.
     WebCryptoAlgorithm keyLengthAlgorithm;
     if (!parseAlgorithm(rawDerivedKeyType, WebCryptoOperationGetKeyLength, keyLengthAlgorithm, result))
         return promise;
 
-    histogramAlgorithmAndKey(scriptState->getExecutionContext(), algorithm, baseKey->key());
-    histogramAlgorithm(scriptState->getExecutionContext(), importAlgorithm);
-    Platform::current()->crypto()->deriveKey(algorithm, baseKey->key(), importAlgorithm, keyLengthAlgorithm, extractable, keyUsages, result->result());
+    // 14.3.7.11: If the name member of normalizedAlgorithm is not equal to the
+    //            name attribute of the [[algorithm]] internal slot of baseKey
+    //            then throw an InvalidAccessError.
+    //
+    // 14.3.7.12: If the [[usages]] internal slot of baseKey does not contain
+    //            an entry that is "deriveKey", then throw an InvalidAccessError.
+    if (!baseKey->canBeUsedForAlgorithm(normalizedAlgorithm, WebCryptoKeyUsageDeriveKey, result))
+        return promise;
+
+    histogramAlgorithmAndKey(scriptState->getExecutionContext(), normalizedAlgorithm, baseKey->key());
+    histogramAlgorithm(scriptState->getExecutionContext(), normalizedDerivedKeyAlgorithm);
+    Platform::current()->crypto()->deriveKey(normalizedAlgorithm, baseKey->key(), normalizedDerivedKeyAlgorithm, keyLengthAlgorithm, extractable, keyUsages, result->result());
     return promise;
 }