Implement HKDF for WebCrypto (blink-side)

public/platform/WebCryptoKeyAlgorithm.h

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 45 matching lines @@
     BLINK_PLATFORM_EXPORT WebCryptoKeyAlgorithm(WebCryptoAlgorithmId, PassOwnPtr<WebCryptoKeyAlgorithmParams>);
 #endif
 
     // FIXME: Delete this in favor of the create*() functions.
     BLINK_PLATFORM_EXPORT static WebCryptoKeyAlgorithm adoptParamsAndCreate(WebCryptoAlgorithmId, WebCryptoKeyAlgorithmParams*);
 
     BLINK_PLATFORM_EXPORT static WebCryptoKeyAlgorithm createAes(WebCryptoAlgorithmId, unsigned short keyLengthBits);
     BLINK_PLATFORM_EXPORT static WebCryptoKeyAlgorithm createHmac(WebCryptoAlgorithmId hash, unsigned keyLengthBits);
     BLINK_PLATFORM_EXPORT static WebCryptoKeyAlgorithm createRsaHashed(WebCryptoAlgorithmId, unsigned modulusLengthBits, const unsigned char* publicExponent, unsigned publicExponentSize, WebCryptoAlgorithmId hash);
     BLINK_PLATFORM_EXPORT static WebCryptoKeyAlgorithm createEc(WebCryptoAlgorithmId, WebCryptoNamedCurve);
+    BLINK_PLATFORM_EXPORT static WebCryptoKeyAlgorithm createKdf(WebCryptoAlgorithmId);
 
     ~WebCryptoKeyAlgorithm() { reset(); }
 
     WebCryptoKeyAlgorithm(const WebCryptoKeyAlgorithm& other) { assign(other); }
     WebCryptoKeyAlgorithm& operator=(const WebCryptoKeyAlgorithm& other)
     {
         assign(other);
         return *this;
     }
 
     BLINK_PLATFORM_EXPORT bool isNull() const;
 
     BLINK_PLATFORM_EXPORT WebCryptoAlgorithmId id() const;
 
     BLINK_PLATFORM_EXPORT WebCryptoKeyAlgorithmParamsType paramsType() const;
 
     // Returns the type-specific parameters for this key. If the requested
     // parameters are not applicable (for instance an HMAC key does not have
     // any AES parameters) then returns 0.
     BLINK_PLATFORM_EXPORT WebCryptoAesKeyAlgorithmParams* aesParams() const;
     BLINK_PLATFORM_EXPORT WebCryptoHmacKeyAlgorithmParams* hmacParams() const;
     BLINK_PLATFORM_EXPORT WebCryptoRsaHashedKeyAlgorithmParams* rsaHashedParams() const;
     BLINK_PLATFORM_EXPORT WebCryptoEcKeyAlgorithmParams* ecParams() const;
+    BLINK_PLATFORM_EXPORT WebCryptoKdfKeyAlgorithmParams* kdfParams() const;

[eroman, 2015/01/07 00:40:31]

Why is this necessary? It looks like your other change was intended for KDF keys
to have no params (which I think makes sense).

[nharper, 2015/01/08 00:58:39]

It was added to make the switch statement in
SerializedScriptValueWriterForModules::writeCryptoKey() to be a little more
consistent, but I agree that it isn't needed (since KDF keys don't have any
params). I've removed it, as I don't think the code symmetry is worth adding
this otherwise useless class.

 
     // Write the algorithm parameters to a dictionary.
     BLINK_PLATFORM_EXPORT void writeToDictionary(WebCryptoKeyAlgorithmDictionary*) const;
 
 private:
     BLINK_PLATFORM_EXPORT void assign(const WebCryptoKeyAlgorithm& other);
     BLINK_PLATFORM_EXPORT void reset();
 
     WebPrivatePtr<WebCryptoKeyAlgorithmPrivate> m_private;
 };
 
 } // namespace blink
 
 #endif