Allow Apps to Voluntarily Downgrade to L3 Crypto

This merges the following changes from the Widevine CDM repository:

564f4cc  Add CdmClientPropertySet to CDM
  Adds an interface to the CDM that allows it to query its client for
  certain properties.  In this case, this includes the ability to
  specify what security level is desired, as well as support for
  service ceritifcate privacy mode.

9cfbd3e  Force Level 3 fallback
  Adds support for voluntarily invoking L3 crypto to the OEMCrypto
  wrapper.

95d12c1  Add pointer to CdmClientPropertySet class to OpenSession.
  Adds support for storing the property set on a session-by-session
  basis and choosing the appropriate crypto level.

17de442  Add Settable Properties for Clank to Android
  Adds support for setting the aforementioned properties to the
  DrmEngine

bbe704d  Fixes to force fallback to level three security
  Corrections to invoke provisioning, OEMCrypto API with configured
  security level rather than the default. Unit tests were also revised.

Note that some parts of this are also support for the ability to use
a service certificate-based privacy mode. The remaining code for
supporting this mode is still forthcoming.

Bug: 10109249
Change-Id: I2755e4dea1de3e8a56cff237360298f7b7f1bddc

libwvdrmengine/cdm/core/include/privacy_crypto.h

@@ -0,0 +1,77 @@
+// Copyright 2013 Google Inc. All Rights Reserved.
+//
+// RsaPublicKey based on //depot/google3/video/widevine/common/rsa_key.h by
+// tinskip@google.com.
+//
+// Description:
+//   Declaration of classes representing AES and RSA public keys used
+//   for signature verification and encryption.
+//
+// AES encryption details:
+//   Algorithm: AES-CBC
+//
+// RSA signature details:
+//   Algorithm: RSASSA-PSS
+//   Hash algorithm: SHA1
+//   Mask generation function: mgf1SHA1
+//   Salt length: 20 bytes
+//   Trailer field: 0xbc
+//
+// RSA encryption details:
+//   Algorithm: RSA-OAEP
+//   Mask generation function: mgf1SHA1
+//   Label (encoding paramter): empty string
+
+#ifndef CDM_BASE_PRIVACY_CRYPTO_H_
+#define CDM_BASE_PRIVACY_CRYPTO_H_
+
+#include <string>
+
+#include "openssl/aes.h"
+#include "openssl/rsa.h"
+#include "wv_cdm_types.h"
+
+namespace wvcdm {
+
+class AesCbcKey {
+ public:
+  AesCbcKey() : initialized_(false) {};
+  ~AesCbcKey() {};
+
+  bool Init(const std::string& key);
+  bool Encrypt(const std::string& in, std::string* out, std::string* iv);
+
+ private:
+  AES_KEY key_;
+  bool initialized_;
+
+  CORE_DISALLOW_COPY_AND_ASSIGN(AesCbcKey);
+};
+
+class RsaPublicKey {
+ public:
+  RsaPublicKey() : key_(NULL) {}
+  ~RsaPublicKey();
+
+  // Initializes an RsaPublicKey object using a DER encoded PKCS#1 RSAPublicKey
+  bool Init(const std::string& serialized_key);
+
+  // Encrypt a message using RSA-OAEP. Caller retains ownership of all
+  // parameters. Returns true if successful, false otherwise.
+  bool Encrypt(const std::string& clear_message,
+               std::string* encrypted_message);
+
+  // Verify RSSASSA-PSS signature. Caller retains ownership of all parameters.
+  // Returns true if validation succeeds, false otherwise.
+  bool VerifySignature(const std::string& message,
+                       const std::string& signature);
+
+ private:
+  RSA* key_;
+
+  CORE_DISALLOW_COPY_AND_ASSIGN(RsaPublicKey);
+};
+
+}  // namespace wvcdm
+
+#endif  // CDM_BASE_PRIVACY_CRYPTO_H_