Reference code for ECC operations.

[ Merge of http://go/wvgerrit/113750 ]

This introduces two classes EccPublicKey and EccPrivateKey which
perform all ECC-specific crypto operations.  The main operations
required by ECC are:
- Load/serialize keys from/to X.509 DER formats
- Generate ECC signatures
- Verify ECC signatures
- Derive session keys used by other OEMCrypto operations

These new classes still need to be plugged into rest of the reference
OEMCrypto implementation.

Bug: 135283522
Test: Future CL
Change-Id: Id071cad9129f95a6eb08662322154ba7d1548d40

libwvdrmengine/oemcrypto/ref/src/scoped_object.h

@@ -0,0 +1,71 @@
+// Copyright 2021 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine License
+// Agreement.
+//
+//  Reference implementation of OEMCrypto APIs
+//
+#ifndef SCOPED_OBJECT_H_
+#define SCOPED_OBJECT_H_
+
+namespace wvoec_ref {
+
+// A generic wrapper around pointer.  This allows for automatic
+// memory clean up when the ScopedObject variable goes out of scope.
+// This is intended to be used with OpenSSL/BoringSSL structs.
+template <typename Type, void Destructor(Type*)>
+class ScopedObject {
+ public:
+  ScopedObject() : ptr_(nullptr) {}
+  ScopedObject(Type* ptr) : ptr_(ptr) {}
+  ~ScopedObject() {
+    if (ptr_) {
+      Destructor(ptr_);
+      ptr_ = nullptr;
+    }
+  }
+
+  // Copy construction and assignment are not allowed.
+  ScopedObject(const ScopedObject& other) = delete;
+  ScopedObject& operator=(const ScopedObject& other) = delete;
+
+  // Move construction and assignment are allowed.
+  ScopedObject(ScopedObject&& other) : ptr_(other.ptr_) {
+    other.ptr_ = nullptr;
+  }
+  ScopedObject& operator=(ScopedObject&& other) {
+    if (ptr_) {
+      Destructor(ptr_);
+    }
+    ptr_ = other.ptr_;
+    other.ptr_ = nullptr;
+    return *this;
+  }
+
+  explicit operator bool() const { return ptr_ != nullptr; }
+
+  Type& operator*() { return *ptr_; }
+  Type* get() const { return ptr_; }
+  Type* operator->() const { return ptr_; }
+
+  // Releasing the pointer will remove the responsibility of the
+  // ScopedObject to clean up the pointer.
+  Type* release() {
+    Type* temp = ptr_;
+    ptr_ = nullptr;
+    return temp;
+  }
+
+  void reset(Type* ptr = nullptr) {
+    if (ptr_) {
+      Destructor(ptr_);
+    }
+    ptr_ = ptr;
+  }
+
+ private:
+  Type* ptr_ = nullptr;
+};
+
+}  // namespace wvoec_ref
+
+#endif  // SCOPED_OBJECT_H_