Use aidl interface for Widevine service.

The interface is defined in
hardware/interfaces/drm/aidl(http://go/ag/15329852).

Test: build
  m android.hardware.drm-service.widevine -j128

Test: build_and_run_all_unit_tests.sh
  for hidl tests

Test: atest VtsAidlHalDrmTargetTest

Test:   atest vts_treble_vintf_vendor_test:vts_treble_vintf_vendor_test.DeviceManifest/SingleManifestTest#ManifestAidlHalsServed/0 -- --abi x86_64

Bug: 200055138
Bug: 170964303
Change-Id: I5654d90d8a4b0bae4b4a78e79b27c1cafec36be7

libwvdrmengine/mediadrm/aidl_src/WVGenericCryptoInterface.cpp

@@ -0,0 +1,50 @@
+//
+// Copyright 2021 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine License
+// Agreement.
+//
+
+//#define LOG_NDEBUG 0
+#define LOG_TAG "WVCdm"
+#include <log/log.h>
+
+#include "WVGenericCryptoInterface.h"
+
+#include "wv_cdm_constants.h"
+
+namespace wvdrm {
+
+using namespace std;
+using namespace wvcdm;
+
+OEMCryptoResult WVGenericCryptoInterface::signRSA(const uint8_t* wrapped_rsa_key,
+                                                  size_t wrapped_rsa_key_length,
+                                                  const uint8_t* message,
+                                                  size_t message_length,
+                                                  std::vector<uint8_t>& signature,
+                                                  RSA_Padding_Scheme padding_scheme) {
+  OEMCrypto_SESSION session;
+  OEMCryptoResult sts = OEMCrypto_OpenSession(&session);
+  if (sts != OEMCrypto_SUCCESS) return sts;
+  sts = OEMCrypto_LoadDRMPrivateKey(session, OEMCrypto_RSA_Private_Key,
+                                    wrapped_rsa_key, wrapped_rsa_key_length);
+  if (sts == OEMCrypto_SUCCESS) {
+    size_t signatureSize = 0;
+    sts = OEMCrypto_GenerateRSASignature(session, message, message_length,
+                                         NULL, &signatureSize,
+                                         padding_scheme);
+    if (sts == OEMCrypto_SUCCESS) {
+      // Should be short buffer.
+      sts = OEMCrypto_ERROR_UNKNOWN_FAILURE;
+    } else if (sts == OEMCrypto_ERROR_SHORT_BUFFER) {
+      signature.resize(signatureSize);
+      sts = OEMCrypto_GenerateRSASignature(session, message, message_length,
+                                           signature.data(), &signatureSize,
+                                           padding_scheme);
+    }
+  }
+  OEMCrypto_CloseSession(session);
+  return sts;
+}
+
+}  // namespace wvdrm