Exposing the Cast Signing Algorithm

[ Merge of http://go/wvgerrit/178076 ]

1. Exposing the Cast Signing Algorithm in cdm core.
2. Update core Cast tests to use new core CDM Cast signing API.

Bug: 279671867
Bug: 279672538
Test: com.google.android.wvts
Change-Id: Ia73c4b5e6dd61edf790bca97a321881d310e7a99
(cherry picked from commit 8996b624d73adf14db45e54653e7ddc513f3895c)

libwvdrmengine/cdm/core/src/crypto_session.cpp

@@ -1573,7 +1573,8 @@ CdmResponseType CryptoSession::GenerateDerivedKeys(
 }
 
 CdmResponseType CryptoSession::GenerateRsaSignature(const std::string& message,
-                                                    std::string* signature) {
+                                                    std::string* signature,
+                                                    RSA_Padding_Scheme scheme) {
   LOGV("Generating RSA signature: id = %u", oec_session_id_);
   RETURN_IF_NULL(signature, PARAMETER_NULL);
 
@@ -1590,7 +1591,7 @@ CdmResponseType CryptoSession::GenerateRsaSignature(const std::string& message,
               oec_session_id_, reinterpret_cast<const uint8_t*>(message.data()),
               message.size(),
               reinterpret_cast<uint8_t*>(const_cast<char*>(signature->data())),
-              &length, kSign_RSASSA_PSS),
+              &length, scheme),
           metrics_, oemcrypto_generate_rsa_signature_, sts,
           metrics::Pow2Bucket(length));
     });
@@ -3329,4 +3330,5 @@ CryptoSession* CryptoSessionFactory::MakeCryptoSession(
     metrics::CryptoMetrics* crypto_metrics) {
   return new CryptoSession(crypto_metrics);
 }
+
 }  // namespace wvcdm