////////////////////////////////////////////////////////////////////////////////
// Copyright 2018 Google LLC.
//
// This software is licensed under the terms defined in the Widevine Master
// License Agreement. For a copy of this agreement, please contact
// widevine-licensing@google.com.
////////////////////////////////////////////////////////////////////////////////

#include "common/signature_util.h"

#include <memory>
#include <string>

#include "util/status.h"
#include "common/aes_cbc_util.h"
#include "common/rsa_key.h"
#include "common/sha_util.h"

namespace widevine {
namespace signature_util {

util::Status GenerateAesSignature(const std::string& message, const std::string& aes_key,
                                  const std::string& aes_iv, std::string* signature) {
  if (signature == nullptr) {
    return util::Status(util::error::INVALID_ARGUMENT, "signature is nullptr");
  }
  std::string hash = Sha1_Hash(message);
  if (hash.empty()) {
    return util::Status(util::error::INTERNAL, "Computed hash is empty");
  }
  std::string sig = crypto_util::EncryptAesCbc(aes_key, aes_iv, hash);
  if (sig.empty()) {
    return util::Status(util::error::INTERNAL,
                        "Computed AES signature is empty");
  }
  *signature = sig;
  return util::OkStatus();
}

util::Status GenerateRsaSignature(const std::string& message,
                                  const std::string& private_key,
                                  std::string* signature) {
  if (signature == nullptr) {
    return util::Status(util::error::INVALID_ARGUMENT, "signature is nullptr");
  }
  std::unique_ptr<RsaPrivateKey> rsa_private_key(
      RsaPrivateKey::Create(private_key));
  if (rsa_private_key == nullptr) {
    return util::Status(util::error::INTERNAL,
                        "Failed to construct a RsaPrivateKey");
  }
  std::string sig;
  if (!rsa_private_key->GenerateSignature(message, &sig)) {
    return util::Status(util::error::INTERNAL,
                        "Failed to generate a RSA signature");
  }
  if (sig.empty()) {
    return util::Status(util::error::INTERNAL,
                        "Computed RSA signature is empty");
  }
  *signature = sig;
  return util::OkStatus();
}

}  // namespace signature_util
}  // namespace widevine