/* (non-Javadoc)
   * @see com.amazonaws.services.s3.AmazonS3Client#initiateMultipartUpload(com.amazonaws.services.s3.model.InitiateMultipartUploadRequest)
   */
  @Override
  public InitiateMultipartUploadResult initiateMultipartUpload(
      InitiateMultipartUploadRequest initiateMultipartUploadRequest)
      throws AmazonClientException, AmazonServiceException {

    appendUserAgent(initiateMultipartUploadRequest, USER_AGENT);

    // Generate a one-time use symmetric key and initialize a cipher to encrypt object data
    SecretKey envelopeSymmetricKey = EncryptionUtils.generateOneTimeUseSymmetricKey();
    Cipher symmetricCipher =
        EncryptionUtils.createSymmetricCipher(
            envelopeSymmetricKey, Cipher.ENCRYPT_MODE, cryptoConfig.getCryptoProvider(), null);

    if (cryptoConfig.getStorageMode() == CryptoStorageMode.ObjectMetadata) {
      EncryptionMaterials encryptionMaterials =
          encryptionMaterialsProvider.getEncryptionMaterials();
      // Encrypt the envelope symmetric key
      byte[] encryptedEnvelopeSymmetricKey =
          EncryptionUtils.getEncryptedSymmetricKey(
              envelopeSymmetricKey, encryptionMaterials, cryptoConfig.getCryptoProvider());

      // Store encryption info in metadata
      ObjectMetadata metadata =
          EncryptionUtils.updateMetadataWithEncryptionInfo(
              initiateMultipartUploadRequest,
              encryptedEnvelopeSymmetricKey,
              symmetricCipher,
              encryptionMaterials.getMaterialsDescription());

      // Update the request's metadata to the updated metadata
      initiateMultipartUploadRequest.setObjectMetadata(metadata);
    }

    InitiateMultipartUploadResult result =
        super.initiateMultipartUpload(initiateMultipartUploadRequest);
    EncryptedUploadContext encryptedUploadContext =
        new EncryptedUploadContext(
            initiateMultipartUploadRequest.getBucketName(),
            initiateMultipartUploadRequest.getKey(),
            envelopeSymmetricKey);
    encryptedUploadContext.setNextInitializationVector(symmetricCipher.getIV());
    encryptedUploadContext.setFirstInitializationVector(symmetricCipher.getIV());
    currentMultipartUploadSecretKeys.put(result.getUploadId(), encryptedUploadContext);

    return result;
  }