private void actualDecryption()

in sdk1/src/main/java/com/amazonaws/services/dynamodbv2/datamodeling/encryption/DynamoDBEncryptor.java [371:414]
43 lines of code
8 McCabe index (conditional complexity)

  private void actualDecryption(
      Map<String, AttributeValue> itemAttributes,
      Map<String, Set<EncryptionFlags>> attributeFlags,
      SecretKey encryptionKey,
      Map<String, String> materialDescription)
      throws GeneralSecurityException {
    final String encryptionMode =
        encryptionKey != null
            ? encryptionKey.getAlgorithm() + materialDescription.get(symmetricEncryptionModeHeader)
            : null;
    Cipher cipher = null;
    int blockSize = -1;

    for (Map.Entry<String, AttributeValue> entry : itemAttributes.entrySet()) {
      Set<EncryptionFlags> flags = attributeFlags.get(entry.getKey());
      if (flags != null && flags.contains(EncryptionFlags.ENCRYPT)) {
        if (!flags.contains(EncryptionFlags.SIGN)) {
          throw new IllegalArgumentException(
              "All encrypted fields must be signed. Bad field: " + entry.getKey());
        }
        ByteBuffer plainText;
        ByteBuffer cipherText = entry.getValue().getB().asReadOnlyBuffer();
        cipherText.rewind();
        if (encryptionKey instanceof DelegatedKey) {
          plainText =
              ByteBuffer.wrap(
                  ((DelegatedKey) encryptionKey)
                      .decrypt(toByteArray(cipherText), null, encryptionMode));
        } else {
          if (cipher == null) {
            blockSize = getBlockSize(encryptionMode);
            cipher = Cipher.getInstance(encryptionMode);
          }
          byte[] iv = new byte[blockSize];
          cipherText.get(iv);
          cipher.init(Cipher.DECRYPT_MODE, encryptionKey, new IvParameterSpec(iv), Utils.getRng());
          plainText = ByteBuffer.allocate(cipher.getOutputSize(cipherText.remaining()));
          cipher.doFinal(cipherText, plainText);
          plainText.rewind();
        }
        entry.setValue(AttributeValueMarshaller.unmarshall(plainText));
      }
    }
  }