code: private AlgorithmParameterSpec getAlgorithmParameterSpec(byte[] ivBuffer) {
  		int length = ivLength == 0  && ivBuffer != null ? ivBuffer.length : ivLength;
  		String[] parts = algorithm.split("/");
  		if(parts.length > 1 && parts[1].equalsIgnoreCase("GCM")) {
  			return new GCMParameterSpec(tLen > 0 ? tLen: 128, ivBuffer, 0, length);
  		}
  		return new IvParameterSpec(ivBuffer, 0, length);
  	}
docs: <p>Returns the algorithm parameter specification.</p>
  @param ivBuffer
  @return