Data encryption and decryption are common operations in network-based application programs that must offer security. In order to keep pace with the high data input rate of network-based applications such as the multimedia data streaming, real-time processing of the data encryption/decryption is crucial. In this paper, we propose a new parallelization approach to improve the throughput performance for the de-facto standard data encryption and decryption algorithm, AES-CTR (Counter mode of AES). The new approach extends the size of the block encrypted at one time across the unit block boundaries, thus effectively encrypting multiple unit blocks at the same time. This reduces the associated parallelization overheads such as the number of procedure calls, the scheduling and the synchronizations compared with previous approaches. Therefore, this leads to significant throughput performance improvements on a computing platform with a general-purpose multi-core processor and a Graphic Processing Unit (GPU).