可重构的串行高级加密标准加解密电路设计

为了进一步提高高级加密标准(AES)算法在现场可编程门阵列(FPGA)上的硬件资源使用效率,提出一种可支持密钥长度128/192/256位串行AES加解密电路的实现方案。该设计采用复合域变换实现字节乘法求逆,同时实现列混合与逆列混合的资源共享以及三种AES算法密钥扩展共享。该电路在Xilinx Virtex-Ⅴ系列的FPGA上实现,硬件资源消耗为1871 slice、4 RAM。结果表明,在最高工作频率173.904 MHz时,密钥长度128/192/256位AES加解密吞吐率分别可达2119/1780/1534 Mb.s-1。该设计吞吐率/硬件资源比值较高,且适用支持千兆以太网

New Cryptographic Algorithms for Enhancing Security of Voice Data

A real-time application Voice over Internet Protocol (VoIP) is the technology that enables voice packets transmission over internet protocol (IP). Security is of concern whenever open networks are to be used. In general, the real-time applications suffer from packet latency and loss due to the nature of IP network. Cryptographic systems may be used to achieve VoIP security, but their impact on the Quality of Services (QoS) should be minimized. Most of the known encryption algorithms are computationally expensive resulting in a significant amount of time added to packet delay. VoIP is usually used by public users resulting in a key exchange problem and a trusted intermediate authority normally takes this responsibility. In this research, VoIP security was enhanced via a proposed cryptographic system. The proposed solution consists of a simple, but strong encryption/decryption algorithm as well as an embedded method to exchange the keys between the users. In this research, a new keys is generated in a random fashion and then used to encrypt each new voice packet to strengthen the security level. Key exchange is carried out by inserting the key with the ciphered voice packet that depends on the table of the key positions at the sender and receiver sides, and the target receiver is the only one who is able to extract the key. The encryption process in this research is divided into three main stages: key generation, encryption process, and key insertion process. The decryption process on the other hand is divided into two main stages: key extraction process, and decryption process. The proposed solution was implemented and tested and the results showed that the required time for the security processes is minimized compared to some known algorithms such as AES_Rijndael algorithm. Furthermore, the analysis has proved that the security level has a direct relationship to the key length and the voice packet size in that large packet size requires more processing time. Finally, the implementation result in this research shows the average time needed to encrypt and decrypt a voice packet size using a proposed algorithm with the long key of 1024-bits is much smaller than AES_Rijndael algorithm with a short key length of 128-bits