基于G.729A和AES的分组语音保密通信

AES分组密码由多轮迭代的轮函数构成，对轮函数包括的4个面向字节的变换：字节变换、行移位、列混合和加载子密钥作简要介绍和分析；并简要描述了G．729A的编码、解码器的工作流程和参数结构．由于AES标准仅支持128bit的分组加密，而G．729A语音编码帧的大小为80bit，所以不能直接应用AES来加密G．729A的编码语音来实现语音保密通信，在不损害AES的安全强度下，提出两个适用于加密G．729A编码语音帧的AES修正方案：AES160和AES80，根据分组密码的随机性测试、明密独立性测试、雪崩效应测试分析AES160和AES80密码统计性能，测试结果表明AES160和AES80都有优秀的密码学统计性能，最后利用随机误码，分析基于G．729A和AES的语音保密通信系统的抗误码性能，结果表明AES160和AES80适用于加密G．729A的语音编码帧，并保留了AES的密码安全性能。

Packet Speech Secure Communications Base on G. 729A and AES

The AES block cipher is composed of iterative round functions. The four different byte-oriented transformations, including SubBytes, ShiftRows, MixColumns and AddRoundKey, in the round function of AES are introduced and analyzed briefly in this paper. Also, the coder parameters and principle of the encoder and decoder of G.729A speech codec are described simply. Because AES only supports 128 bits data blocks size, and there are 80 bits in a G.729A encoded frame, it is impossible to encrypt a G.729A encoded frame by applying AES block cipher directly. In this paper, two revisions of AES, AES160 and AES80, are proposed to encrypt the G.729A encoded frames. The two new block ciphers have the same security as the original AES. Then the statistical performance tests of block cipher algorithm designing, including random test, plaintext-ciphertext independence test and dependence test, are applied to analyze the security of AES160 and AES80. The statistical performance tests show that both of the two block ciphers have excellent statistical performances. Finally, the random bits errors are inserted into the encrypted data to analyze the bit error robustness capability of the packet speech secure communication. The results indicate that the two algorithms, AES160 and AES80, are suitable for encrypting the G.729A encoded frame and have the same security as AES.