完成集中式对称密钥的分配工作

说明：作为通讯的双方A和B，都已经分别和KDC拥有会话密钥Ka和Kb，但A、B之间事先没有保密通道，需要依赖KDC为它们的会话分配临时密钥Ks。在完成会话密钥Ks的分配后，A利用Ks对特定文件（test-1.txt）进行加密，并发送给B；B利用Ks对密文进行解密，并对比解密后的明文信息同原来的文件是否一致。

要求：

（1）JAVA语言编程实现，基于DES完成对称密码技术的加/解密（JAVA有库函数支持）；

（2）通信内容为一文本文件（test-1.txt）；

（3）基于网络完成密钥分配工作（作为通信的双方A、B应部署于两台主机上，KDC可以部署在其中一台主机上或第三台主机上）；

（4）所分配的对称密钥皆为一次一密，随机产生；

（5）具体密钥分配过程请以课本中基于KDC的集中式密钥分配方案为参考，完成从步骤1到步骤5的全过程；-Complete centralized symmetric key distribution job descr iption: As both A and B Communications, have been separately owned and KDC session key Ka and Kb, but no prior confidential channel between A, B, they need to rely KDC for a session assigned temporary key Ks. After the completion of the distribution of the session key Ks, A specific file using Ks (test-1.txt) encrypts and sends B　B using Ks to decrypt the ciphertext, and the decrypted plaintext comparison with the original whether the files are consistent. Requirements: (1) JAVA programming language, based on DES symmetric cryptographic techniques to complete the encryption/decryption (JAVA there are library functions support)　(2) the contents of a text file to communicate (test-1.txt)　(3) based on the network completion of key distribution work (both as a communications A, B should be deployed on two hosts, KDC can be deployed on a single host or hosts on which third)　symmetric key (4) are all assigned a a secret, randomly g