本文为美国托莱多大学（作者：Bhavana Daddala）的硕士论文，共75页。

安全是发展中国家最关心的问题之一。重要的是要确保通信各方之间的信息安全传输，保护他们免受攻击。已经有许多标准和开发的加密协议作为资源提供，并根据需求使用。在本论文中，我们提出一个自定义的加密算法和一个安全传输资讯的认证方案。该算法是高级加密标准（AES）的一个变种，可以在多个设备之间执行。AES只使用一个私钥（对称密钥）来加密数据。实现工作在一个标准的8次不可约多项式上，该多项式进一步用于计算算法中每一层工作所需的乘逆表、S盒和逆S盒。与AES相比，我们在实现中使用了16个8次不可约多项式，而不是一个。AES的密钥大小通常为128、192和256位；我们使用128位密钥。与对称加密不同，非对称加密使用两个密钥：私钥和公钥。公钥在通信双方之间共享，私钥则保密。密钥应该具有足够的长度，以保持加密强度。因此，对于非对称加密，它们通常从512位到2048位或更多。通信双方可以从公共私钥开始，并商定一个公共密钥（会话密钥），该密钥可以用作AES的密钥。Diffie-Hellman密钥交换协议使用AES和RSA算法的组合，从而产生可靠的密码系统。该算法利用组合框架设计了一种新的密钥建立和协商协议。介绍了两台设备之间通信协议的实现，并展望了使用集中式服务器处理多台设备的前景。本文最终建立了一种不同的加密方法，通过提供对中间人攻击的保护来增强安全性。自定义的算法是用Python实现的。

Security is one of the biggest concerns inthe developing world. It is important to ensure a safe transfer of informationbetween communicating parties, protecting them from attacks. Many standards anddeveloped encryption protocols are available as resources and are used based onthe requirements. In this thesis, we propose a customized encryption algorithmand an authentication scheme to safely transfer information. The algorithm is avariation of Advanced Encryption Standard (AES) and is carried out betweenmultiple devices. AES uses only one private key (symmetric key) to encrypt thedata. The implementation works on a single standard irreducible polynomial ofdegree ‘8’ which is further used to compute multiplicative inverse tables,S-boxes and inverse S-Boxes required for the working of every layer in thealgorithm. As compared to AES, we use sixteen irreducible polynomials of degree‘8’ instead of one in our implementation. Key sizes for AES are usually 128,192 and 256 bits in size; we use a 128-bit key. Unlike symmetric encryption,asymmetric encryption uses two keys, private and public keys. The public keysare shared among the communicating parties, while the private keys are keptsecret. The keys are supposed to be large in size to maintain strength. Thus,they usually range from 512 bits to 2048 bits or more for asymmetriccryptography. The communicating parties can start with public-private keys andagree upon a common key (session key) which can be used as a key to AES.Diffie-Hellman key exchange protocol uses a combination of AES and RSAalgorithms resulting in reliable cryptosystems. Our algorithm focuses ondevising a new protocol for key establishment and agreement, using thecombination framework. The implementation of the communication protocol betweentwo devices, with a prospect of working with multiple devices using a centralizedserver, is presented. The outcome is to establish a different approach towardsencryption and enhance security by providing protection againstMan-in-the-Middle attacks. The customized algorithms are implemented usingPython.

1 引言

2 文献回顾

3 标准加密方法

4 自定义加密方法

5 性能与实现

6 结论与未来工作展望

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