Input/Output FormatFunction DescriptionPlan of ExperimentsPossible Specification ChangesLiterature and ReferencesAES Implementation Survey: Specification Hudson C. Stansbury George Mason University October 19, 2004 Introduction The purpose of this project will be to compare various existing software implementations of the Advanced Encryption Standard (AES) algorithm primarily based on performance. AES is still young next to its predecessor, the Data Encryption Standard (DES), and its security and performance qualities will determine its future as the new predominate standard block cipher algorithm. Two most important implementations currently available are the reference implementation provided at http://www.esat.kuleuven.ac.be/~rijmen/rijndael/rijndaelref.zip, and the optimized implementation, provided at http://www.esat.kuleuven.ac.be/~rijmen/rijndael/rijndael-fst-3.0.zip. System Characteristics and Additional Software Required The experiments will be performed on Windows XP over a 1.79 GHz Pentium processor, as well as a GMU-owned SunOS system, cpeo2, running on a 400 MHz Sparc processor. Each implementation might be available as compiled code, assembly, or source code in a high level language (e.g. C++, Java), the latter two requiring their own assemblers and compilers. We intend to diversify these compilers used for the experiments. Among other compilers, we plan to use the following: 1. Java 2 SDK, Standard Edition Version 1.4.1 2. ActivePerl Interpreter Version 5.8.0 3. C and C++ compilers from GCC and from Sun's Forte Developer The C and C++ compilers to be used on the Windows system have not yet been selected. It may be difficult to separately examine the effects of hardware and operating system because only two machines will be used. Input/Output Format The input will consist of plaintext files for encryptions, ciphertext files for decryptions, and keys provided as standard input. Output will consist of the ciphertext files for encryptions, plaintext files for decryptions, and performance characteristics, including the amount of data encrypted. Different implementations may have different interfaces based on whether the program interacts with a file system or standard I/O or some other interface. Function Description AES is an iterative shared-key block cipher algorithm, which allows for key sizes and block sizes of 128 bits, 192 bits, and 256 bits. The original specification of the AES algorithm can be found at http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf. Plan of Experiments We will perform experiments with several different implementations of AES and compare them based on the following qualities: 1. author 2. language 3. compiler 4. platform 5. block size (128, 192, or 256 bits) 6. key size (128, 192, or 256 bits)7. implementation structure In each experiment, one implementation of AES will be used to encrypt or decrypt as much data as possible in certain time interval. The input plaintexts will each come from a file of randomly-generated data, and the key will be selected from a list of randomly-generated keys. Schedule Monday November 8: Gain preliminary understanding of the AES algorithm and its mathematical basis. Monday November 15: Gain preliminary understanding of implementation decisions involved in AES and the range of existing implementations of AES. Monday November 15: Download, compile, and run the various implementations. Perform any necessary configurations and informally experiment with the programs in order that they will be most effectively used for formal experimentation. Wednesday November 17: Gain a closer theoretical understanding of the qualities in the implementation of AES that can affect its performance. Wednesday December 1: Devise a precise set of inputs to be used for the AES algorithm, document the justification for using those inputs, and perform the experiments. These steps will be done iteratively in order to use the results of some experiments to design the inputs of other experiments. Monday December 6: Document results and conclusions of the experiments. Describe how different implementations of AES and, generally, how different qualities of those implementations might be more or less useful in various scenarios. Monday December 13: Finalize all documentation. Possible Specification Changes The range of compilers and languages used on each system may evolve, especially since some key compilers have not yet been specified. Some of the seven currently-specified comparison criteria (see plan of experiments) may be eliminated. Also the criterion called “implementation structure” is expected to eventually describe more specific characteristics of the algorithm. Literature and References Federal Information Processing Standards Publication 197, Specification for the Advanced Encryption Standard (AES), Nov. 26, 2001, available at http://csrc.nist.gov/CryptoToolkit/aes/ Joan Daemen and Vincent Rijmen, "Rijndael: Algorithm Specification", available at http://csrc.nist.gov/encryption/aes/rijndael/ Rijndael Home Page available at http://www.esat.kuleuven.ac.be/~rijmen/rijndael/ http://ece.gmu.edu/courses/ECE636/homework/rijndael-fst-3_0.zipAES Candidates: A Survey of Implementations by Helger Lipmaa, available at http://www.tcs.hut.fi/~helger/aes/ Gaj, Kris. George Mason University. Course Lectures available at the following: http://ece.gmu.edu/courses/ECE636/homework/hw4_S04.htmhttp://ece.gmu.edu/courses/ECE636/homework/hw3_S04.htmhttp://ece.gmu.edu/courses/ECE636/viewgraphs.htm Alfred J. Menezes, Paul C. van Oorschot, and Scott A. Vanstone, Handbook of Applied Cryptography, CRC Press, Inc., Boca Raton, 1996. Kaufman, Perlman, and Speciner. Network Security: Private Communication in a Public World, 2e. Prentice Hall PTR, ISBN 0-13-046019-2,
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