About cryptology and AES

Encryption means ciphering data using a key to make the data unusable to others. Decrypting ciphered data deciphers the so called cipher text using a key to reproduce the original data. Encryption is not the same as encoding data, because encoding data solely relies on the transformation algorithm. In contrast, encryption relies on the key and the algorithm. If encoding is used to veil data, the transformation algorithm merely is the key to de-/cipher the data. This not only is very impractical because it would be required to invent a new algorithm each time a new key is required, but cannot be considered as secure, too. There is always a way to reengeneer the algorithm. Using encryption, the algorithm can be publicly available, because the level of security solely depends on the key.

AES, or Advanced Encryption Standard, is the successor of the Data Encryption Standard (DES). AES is a block code with possible key lengths of 128, 192 or 256 bit. The block length can vary between 16, 20, 24, 28 byte and 32 byte. Xbase++ currently works with a fixed block length of 16 byte. AES is considered to be thousands of times more secure than DES because the number of possible keys is higher.

For details about AES, please refer to the AES documentation published by NIST, standard code FIPS-197. See the home page of AES: http://csrc.nist.gov/encryption/aes/

The AES implementation used by Xbase++ is copyright by Dr. Brian Gladman. Original copyright follows.

Copyright note: 
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Copyright (c) 2001, Dr Brian Gladman <brg@gladman.uk.net>, Worcester, UK. 
All rights reserved. 

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Redistribution and use in source and binary forms, with or without 
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 3. The copyright holder's name must not be used to endorse or promote 
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This software is provided 'as is' with no express or implied warranties 
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Issue Date: 21/01/2002

The Secure Hash Algorithms, SHA-256, SHA-384 and SHA-512 used by Xbase++ is copyright by Mr. A.D. Gifford. Original copyright follows.

/* 
* FILE:	sha2.c 
* AUTHOR:	Aaron D. Gifford <me@aarongifford.com> 
* 
* Copyright (c) 2000-2001, Aaron D. Gifford 
* All rights reserved. 
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* SUCH DAMAGE. 
*/

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About cryptology and AES Professional