Cryptography and Encryption

[rodrigo@xxxxxxxxxxxxxxxx (Rodrigo de Almeida Sodré)]

MD5 is not an encryption algorithm, but a hash (also called one way =
hash
function or digest algorithm) so it should be used only for processing =
the
hash of data, and not for encryption/decryption. This is exactly the
advantage on using a a hash algorithm with passwords.

Although its not recommended for security reasons, it is possible to =
use a
hash algorithm to hide and retrieve hidden information (encrypt/decrypt =
in
other words) with this meta-algorithm:

1. create and initialize (with a seed) a hash object;
2. calculate the hash; (the hash is usualy a byte array)
3. make a XOR operation with the hash block and one data block with, at
maximum, the same size of the hash size;
4. if there is more information, goto 2

Regards

Rodrigo A. Sodr=E9
Analista de Sistemas
F=F3ton Inform=E1tica e Servi=E7os
(061) 328-5060 R:243
rodrigo@xxxxxxxxxxxxxxxx

> -----Original Message-----
> From: Biju Nambisan [mailto:biju.nambisan@xxxxxxxxx]
> Sent: Tuesday, February 29, 2000 8:15 AM
> To: servlet-interest@xxxxxxxxxxxx; java@xxxxxxxx;
> advanced-java@xxxxxxxxxxxxxxxx
> Subject: Cryptography and Encryption
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>=20
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> Hi! All,
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> I am trying to encode the password using the MD5 algorithm thats
> provided with the jdk1.2.We also have a necessity to decrypt the
> password....Can somebody who has worked on this suggest the code that
> goes in for decrypting.(We are interested in using MD5 for=20
> decrypting as
> well)
> Are there any freeware packages that can be imported and used ??
> This is with reference to servlets...
> Please respond ASAP...
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> Thanks in Advance!!
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> Regards,
> Biju
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> ---
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