to decryption of hash value (hash(PASSWORD, 'md5'))

[hitg...@gmail.com]

please help me SYBASE ASE VERSION 15.0.2

QUERY :
SELECT hash(PASSWORD, 'md5') FROM EMP

RESULT:
77d25860a61f0dfd785507d9fc48fe23

QUESTION !
1. how can i convert these hash value into original password
value in ASE15.0.2

2. IS there any faility to decrypr the hash function value in
ASE15.0.2

[michael...@gmail.com]

On Jan 8, 7:40 am, hitgon...@gmail.com wrote:
> please help me SYBASE ASE VERSION 15.0.2
>
> QUERY :
> SELECT hash(PASSWORD, 'md5') FROM EMP
>
> RESULT:
> 77d25860a61f0dfd785507d9fc48fe23
>
> QUESTION !
> 1. how can i convert these hash value into original password
> value in ASE15.0.2

You can't - an MD5 hash is a one way hash.

>
> 2. IS there any faility to decrypr the hash function value in
> ASE15.0.2

No - because this is fundamentally impossible to do from a hash.

Michael

[Rob Verschoor]

It is true that 'hashing' and 'encryption' are often used incorrectly so
that can be a source of confusion. However, there's a fundamental difference
between 'hashing' and 'encryption'.
While both involve are cryptographic techniques, hashing is a one-way
function while encryption is symmetrical. This means that for hashing you
cannot derive the original cleartext value back from the hashed text, while
for encryption you can (using the encryption key/keys).
An underlying aspect is that hash algorithms tend to generate a fixed-length
hash value irrespective of the size of the source data being hashed.
As a result, for hashing, information is lost in the process of scrambling
the cleartext, so it is impossible to restore that. A different way to put
it is that for hashing, the hashed data is smaller than the source data,
whereas for encryption, the encrypted data will always be larger than the
the source text (this is indeed what you can observe for columns encrypted
with ASE's column encryption).
An example application of hashing is a password check whereby the password
is hashed and the hashed data is stored. When someone enters the password,
this is first hashed, and the hash text is compared with the stored hash
text. When these are identical, the passwords are considerd to be identical.
There is a wide body of knowledge around the mathematical properties of
various hashing and encryption algorithms. The MD5 and SHA algorithms
supported by ASE are industry standards. See elsewhere for details on these
algorithms.

HTH,

Rob V.
-------------------------------------------------------------
Rob Verschoor

Certified Sybase Professional DBA for ASE 12.5/12.0/11.5/11.0
and Replication Server 12.5 / TeamSybase

Author of Sybase books (order online at www.sypron.nl/shop):
"Tips, Tricks & Recipes for Sybase ASE" (ASE 15 edition)
"The Complete Sybase ASE Quick Reference Guide"
"The Complete Sybase Replication Server Quick Reference Guide"

mailto:r...@YOUR.SPAM.sypron.nl.NOT.FOR.ME
http://www.sypron.nl
Sypron B.V., P.O.Box 10695, 2501HR Den Haag, The Netherlands
-------------------------------------------------------------

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