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List:       ms-cryptoapi
Subject:    Re: Salt Size?
From:       "Sergei O. Ivanov" <sergiva () MATH ! UNI-PADERBORN ! DE>
Date:       1996-11-27 23:01:54
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Jim,

the size of salt varies depending on the algorithm.
It can even vary depending on implementation. Because salt
is actually appended to key without encryption you have
to balance (as algorithm designer) when choosing a salt size:

  * if salt is too small, one can compile a dictionary with
        all possible salt values.

  * if salt is too large, it will be just a waste of space
        because it could be in principle extracted from the
        message.

Microsoft RSABase CSP uses 88-bit salt values.

Sergei
---------
Are salt values fixed- or variable-length?  The CAPI definition for the
salt parameter of keys states that it is a BYTE array (of undefined
size) and that it's length should be returned to the caller of
GetKeyParams.  SetKeyParams, however, does not allow the caller to set
the size of the salt.  I see no definitive reference for the size of
salt values in crypto literature, only examples which all differ.

Any ideas?

Thanks,
Jim Weber

--
James F. Weber                    Phone:   612-449-0187
Minnetonka Software, Inc.         Fax:     612-449-0318
James.Weber@MinnetonkaSoftware.com

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