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List:       ms-cryptoapi
Subject:    Re: One more complain about CryptoAPI (from the CSP developer
From:       GP Jayan <jayan () NEST ! STPT ! SOFT ! NET>
Date:       1998-01-27 1:59:10
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To be clear, the "encryptedkey" in SIMPLEBLOB is a PKCS #1 (blochType=2) value. I \
believe, RSALab defined PKCS #1 in a way to use with many kind of algorithms \
including the variable key length one. I have implemented RC5 key export well by just \
following PKCS #1 standard.


I hope this will help you,

GP Jayan

-----Original Message-----
From: Bronislav Kavsan <bkavsan@IRE-MA.COM>
To: CryptoAPI@DISCUSS.MICROSOFT.COM <CryptoAPI@DISCUSS.MICROSOFT.COM>
Date: Tuesday, January 27, 1998 5:43 AM
Subject: One more complain about CryptoAPI (from the CSP developer perspective)


> This is one of my major complains about CryptoAPI.
> 
> CryptoAPI SIMPLEBLOB header doesn't include the key length of the key inside the
> blob. And this is fine for the fixed length algorithms (e.g.DES).
> 
> But for the variable key length algorithms (e.g. RC5) - it is a major pain in
> the (blip) for developing code and crypto-hardware to deal with it.
> 
> How can I figure out the length of the key inside the SIMPLEBLOB?
> 
> Microsoft recommends the following algorithm:
> 
> 1) decrypt SIMPLEBLOB with you Private Key (EXPOSING THE SECRET KEY INSIDE THE
> BLOB!!!)
> 2) search decrypted blob backwards till you find 0 (keys are terminated by 0 and
> then padded with non-zero random bytes)
> 3) calculate the length of the key
> 
> I think it was an oversight in the SIMPLEBLOB structure and must be corrected.
> 
> --
> Bronislav Kavsan
> IRE Secure Solutions, Inc.
> 100 Conifer Hill Drive  Suite 513
> Danvers, MA  01923
> voice: 978-739-2384
> http://www.ire.com
> 

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