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List:       ms-cryptoapi
Subject:    Re: Key length
From:       Miro Masnoglav <miro.masnoglav () ADACTA ! SI>
Date:       1999-11-30 13:14:01
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-----Original Message-----
From: Cristina Navarro López <crinav@LIRA.CEDETEL.TEL.UVA.ES>
To: CryptoAPI@DISCUSS.MICROSOFT.COM <CryptoAPI@DISCUSS.MICROSOFT.COM>
Date: Tuesday, November 30, 1999 1:09 PM
Subject: Key length


>Hello,
>
>I know this may sound like an stupid question, but i am a bit confused
>about the length of private and public keys generated with CryptoAPI.
>
>If there is somebody kind enough to explain me, if i use CrypGenKey which
>key length do i get? 512 bits or 1024?

Only 512 bits because you have RSA base CSP. See "The Base Provider
Private-Key Blob"
in MSDN.

>
>And why is there another kind of keys that are 40 bits or 52 bits long?

This are simmetric keys for crypt data. RSA is used for (de)crypt this
simmetric key
and for sign and verify hash. Brute force attack mean that you must try
every possible
key (2**40 or 2**52 possible keys).

>
>What does strong encryption mean? I know that it means using 128 bits but
>i do not know when, (although in Spain we cannot use strong encryption.)

2048 bit RSA and 128 bit simmetric encryption is strong.
1024 bit RSA and 64 bit simmetric encryption ??
512 bit RSA and 40 bit simmetric encryption is weak
>
>Thank you very much
>
>cris
>

Miro
--------------------------------------------------
Miro Masnoglav
e-mail: miro.masnoglav@adacta.si
URL: http:\\www.adacta.si\

ADACTA software
Dunajska 21, 1000 Ljubljana
Slovenia, Europe

tel.: +386 (061) 300 24 20
fax: +386 (061) 300 25 00
--------------------------------------------------


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