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List:       ms-cryptoapi
Subject:    Re: Encryption using Public/Private Keys
From:       "Robert H. Yang" <rhyang () SPRINTMAIL ! COM>
Date:       1999-01-29 22:43:16
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Quick question - I am looking at the January '99 MSDN in the
following place :

mk:@MSITStore:H:\MSDN\crypto.chm::/devdoc/live/crypto/1using_1rxh.htm

The topic title is "Encrypting a Message".  Step 1 has this to to say :

        "Because the CryptoAPI does not permit applications to use 
         public-key algorithms to encrypt bulk data, specify a symmetric 
         algorithm such as RC2 or RC4 with the CryptGenKey call." 

The statement applies to CryptEncrypt() and CryptDecrypt(), if I am
not mistaken.  Am I misunderstanding something or is this doc just 
out-of-date ?

BTW The help for CryptEncrypt() states the following :

        "In Windows NT 5.0, the Microsoft® Enhanced RSA Provider supports
         direct encryption with RSA public keys and decryption with RSA 
         private keys."

I have yet to actually try this.  8)
-Rob

At 09:53 AM 1/25/99 -0500, you wrote:
>Hey Rob,
>
>I am using Win NT 4.0, WorkStation mode. It works perfectly fine on mine
>though to make CryptoAPI run on this machine took me more than a week.
>
>It's a little odd that with crypto API you can encrypt a message using your
>Private Key but the other side cannot decrypt it using the public key, well,
>it's good one way 'cos it tells us that using this method is dangerous.
>
>I guess on the first instance encrypting using Private Key should fail, 'cos
>anyone having your Public Key can read the message (if you send a message to
>person A, and person B also has your Public Key he could successfully read
>the message) using some other Crypto Provider if they allow decrypting the
>message using the Public Key.
>
>GSM
>
>At 03:32 PM 1/22/99 -0800, Robert H. Yang wrote:
>>What platform are you on - I was under the impression this only
>>works under NT5, ahem W2k.
>>
>>-Rob
>>Rob Yang
>>Sr. Software Engineer    http://home.sprintmail.com/~rhyang/rhysw/
>>San Jose, CA, USA
>
>Gowri Shankar Makineni
>Sr. Comms. Engineer, Ecutel
>(703)299-0807 ext. 10
>http://www.ee.duke.edu/~gsm

--
Rob Yang
Sr. Software Engineer    http://home.sprintmail.com/~rhyang/rhysw/
San Jose, CA, USA

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