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List:       ms-cryptoapi
Subject:    Re: sample code
From:       albert decker <albert_decker () PROTELINC ! COM>
Date:       1997-12-30 20:42:43
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>could anybody tell me how I can store the
>PRIVATE KEY on disk and how to use it late to decrypt the data.


Sure. (Omitting the usual overhead of acquiring contexts and so on...)

To make the diskette:
1. Create the key as an exportable key (or import it).
2. Export the key as a PRIVATEKEYBLOB, encrypting it or not as you will.
 (Encrypting using a key derived from a password is a pretty good
option, IMHO.) [Use CryptExportKey]
3. Export the key as a PUBLICKEYBLOB. [Use CryptExportKey]
4. Delete the key.
5. Write the (encrypted) PRIVATEKEYBLOB into a file (on diskette)
5. Save the PUBLICKEYBLOB "somewhere".  (So that you can distribute it
later...)

Then if someone encrypts a file/record/whatever using your public key,
you can decrypt it as follows:
1. Import the PRIVATEKEYBLOB from wherever you stored it, decrypting it
if needed.
2. Decrypt files, records, etc.
3. Delete the imported key.

Hope this helps.
>

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