Aloha, The public key is derived from the private key. Anyone in possession of the private key is by definition also in possession of the public key. The same is not true in reverse, a party can possess the public key without the ability to (reasonably) discover the matching private key. The public key is normally used for encryption and the private key for decryption. The private key is used only for producing digital signatures, and I'm not certain that the private key can even be used for bulk encryption, I'm still a little unclear on this point with respect to the RSA algorithm. Sincerely, Jason Coombs jasoncat_private -----Original Message----- From: Chris Matthews [mailto:chrisat_private] Sent: Wednesday, January 08, 2003 4:14 AM To: 'Frank Knobbe' Cc: secprogat_private Subject: RE: PGP scripting... -----Original Message----- From: Frank Knobbe [mailto:fknobbeat_private] .... >So once the data has been encrypted on that box, the statement "If the >system is compromised, they have all the data they > need to get all the data." is not true since all they can get is the encrypted data. .... >Regards, >Frank <snip> I believe the original question involved more of a dynamic modification of data on the machine's harddrive. If this is the case, and automatic encryption/decryption would require the public/private keys. Another thought just occurred to me for Andrew: Which key is being used to encrypt the data? If the public key is being used (and bear with me; my pgp theory is foggy this morning :), then technically anyone that has that public key can corrupt your encrypted data. If the private key was used, then anyone with the public key can easily decrypt it. This means that both keys need to be kept "secret", or am I mistaken on this? Perhaps you should propose to your client a reevaluation of what exactly you're trying to protect and then try to find an encryption solution that more closely matches your requirements. Cheers, Chris
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