Date: Wed, 3 May 2000 10:52:49 -0700 From: "John Howie" <JHowie@msn.com> To: "Andrew J. Korty" <ajk@iu.edu>, <security@freebsd.org> Subject: Re: Cryptographic dump(8) Message-ID: <008401bfb528$7ec82b30$fd01a8c0@pacbell.net> References: <Pine.BSF.4.21.0005031019190.21805-100000@kobayashi.uits.iupui.edu>
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Andrew, Here is a proposal. The observant may know where the idea comes from :-) It is more work than your idea but is more flexible and probably more secure. How it works: 1) Every user has a Public/Private Key pair; 2) When the dump is run a random symmetric key is chosen and the data encrypted with it. For every user who is to be allowed access to the tape, their uid and a copy of the symmetric key which is encrypted with their individual public key is written to a file. The file of users and encrypted keys is written to the tape/filesystem; and 3) When restore is run the user's uid and the encrypted symmetric key are retrieved from the keyfile. The user's private key is used to decrypt the symmetric key which is then used to decrypt the tape. This solution offers many benefits, including (and certainly not limited to): 1) The symmetric key is random, and not easy to guess/break; 2) More than one user can restore the dump without actually knowing the key used to encrypt it; 3) Ability to add/remove permission to restore an encrypted tape. Disadvantages: 1) Requires a PKI; 2) A lot more work to implement that your proposed solution (which works fine). Cheers, john... ----- Original Message ----- From: "Andrew J. Korty" <ajk@iu.edu> To: <security@freebsd.org> Sent: Wednesday, May 03, 2000 8:33 AM Subject: Cryptographic dump(8) > I've just extended dump(8) and restore(8) to encipher dump lists > and inode data with CBC 3DES, leaving the headers as cleartext. > Keys can be entered from the tty or a cleartext file. The > purpose is to safely transport and store dumps containing > sensitive data. > > The question: what is the best way to verify a key handed to > restore(8) to decipher a dump? My best thought so far is to > store a checksum for the dumplist, which is just a bitmap of > inodes on the tape, in its header. When restore tries to > decipher the dumplist it will run its own checksum and compare. > > -- > Andrew J. Korty, Lead Security Engineer > Office of the Vice President for Information Technology > Indiana University > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-security" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
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