-----BEGIN PGP SIGNED MESSAGE----- In <199706110235.VAA04670@manifold.algebra.com>, on 06/10/97 at 09:35 PM, ichudov@algebra.com (Igor Chudov @ home) said:

Dr.Dimitri Vulis KOTM wrote:

...

Ray Arachelian <sunder@brainlink.com> writes:

...

Passphrases can be memorized. 4mm DAT tapes hold several gigs and are tiny. Ever see one? Fits in your pocket. It's smaller that an audio cassette. Fairly easy to guard, but, if your data is backed up in encrypted form (cyphertext), and not clear text, you don't even need to bother protecting the tape. (That is unless your backup software uses a weak cypher as most tend to do.) [FYI: Your knowledge of tape technologies is severly lacking. 4mm tapes hold 2-4Gb. Exabytes 5Gb-10Gb. Mamouth Exabytes (same size as 8mm camcorder video tapes, smaller than audio cassettes) hold as much as 40Gb in a very small form factor.]

I'm actually thinking of getting a pair of 4mm tape drives to replace my existing backup system (very old drives that use DC 600As; only .25GB / drive, pretty slow, no NT drivers; time to upgrade)

I wonder: if the data is well-encrypted, wouldn't it make the compression pretty ineffective?

You can compress before the encryption (if the encryption algorithm does not do compression).

tar cvfz - /directory | Encrypt > /dev/ftape

or something like that.

Another thing to worry about is being able to at least partially restore data if one or several blocks get corrupted.

Well for backup purposes one would probably want to do their encryption on a block size < file size. As an example for a 1M file you could encrypt it as 10 seperate 100k blocks (or any suitable block size) rather than encrypting the entire file in one block. I have programs on my system that will do this for me but it would be best if all of this was built into the backup software. Myself I don't use tape. I use mirrored HD's and MO's & CD for short & long term archives. - -- - --------------------------------------------------------------- William H. Geiger III http://www.amaranth.com/~whgiii Geiger Consulting Cooking With Warp 4.0 Author of E-Secure - PGP Front End for MR/2 Ice PGP & MR/2 the only way for secure e-mail. OS/2 PGP 2.6.3a at: http://www.amaranth.com/~whgiii/pgpmr2.html - --------------------------------------------------------------- -----BEGIN PGP SIGNATURE----- Version: 2.6.3a Charset: cp850 Comment: Registered_User_E-Secure_v1.1b1_ES000000 iQCVAwUBM567949Co1n+aLhhAQGm1AQAlmPPWerzMnltKwo0wyqD2eKiABc5pr1u InvkvQoi9F3bvc8HXi/qOVZoDU49fmBWPmObz425pRNz412ilnlaUNn+nS2QhtdS o+SB/TQWaJ8afwxdQr3N+aUyTCgxFEQjzNE1rsJF68/eZK5pxii5zbn/NkG1RiYx 3B340rEWGEk= =5Dqc -----END PGP SIGNATURE-----