Re: Key Security Question

>> My computer went into the shop a few days ago, and I was unable to take
>> my PGP keys off it before it went in.  What are the security risks here?
>> If the repairman chooses to snoop through the files, what would he be
>> able to do with my key pair?  Will I need to revoke the key and make a
>> new one, or will I be relatively safe since he doesn't have my
>> passphrase?

Passphrases are MD5-hashed into 128-bit IDEA keys and used to
encrypt the secret key; there's a "pgpcrack" program out there
that does dictionary-style searches to find if you've got 
wimpy passphrases.  So if your passphrases is "secret", you lose,
but if it's "fjhw;doifvjuc-[09efiu v` 2	4rnhc;ljoipcvjpoiewujfgv;loik"
you're probably pretty safe, unless that's written on the yellow
sticky you left on the side of the PC.

On the other hand, if the "repairman" replaced your pgp executable
with version 2.6.3kgb, which uses your hashed passphrase as the
session key, you're hosed.  Or if he installed a keystroke sniffer,
or added a small radio transmitter to your keyboard, or whatever.
Depends on your threat model.  If you need to be paranoid,
they've already gotten you....

#			Thanks;  Bill
# Bill Stewart, +1-415-442-2215 stewarts@ix.netcom.com
# You can get PGP outside the US at ftp.ox.ac.uk/pub/crypto/pgp
#     (If this is a mailing list, please Cc: me on replies.  Thanks.)

Bill Stewart <stewarts@ix.netcom.com> writes:

> >> My computer went into the shop a few days ago, and I was unable to take
> >> my PGP keys off it before it went in.  What are the security risks here?
> >> If the repairman chooses to snoop through the files, what would he be
> >> able to do with my key pair?  Will I need to revoke the key and make a
> >> new one, or will I be relatively safe since he doesn't have my
> >> passphrase?
>
> Passphrases are MD5-hashed into 128-bit IDEA keys and used to
> encrypt the secret key; there's a "pgpcrack" program out there
> that does dictionary-style searches to find if you've got
> wimpy passphrases.  So if your passphrases is "secret", you lose,
> but if it's "fjhw;doifvjuc-[09efiu v` 2	4rnhc;ljoipcvjpoiewujfgv;loik"
> you're probably pretty safe, unless that's written on the yellow
> sticky you left on the side of the PC.
>
> On the other hand, if the "repairman" replaced your pgp executable
> with version 2.6.3kgb, which uses your hashed passphrase as the
> session key, you're hosed.  Or if he installed a keystroke sniffer,
> or added a small radio transmitter to your keyboard, or whatever.
> Depends on your threat model.  If you need to be paranoid,
> they've already gotten you....

If you're really paranoid, you can boot from a clean floppy and
reinstall everything from your backup tapes. You do have a
contingency plan in case your hard disk goes bad, or gets a
virus, don't you? Well, if you're in doubt, exercise it.

---

Dr.Dimitri Vulis KOTM
Brighton Beach Boardwalk BBS, Forest Hills, N.Y.: +1-718-261-2013, 14.4Kbps

Dr.Dimitri Vulis KOTM wrote:
> Bill Stewart <stewarts@ix.netcom.com> writes:
> > On the other hand, if the "repairman" replaced your pgp executable
> > with version 2.6.3kgb, which uses your hashed passphrase as the
> > session key, you're hosed.  Or if he installed a keystroke sniffer,
> > or added a small radio transmitter to your keyboard, or whatever.
> > Depends on your threat model.  If you need to be paranoid,
> > they've already gotten you....
> 
> If you're really paranoid, you can boot from a clean floppy and
> reinstall everything from your backup tapes. You do have a
> contingency plan in case your hard disk goes bad, or gets a
> virus, don't you? Well, if you're in doubt, exercise it.

And what if the repairman replaces BIOS ROM chips with KGBios?

	- Igor.

ichudov@algebra.com (Igor Chudov @ home) writes:

> Dr.Dimitri Vulis KOTM wrote:
> > Bill Stewart <stewarts@ix.netcom.com> writes:
> > > On the other hand, if the "repairman" replaced your pgp executable
> > > with version 2.6.3kgb, which uses your hashed passphrase as the
> > > session key, you're hosed.  Or if he installed a keystroke sniffer,
> > > or added a small radio transmitter to your keyboard, or whatever.
> > > Depends on your threat model.  If you need to be paranoid,
> > > they've already gotten you....
> >
> > If you're really paranoid, you can boot from a clean floppy and
> > reinstall everything from your backup tapes. You do have a
> > contingency plan in case your hard disk goes bad, or gets a
> > virus, don't you? Well, if you're in doubt, exercise it.
>
> And what if the repairman replaces BIOS ROM chips with KGBios?

On some computers it's possible to add executable code to the boot
sequence without replacing the actual ROM chip because they're
rewritiable. Examples: most Sun boxes; intel motherboards with
'flash bios'.

---

Dr.Dimitri Vulis KOTM
Brighton Beach Boardwalk BBS, Forest Hills, N.Y.: +1-718-261-2013, 14.4Kbps