Re: Packages to remove from frozen
On Thu 09 Mar 2000, Jacob Kuntz wrote: > isn't the problem here that the server is misrepresenting itself? a one bit > difference may not make a less secure key, but it could quite possibly be an > indication of some deception. i worry that altering the client to ignore > this type of error will only open us up to attack, be it man-in-the-middle > or otherwise. Warning: my crypto knowledge is pretty poor. Someone somewhere in this thread said that the problem was that the old ssh could generate a key that had the MSbit off, and that was the cause of these messages. I'm now thinking: if the MSbit *MUST* be set, how does that increase the security? N bits of key is no less secure than N+1 bits where you know the value of one bit. Isn't openssh simply confused in this case? I myself notice that openssh complains about half the time when connecting to a random number of different hosts (I connect daily to a random 5-10 systems out of a collection 700 hosts (each running ssh 1.2.17), which IMHO means the sample is quite random, but then statistics lessons was a long time ago). Paul Slootman -- home: [EMAIL PROTECTED] http://www.wurtel.demon.nl/ work: [EMAIL PROTECTED] http://www.murphy.nl/ debian: [EMAIL PROTECTED] http://www.debian.org/ isdn4linux: [EMAIL PROTECTED] http://www.isdn4linux.de/
Re: Packages to remove from frozen
isn't the problem here that the server is misrepresenting itself? a one bit difference may not make a less secure key, but it could quite possibly be an indication of some deception. i worry that altering the client to ignore this type of error will only open us up to attack, be it man-in-the-middle or otherwise. Ben Armstrong ([EMAIL PROTECTED]) wrote: > On Thu, 9 Mar 2000, Junichi Uekawa wrote: > > Isn't it that to decrypt 1024 key takes double the amount of > > CPU time than decrypting 1023 key, as long as there is no other > > method than brute-force method of trying every combination. > > > > IMO It is a serious security issue, when the system is half as secure > > and one is not notified. And the person is trying to use a ssh. > > Where 'n' is a "reasonable" amount of time to crack a key using > brute-force, doubling 'n' does not equate to doubling the security of your > system. At the most, you have caused the cracker the minor annoyance of > having to wait twice as long for a result. > > Conversely, if '2n' is an "unreasonable" amount of time to crack a key > using brute-force, halving it to 'n' does not equate to halving the > security of your system. > > In other words, I rely on my ssh keys being several orders of magnitude > more difficult to crack than weaker crypto that is crackable in a > "reasonable" amount of time by brute force. Whether the keys are 1023 bit > or 1024 bit is irrelevant. Both accomplish this goal. > > Ben > -- > nSLUG http://www.nslug.ns.ca [EMAIL PROTECTED] > Debian http://www.debian.org [EMAIL PROTECTED] > [ pgp key fingerprint = 7F DA 09 4B BA 2C 0D E0 1B B1 31 ED C6 A9 39 4F ] > [ gpg key fingerprint = 395C F3A4 35D3 D247 1387 2D9E 5A94 F3CA 0B27 13C8 ] > > > > -- > To UNSUBSCRIBE, email to [EMAIL PROTECTED] > with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] > -- (jacob kuntz)[EMAIL PROTECTED] [EMAIL PROTECTED],underworld}.net (megabite systems) "think free speech, not free beer."
Re: Packages to remove from frozen
On Thu, 9 Mar 2000, Junichi Uekawa wrote: > Isn't it that to decrypt 1024 key takes double the amount of > CPU time than decrypting 1023 key, as long as there is no other > method than brute-force method of trying every combination. > > IMO It is a serious security issue, when the system is half as secure > and one is not notified. And the person is trying to use a ssh. Where 'n' is a "reasonable" amount of time to crack a key using brute-force, doubling 'n' does not equate to doubling the security of your system. At the most, you have caused the cracker the minor annoyance of having to wait twice as long for a result. Conversely, if '2n' is an "unreasonable" amount of time to crack a key using brute-force, halving it to 'n' does not equate to halving the security of your system. In other words, I rely on my ssh keys being several orders of magnitude more difficult to crack than weaker crypto that is crackable in a "reasonable" amount of time by brute force. Whether the keys are 1023 bit or 1024 bit is irrelevant. Both accomplish this goal. Ben -- nSLUG http://www.nslug.ns.ca [EMAIL PROTECTED] Debian http://www.debian.org [EMAIL PROTECTED] [ pgp key fingerprint = 7F DA 09 4B BA 2C 0D E0 1B B1 31 ED C6 A9 39 4F ] [ gpg key fingerprint = 395C F3A4 35D3 D247 1387 2D9E 5A94 F3CA 0B27 13C8 ]
Re: Packages to remove from frozen
In Wed, 8 Mar 2000 11:10:11 -0500, de profundis Michael Stone <[EMAIL PROTECTED]> cum veritas scribat mstone> Are you really convinced that the security of a 1023 bit key is so much mstone> worse than the security of a 1024 bit key that any amount of effort mstone> necessary to transition to a new 1024 bit key is justified? In the Isn't it that to decrypt 1024 key takes double the amount of CPU time than decrypting 1023 key, as long as there is no other method than brute-force method of trying every combination. IMO It is a serious security issue, when the system is half as secure and one is not notified. And the person is trying to use a ssh. --- dancer, a.k.a. Junichi Uekawa Dept. of Knowledge Engineering and Computer Science, Doshisha University. ... Long Live Free Software, LIBERTAS OMNI VINCIT.
Re: Packages to remove from frozen
On Wed, Mar 08, 2000 at 09:18:06AM -0500, Branden Robinson wrote: > Use the Source, Luke. Quit whining and start coding. Why? On hosts where this is an issue, f-secure's ssh does the job just fine. (Not to mention that I don't live in a free country and can't work on ssh...) -- Mike Stone pgpQc9EIx2b7L.pgp Description: PGP signature
Re: Packages to remove from frozen
On Wed, Mar 08, 2000 at 08:56:34AM -0600, Nathan E Norman wrote: > Eh, well, it is correct[1] behavior to toss out an error message in this > case since it's notifying you of a *security* problem. In fact, it's > telling you that the server key is half as secure as the server claims > it is. But you *don't* get informed about what the server claims the key is unless you request verbosity. This isn't about displaying wrong info versus displaying right info. This is about displaying extra information for no reason. If the notice that the server was offering an invalid key length came in verbose mode, that would be great; if you got a warning when you first accept the key, that would be useful. What does seeing the message at every login buy you? > If you and your users don't care about security then I'm sure the > error is a real pain in the ass. Of course, if security isn't an > issue then you really don't need to use ssh at all. Are you really convinced that the security of a 1023 bit key is so much worse than the security of a 1024 bit key that any amount of effort necessary to transition to a new 1024 bit key is justified? In the overall scheme of things, that one bit is *not* a high-priority security problem. Changing keys around and getting users into the habit of replacing host keys is a *bigger* security problem than that stupid bit. -- Mike Stone pgpOaT7MmEkRB.pgp Description: PGP signature
Re: Packages to remove from frozen
On Tue, Mar 07, 2000 at 11:26:12PM -0500, Michael Stone wrote: > On Tue, Mar 07, 2000 at 03:13:36PM -0800, Joey Hess wrote: > > Michael Stone wrote: > > > Not very backward-compatible, is it? In some environments it's desirable > > > to have the software behave the same on every platform; even if it's > > > buggy, the bugs need to be consistent. > > > > This is linux. We break backwards compatability if we have to do do things > > *right*. > > How is it right to spit out an error message on every connection that > adds nothing to most people's use of the product? Especially when there > exists a verbose mode for people who want lots of gory details about the > efficacy of their connection? SSH doesn't tell me the key length of > connections *except* in this one case--which is not consistent, and > which is not unambiguously "*right*" behavior. Eh, well, it is correct[1] behavior to toss out an error message in this case since it's notifying you of a *security* problem. In fact, it's telling you that the server key is half as secure as the server claims it is. If you and your users don't care about security then I'm sure the error is a real pain in the ass. Of course, if security isn't an issue then you really don't need to use ssh at all. Generally you complain about issues that have relevance. I think you've missed on this one. Cheers, -- Nathan Norman "Eschew Obfuscation" Network Engineer GPG Key ID 1024D/51F98BB7http://home.midco.net/~nnorman/ Key fingerprint = C5F4 A147 416C E0BF AB73 8BEF F0C8 255C 51F9 8BB7 [1] "Right" describes a direction, specifically the one opposite "left". pgpFY4jPH9kRJ.pgp Description: PGP signature
Re: Packages to remove from frozen
On Tue, Mar 07, 2000 at 11:26:12PM -0500, Michael Stone wrote: > How is it right to spit out an error message on every connection that > adds nothing to most people's use of the product? Especially when there > exists a verbose mode for people who want lots of gory details about the > efficacy of their connection? SSH doesn't tell me the key length of > connections *except* in this one case--which is not consistent, and > which is not unambiguously "*right*" behavior. I disagree with your analysis, but nevertheless... Use the Source, Luke. Quit whining and start coding. -- G. Branden Robinson|A celibate clergy is an especially good Debian GNU/Linux |idea, because it tends to suppress any [EMAIL PROTECTED] |hereditary propensity toward fanaticism. roger.ecn.purdue.edu/~branden/ |-- Carl Sagan pgpZfjGUNDsxY.pgp Description: PGP signature
