On Fri, 18 Dec 2009 23:19:43 +0000, Andrew Swallow <am.swallow@btopenworld.com> wrote:>krw wrote: >> On Fri, 18 Dec 2009 02:08:44 +0000 (UTC), Rick Jones >> <rick.jones2@hp.com> wrote: >> >>> In comp.protocols.tcp-ip Mark <makolber@yahoo.com> wrote: >>>>> Passing encrypted video over a satellite network built for >>>>> unencrypted analog video is not a trivial challenge. As far as I >>>>> know, there exists no scheme to do this that has not been broken >>>>> already. The problem is that encryption works partly by diffusing >>>>> information so that no part of the output looks like any part of >>>>> the input. The satellite link is filled with errors and distortion >>>>> that have to be contained to retain adequate video quality. >>>> um,, is that why General Instrument was able to do it did it 15 years >>>> ago for HBO? >>> Is it "known" that the GI stuff (irony :) isn't cracked? >> >> I don't believe anyone suggested using civilian encryption for >> military applications, though it would have been better than nothing. > >AES encryption would have probably beaten the Taliban and the Iranians. >Available in a single chip, or you can use software.Real encryption is pretty cheap. The only complication anymore is key management. No matter what you do that's a problem, so might just as well make the encryption good. Rag heads aren't the only potential enemy.
Re: OT: The Truth About Predator Drones
Started by ●December 18, 2009
Reply by ●December 18, 20092009-12-18
On Fri, 18 Dec 2009 23:34:56 +0000, Andrew Swallow <am.swallow@btopenworld.com> wrote:>krw wrote: >{snip} > >> >> OTOH, it's the US government. I'm backing the dumb-as-a-rock >> explanation. > >Front line tactical radio communication has traditionally been >unencrypted. This is just a continuation of that. However being >digital they are changing that. Also high speed off the shelf >portable encryption may not have been available.Nonsense. It's been available for decades.
Reply by ●December 18, 20092009-12-18
krw wrote:> On Fri, 18 Dec 2009 23:34:56 +0000, Andrew Swallow > <am.swallow@btopenworld.com> wrote: > >> krw wrote: >> {snip} >> >>> OTOH, it's the US government. I'm backing the dumb-as-a-rock >>> explanation. >> Front line tactical radio communication has traditionally been >> unencrypted. This is just a continuation of that. However being >> digital they are changing that. Also high speed off the shelf >> portable encryption may not have been available. > > Nonsense. It's been available for decades.True but tactical in the clear is still used. Andrew Swallow
Reply by ●December 18, 20092009-12-18
On Fri, 18 Dec 2009 06:20:40 +0000 (UTC), glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:> >The original question was on analog video, which is somewhat >harder to encrypt without affecting the picture.Bullshit.
Reply by ●December 18, 20092009-12-18
On Fri, 18 Dec 2009 11:02:41 +0000 (UTC), glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:>In comp.dsp Michael A. Terrell <mike.terrell@earthlink.net> wrote: >(snip) > >> Videocipher-I was digital video & audio. Videocipher-II was analog. > >And then there was the system that adds a sine wave to the >video signal such that the sync is not the lowest level anymore, >and wonders around enough that you won't try watch it. > >-- glenThat was not encryption. That was called "In-band gated sync scrambling".
Reply by ●December 18, 20092009-12-18
On Fri, 18 Dec 2009 10:50:36 -0500, "Michael A. Terrell" <mike.terrell@earthlink.net> wrote:> >glen herrmannsfeldt wrote: >> >> In comp.dsp Michael A. Terrell <mike.terrell@earthlink.net> wrote: >> (snip) >> >> > Videocipher-I was digital video & audio. Videocipher-II was analog. >> >> And then there was the system that adds a sine wave to the >> video signal such that the sync is not the lowest level anymore, >> and wonders around enough that you won't try watch it. > > > > That was 'On TV' or the 'Hamlin' scrambling system on Cable TV. That >was '70s technology.It was called "In band gated sync scrambling".
Reply by ●December 19, 20092009-12-19
On Fri, 18 Dec 2009 19:04:59 -0600, krw <krw@att.bizzzzzzzzzzz> wrote:>On Fri, 18 Dec 2009 00:20:47 -0800, Archimedes' Lever ><OneBigLever@InfiniteSeries.Org> wrote: > >>On Thu, 17 Dec 2009 20:05:07 -0600, krw <krw@att.bizzzzzzzzzzz> wrote: >> >>>On Thu, 17 Dec 2009 17:44:12 -0800 (PST), Mark <makolber@yahoo.com> >>>wrote: >>> >>>> >>>>> >>>>> Passing encrypted video over a satellite network built for unencrypted >>>>> analog video is not a trivial challenge. As far as I know, there >>>>> exists no scheme to do this that has not been broken already. The >>>>> problem is that encryption works partly by diffusing information so >>>>> that no part of the output looks like any part of the input. The >>>>> satellite link is filled with errors and distortion that have to be >>>>> contained to retain adequate video quality. >>>>> >>>>> DS >>>> >>>>um,, is that why General Instrument was able to do it did it 15 years >>>>ago for HBO? >>> >>>It can obviously be done. It just requires different, perhaps less >>>efficient, error correction algorithms which may mean lower S/N >>>required. >> >> Wrong. It just requires MORE FEC. > >AlswasWrong is once again wrong. Surprise everyone!You're an idiot. Most digital links can handle up to 10 percent bit error rate before correction coding fails to fix it.
Reply by ●December 19, 20092009-12-19
On Fri, 18 Dec 2009 19:06:22 -0600, krw <krw@att.bizzzzzzzzzzz> wrote:>Real encryption is pretty cheap. The only complication anymore is key >management. No matter what you do that's a problem, so might just as >well make the encryption good. Rag heads aren't the only potential >enemy.Or simply change the key so often that any brute force hackers will fail to decrypt anything inside any effective time frame.
Reply by ●December 19, 20092009-12-19
On 12/19/2009 12:24 PM, Archimedes' Lever wrote:> On Fri, 18 Dec 2009 19:04:59 -0600, krw<krw@att.bizzzzzzzzzzz> wrote: > >> On Fri, 18 Dec 2009 00:20:47 -0800, Archimedes' Lever >> <OneBigLever@InfiniteSeries.Org> wrote: >> >>> On Thu, 17 Dec 2009 20:05:07 -0600, krw<krw@att.bizzzzzzzzzzz> wrote: >>> >>>> On Thu, 17 Dec 2009 17:44:12 -0800 (PST), Mark<makolber@yahoo.com> >>>> wrote: >>>> >>>>>> Passing encrypted video over a satellite network built for unencrypted >>>>>> analog video is not a trivial challenge. As far as I know, there >>>>>> exists no scheme to do this that has not been broken already. The >>>>>> problem is that encryption works partly by diffusing information so >>>>>> that no part of the output looks like any part of the input. The >>>>>> satellite link is filled with errors and distortion that have to be >>>>>> contained to retain adequate video quality. >>>>>> >>>>>> DS >>>>> um,, is that why General Instrument was able to do it did it 15 years >>>>> ago for HBO? >>>> It can obviously be done. It just requires different, perhaps less >>>> efficient, error correction algorithms which may mean lower S/N >>>> required. >>> Wrong. It just requires MORE FEC. >> AlswasWrong is once again wrong. Surprise everyone! > > > You're an idiot. Most digital links can handle up to 10 percent bit > error rate before correction coding fails to fix it.Generally not. Raw BER for BPSK at 0dB is less than 10 percent, and few codes can operate that far down. Even capacity-approaching codes generally need input error rates higher than that. Can you name a code and what code rate would be required to operate with an input BER of 10e-1? I wouldn't think anyone would use a deep-space code on a satellite because of bandwidth efficiency issues. -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
Reply by ●December 19, 20092009-12-19
Eric Jacobsen wrote:> On 12/19/2009 12:24 PM, Archimedes' Lever wrote: >> On Fri, 18 Dec 2009 19:04:59 -0600, krw<krw@att.bizzzzzzzzzzz> wrote:{snip}>> >> You're an idiot. Most digital links can handle up to 10 percent bit >> error rate before correction coding fails to fix it. > > Generally not. Raw BER for BPSK at 0dB is less than 10 percent, and few > codes can operate that far down. Even capacity-approaching codes > generally need input error rates higher than that. > > Can you name a code and what code rate would be required to operate with > an input BER of 10e-1? I wouldn't think anyone would use a deep-space > code on a satellite because of bandwidth efficiency issues. >Tactical military links to a mobile destination are being specified as static civilian links. An error rate of 1 in 10 on a battle field is far from impossible. The military will simply have to live with losing half their bandwidth to the FEC. The links also suffer badly from block errors - a mixture of motor bike engines and frequency hopping jammers. No need to be paranoid, the jammers have operators who are out to get you. Andrew swallow
