axlq <axlq@spamcop.net> wrote:>And getting back to my original question, is it pointless to search >for a secure DSP that fits my needs?It's not pointless. But I'd go for a low-volume, full-custom ASIC with the algorithms in an implant ROM (to thrwart microscopic examination) and enough heavy-duty potting material applied to the chip that it would be difficult to deprocess it and E-beam it. If you instead use a standard DSP chip, even with security measures the adversary already has an idea of how to penetrate it Steve
Snoop-proof DSP: possible?
Started by ●September 26, 2009
Reply by ●October 2, 20092009-10-02
Reply by ●October 2, 20092009-10-02
Steve Pope wrote:> axlq <axlq@spamcop.net> wrote: > >> And getting back to my original question, is it pointless to search >> for a secure DSP that fits my needs? > > It's not pointless. But I'd go for a low-volume, full-custom ASIC > with the algorithms in an implant ROM (to thrwart microscopic > examination) and enough heavy-duty potting material applied to the > chip that it would be difficult to deprocess it and E-beam it. > If you instead use a standard DSP chip, even with security measures the > adversary already has an idea of how to penetrate itYou might incorporate an idea I used back in discrete-IC days. I sanded the type designation on some of the chips, imprinted fake part numbers on their undersides, and bent the leads over backwards. The "opposition" assumed that the conformal coating was the disguise. They gave up when they encountered the real obfuscation because they thought they had already solved the problem by stripping the board. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●October 2, 20092009-10-02
Jerry Avins wrote:> Steve Pope wrote: > >> axlq <axlq@spamcop.net> wrote: >> >>> And getting back to my original question, is it pointless to search >>> for a secure DSP that fits my needs? >> >> >> It's not pointless. But I'd go for a low-volume, full-custom ASIC >> with the algorithms in an implant ROM (to thrwart microscopic >> examination) and enough heavy-duty potting material applied to the >> chip that it would be difficult to deprocess it and E-beam it. >> If you instead use a standard DSP chip, even with security measures >> the adversary already has an idea of how to penetrate it > > > You might incorporate an idea I used back in discrete-IC days. I sanded > the type designation on some of the chips, imprinted fake part numbers > on their undersides, and bent the leads over backwards. The "opposition" > assumed that the conformal coating was the disguise. They gave up when > they encountered the real obfuscation because they thought they had > already solved the problem by stripping the board.There are electric scanners which recognize standard ICs as the matter of seconds. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Reply by ●October 2, 20092009-10-02
Vladimir Vassilevsky wrote:> > > Jerry Avins wrote: > >> Steve Pope wrote: >> >>> axlq <axlq@spamcop.net> wrote: >>> >>>> And getting back to my original question, is it pointless to search >>>> for a secure DSP that fits my needs? >>> >>> >>> It's not pointless. But I'd go for a low-volume, full-custom ASIC >>> with the algorithms in an implant ROM (to thrwart microscopic >>> examination) and enough heavy-duty potting material applied to the >>> chip that it would be difficult to deprocess it and E-beam it. >>> If you instead use a standard DSP chip, even with security measures >>> the adversary already has an idea of how to penetrate it >> >> >> You might incorporate an idea I used back in discrete-IC days. I >> sanded the type designation on some of the chips, imprinted fake part >> numbers on their undersides, and bent the leads over backwards. The >> "opposition" assumed that the conformal coating was the disguise. They >> gave up when they encountered the real obfuscation because they >> thought they had already solved the problem by stripping the board. > > There are electric scanners which recognize standard ICs as the matter > of seconds.Now. That was then. To modern scanners recognize chips by looking at their bellies? Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●October 3, 20092009-10-03
Jerry Avins <jya@ieee.org> wrote:>Vladimir Vassilevsky wrote:>> There are electric scanners which recognize standard ICs as the matter >> of seconds.>Now. That was then. To modern scanners recognize chips by looking at >their bellies?I've had upside-down lead-bent chips on boards I've designed, but not as part of obsfucation -- simply becuase the layout guy had his diagram flipped over... S.
Reply by ●October 3, 20092009-10-03
Steve Pope wrote:> Jerry Avins <jya@ieee.org> wrote: > >> Vladimir Vassilevsky wrote: > >>> There are electric scanners which recognize standard ICs as the matter >>> of seconds. > >> Now. That was then. To modern scanners recognize chips by looking at >> their bellies? > > I've had upside-down lead-bent chips on boards I've designed, > but not as part of obsfucation -- simply becuase the layout guy > had his diagram flipped over...Been there. Done that. :-) Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●October 5, 20092009-10-05
Jerry Avins wrote:> Steve Pope wrote: >> Jerry Avins <jya@ieee.org> wrote: >> >>> Vladimir Vassilevsky wrote: >> >>>> There are electric scanners which recognize standard ICs as the >>>> matter of seconds. >> >>> Now. That was then. To modern scanners recognize chips by looking at >>> their bellies? >> >> I've had upside-down lead-bent chips on boards I've designed, >> but not as part of obsfucation -- simply becuase the layout guy >> had his diagram flipped over... > > Been there. Done that. :-)Which brings to mind the first time I consulted for Industrial Inventions Inc. Its owner (who I knew socially but hadn't known his profession) made specialty electronics for the paper fabrication industry -- corrugated boxes and such. One of his products was a power board to turn solenoids on and off, controlling air cylinders. He did this with a pair of SCRs whose cathodes are grounded. One anode is connected to 180V through a keep-alive resistor. The other is connected with the solenoid coil and fly-wheel diode as its load. A commutating capacitor connects the two anodes. There are four possible states, but in practice, only one SCR is on. Firing the /off/ SCR turns the other off. The design had been used for several years on a variety of machines and worked without trouble. Then on one new machine it didn't work at all. The problem turned out to occur only with a newer model solenoid valve, one that drew less current. One could hear the solenoid pull in, but the SCR wouldn't stay on. The problem was mitigated but not completely solved by making the commutating capacitor ten times larger. Since the capacitor had to withstand voltage of both polarities, large capacitance was a problem. Did I think I could help? I suggested that he connect a diode between the solenoid and the SCR, and add another keep-alive resistor directly to that SCR's anode. When he determined the minimum commutating capacitance needed with the new configuration, it turned out to be about a tenth of what he had been using. What was the insight that let me solve this one over the phone? Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●October 5, 20092009-10-05
On Sat, 03 Oct 2009 09:17:02 -0400 Jerry Avins <jya@ieee.org> wrote:> Steve Pope wrote: > > Jerry Avins <jya@ieee.org> wrote: > > > >> Vladimir Vassilevsky wrote: > > > >>> There are electric scanners which recognize standard ICs as the > >>> matter of seconds. > > > >> Now. That was then. To modern scanners recognize chips by looking > >> at their bellies? > > > > I've had upside-down lead-bent chips on boards I've designed, > > but not as part of obsfucation -- simply becuase the layout guy > > had his diagram flipped over... > > Been there. Done that. :-) > > JerryBeen that layout guy. -- Rob Gaddi, Highland Technology Email address is currently out of order
Reply by ●October 5, 20092009-10-05
>On Sep 28, 12:06=A0pm, Jerry Avins <j...@ieee.org> wrote: >> axlq wrote: >> > In article <E_adneyngKqVlCLXnZ2dnUVZ_qydn...@web-ster.com>, >> > Tim Wescott =A0<t...@seemywebsite.com> wrote: >> >> On Sat, 26 Sep 2009 16:59:44 +0000, axlq wrote: >> >>> A business partner has an algorithm applicable to schocastic data,fo=>r >> >>> which it isn't possible to reverse engineer by studying the outputsa=>nd >> >>> inputs. =A0Is it possible to fabricate a custom DSP chip in such awa=>y to >> >>> prevent the underlying algorithm from being extracted, so it canrema=>in >> >>> a trade secret? >> >> >> Nothing will keep a well-funded potential competitor from grindingthe>> >> top off the chip and reverse-engineering (or just outright copying)th=>e >> >> code and/or design. >> >> >> But as others have said, there are chips with security featuresthat'l=>l >> >> make it harder. >> >> >> All you can ever do is make it hard enough to be unprofitable;you'll>> >> never make it impossible. >> >> > That's what I figured. =A0I appreciate all the responses. >> >> > I would have thought these days the chip circuitry might be >> > sufficiently 3-dimensional to make grinding off the top impractical >> > for copying purposes. >> >> You can probe the various parts. After all, with a lot of probing and >> analysis, you can work out the circuit defined by a multi-layercircuit>> board. Some masked ROMs can be read by looking at them under amicroscope=>. >> >> Jerry >> -- >> Engineering is the art of making what you want from things you canget.>>=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=>=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF= >=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF- Hidequ=>oted text - >> >> - Show quoted text - > >I've seen where the circuit is potted in an explosive compound with an >internal photo sensor and battery. Try to disolve away the potting >compound and the circuit explodes - true you may try this in the dark, >but you can put some other gottchas in the circuits that will likely >get disturbed by working in the dark. And if the battery goes flat, >the circuit forgets important data. True not 100% foolproof, but it >does get pretty difficult to beat.Those things have an unpleasant safety record. Steve
Reply by ●October 5, 20092009-10-05
On Oct 5, 12:10�pm, "steveu" <ste...@coppice.org> wrote:> >On Sep 28, 12:06=A0pm, Jerry Avins <j...@ieee.org> wrote: > >> axlq wrote: > >> > In article <E_adneyngKqVlCLXnZ2dnUVZ_qydn...@web-ster.com>, > >> > Tim Wescott =A0<t...@seemywebsite.com> wrote: > >> >> On Sat, 26 Sep 2009 16:59:44 +0000, axlq wrote: > >> >>> A business partner has an algorithm applicable to schocastic data, > fo= > >r > >> >>> which it isn't possible to reverse engineer by studying the outputs > a= > >nd > >> >>> inputs. =A0Is it possible to fabricate a custom DSP chip in such a > wa= > >y to > >> >>> prevent the underlying algorithm from being extracted, so it can > rema= > >in > >> >>> a trade secret? > > >> >> Nothing will keep a well-funded potential competitor from grinding > the > >> >> top off the chip and reverse-engineering (or just outright copying) > th= > >e > >> >> code and/or design. > > >> >> But as others have said, there are chips with security features > that'l= > >l > >> >> make it harder. > > >> >> All you can ever do is make it hard enough to be unprofitable; > you'll > >> >> never make it impossible. > > >> > That's what I figured. =A0I appreciate all the responses. > > >> > I would have thought these days the chip circuitry might be > >> > sufficiently 3-dimensional to make grinding off the top impractical > >> > for copying purposes. > > >> You can probe the various parts. After all, with a lot of probing and > >> analysis, you can work out the circuit defined by a multi-layer > circuit > >> board. Some masked ROMs can be read by looking at them under a > microscope= > >. > > >> Jerry > >> -- > >> Engineering is the art of making what you want from things you can > get. > > =AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF= > > >=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=A�F= > >=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF- Hide > qu= > >oted text - > > >> - Show quoted text - > > >I've seen where the circuit is potted in an explosive compound with an > >internal photo sensor and battery. Try to disolve away the potting > >compound and the circuit explodes - true you may try this in the dark, > >but you can put some other gottchas in the circuits that will likely > >get disturbed by working in the dark. And if the battery goes flat, > >the circuit forgets important data. True not 100% foolproof, but it > >does get pretty difficult to beat. > > Those things have an unpleasant safety record. >True, but the items being protected are highly desirable and thus extreme protection methods being acceptable. Clay
