Crypto to defend chip IP: snake oil or good idea?

[Anne & Lynn Wheeler]

Thor Lancelot Simon wrote:
> I don't get it.  How is there "no increase in vulnerability and threat"
> if a manufacturer of counterfeit / copy chips can simply read the already
> generated private key out of a legitimate chip (because it's not protected
> by a tamperproof module, and the "significant post-fab security handling"
> has been eliminated) and make as many chips with that private key as he
> may care to?
> 
> Why should I believe it's any harder to steal the private key than to
> steal a "static serial number"?

there is no increased vulnerability and threat to existing situation 
where attacker can copy the serial number as it is being read out by 
normal functions. its static data ... along the lines of symmetric 
password ... where the same information that is used to establish the 
authentication is also used to validate the authentication.

the private key scenario doesn't export the private key as part of any 
normal function ... it is generated within the added circuit core, not 
available to processing outside of the added circuit core, and the only 
thing that is normally exposed/exported outside the normal added circuit 
core is the public key and digital signatures.

so the added circuit core is incremental cost for the chip real estate 
for the incremental 20k-40k circuit core. the rest of the associated fab 
and post-fab processing can be reduced to effectively zero ... changing 
the paradigm from a serial number, pin, password symmetrical based 
authentication to an asymmetrical based authentication (for essentially 
no incremental cost).

so an attacker to retrieve the private key ... can't do it by trivial 
evesdropping or readily available processor functions ... instead the 
attacker has to resort to physical invasive techniques on the chip to 
obtain the private key. right away that eliminates all the distance, 
electronic attacks ... reducing the attacks that require physical 
possession of the object.

so now the issue is countermeasure to physical invasive attacks 
requiring physical possession of each chip. so in some of the scenarios 
... one sufficient is to have sufficient physical invasive 
countermeasures that the physical attack will take longer than the 
nominal interval to report physical lost/stolen (invalidating the use of 
the physical object).

another scenario from parameterized risk management ... is to make the 
physical attack more expensive than the associated expected fraudulent 
benefit to the attacker.

the issue is since the serial number is static (and requires symmetrical 
authentication ... same value is used for both establishing 
authentication and verifying authentication) ... and

symmetric authentication mechanisms are vulnerable to a large number of 
attacks other than physical invasive attack on the physical chip
(the argument is nearly identical to the justification of using digital 
signature authentication in lieu of static data pin/password 
authentication which is subject to all sorts of evesdropping and replay 
attacks) ... like peeling physical layers of the chip and using scanning 
electron microscope .... i actually spent some time working at the los 
gatos vlsi lab (bldg. 29) which claims to have pioneered use of scanning 
electron microscope for chip analysis ... not for chip attacks ... but 
as part of debugging initial chips.

so a physical vulnerability issue for something fips140-2 is whether 
there is constant power and countermeasure to physical invasive attack 
can trigger zeroization. there is cost and vulnerability trade-off 
regarding not having constant power and can have a physical attack w/o 
zeroization countermeasure. that is something that shows up as part of 
parameterized risk management.




this is also somewhat related to the security proportional to risk topic
... one such discussion:
http://www.garlic.com/~lynn/2001h.html#61

past posts involving this thread:
http://www.garlic.com/~lynn/aadsm24.htm#49 Crypto to defend chip IP: 
snake oil or good idea?
http://www.garlic.com/~lynn/aadsm24.htm#51 Crypto to defend chip IP: 
snake oil or good idea?
http://www.garlic.com/~lynn/aadsm24.htm#52 Crypto to defend chip IP: 
snake oil or good idea?
http://www.garlic.com/~lynn/aadsm24.htm#53 Case Study: Thunderbird's 
brittle security as proof of Iang's 3rd Hypothesis in secure design: 
there is only one mode, and it's secure
http://www.garlic.com/~lynn/aadsm25.htm#0 Crypto to defend chip IP: 
snake oil or good idea?
http://www.garlic.com/~lynn/aadsm25.htm#1 Crypto to defend chip IP: 
snake oil or good idea?
http://www.garlic.com/~lynn/2006n.html#57 The very first text editor

past posts discussing parameterized risk management issues:
http://www.garlic.com/~lynn/aadsmore.htm#bioinfo3 QC Bio-info leak?
http://www.garlic.com/~lynn/aadsmore.htm#biosigs biometrics and 
electronic signatures
http://www.garlic.com/~lynn/aepay3.htm#x959risk1 Risk Management in AA / 
draft X9.59
http://www.garlic.com/~lynn/aadsm3.htm#cstech3 cardtech/securetech & CA PKI
http://www.garlic.com/~lynn/aadsm3.htm#cstech4 cardtech/securetech & CA PKI
http://www.garlic.com/~lynn/aadsm3.htm#cstech9 cardtech/securetech & CA PKI
http://www.garlic.com/~lynn/aadsm3.htm#kiss2 Common misconceptions, was 
Re: KISS for PKIX. (Was: RE: ASN.1 vs XML (used to be RE: I-D ACTION 
:draft-ietf-pkix-scvp-00.txt))
http://www.garlic.com/~lynn/aepay6.htm#x959b X9.59 Electronic Payment 
standard issue
http://www.garlic.com/~lynn/aadsm12.htm#17 Overcoming the potential 
downside of TCPA
http://www.garlic.com/~lynn/aadsm19.htm#15 Loss Expectancy in NPV 
calculations
http://www.garlic.com/~lynn/aadsm19.htm#44 massive data theft at 
MasterCard processor
http://www.garlic.com/~lynn/aadsm19.htm#46 the limits of crypto and 
authentication
http://www.garlic.com/~lynn/aadsm21.htm#5 Is there any future for 
smartcards?
http://www.garlic.com/~lynn/aadsm21.htm#8 simple (&secure??) PW-based 
web login (was Re: Another entry in the internet security hall of shame....)
http://www.garlic.com/~lynn/aadsm23.htm#1 RSA Adaptive Authentication
http://www.garlic.com/~lynn/aadsm23.htm#27 Chip-and-Pin terminals were 
replaced by "repairworkers"?
http://www.garlic.com/~lynn/aadsm25.htm#1 Crypto to defend chip IP: 
snake oil or good idea?
http://www.garlic.com/~lynn/99.html#235 Attacks on a PKI
http://www.garlic.com/~lynn/99.html#238 Attacks on a PKI
http://www.garlic.com/~lynn/2000.html#46 question about PKI...
http://www.garlic.com/~lynn/2000.html#57 RealNames hacked. Firewall issues.
http://www.garlic.com/~lynn/2005k.html#23 More on garbage
http://www.garlic.com/~lynn/2006g.html#40 Why are smart cards so dumb?

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