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Re What if Responsible Encryption Back-Doors Were Possible? - Lawfare


From: "Dave Farber" <farber () gmail com>
Date: Sun, 2 Dec 2018 23:58:37 +0900




Begin forwarded message:

From: Charles Arthur <charles.arthur () gmail com>
Date: December 2, 2018 at 6:08:42 PM GMT+9
To: dave () farber net
Cc: ip <ip () listbox com>
Subject: Re: [IP] Re What if Responsible Encryption Back-Doors Were Possible? - Lawfare

There is memory in the system, though the writer of the essay is carefully not using words like Clipper so as to 
argue a priori. 

I was puzzled on seeing that it was written by a senior cryptographer at Microsoft. Then I read it. It’s is a 
carefully argued piece pointing out that this genie has escaped the bottle and isn’t going back. 

The final sentence: ‘Make no mistake: Even if it could be built, “responsible” law enforcement access technology is 
not responsible at all.’

It’s pointing out to those who wish for it that you can’t have a thermodynamic-second-law-violating machine, and that 
it might not be good even if you did. 



best
Charles

On 2 Dec 2018, at 01:37, Dave Farber <farber () gmail com> wrote:


Haven’t we been around this idea many many times like Clipper chip etc

Is there no memory in the system?

Dave

Begin forwarded message:

From: Bob Hinden <bob.hinden () gmail com>
Date: December 2, 2018 7:45:56 JST
To: Dave Farber <dave () farber net>
Cc: Bob Hinden <bob.hinden () gmail com>
Subject: Re: [IP] What if Responsible Encryption Back-Doors Were Possible? - Lawfare

Might as have asked “If pigs could fly”.   IMHO it is not possible to have encryption backdoors that won’t be 
abused beyond their intended users.

Bob

On Nov 29, 2018, at 10:10 PM, Dave Farber <farber () gmail com> wrote:



https://www.lawfareblog.com/what-if-responsible-encryption-back-doors-were-possible

What if Responsible Encryption Back-Doors Were Possible?
This is part of a series of essays from the Crypto 2018 Workshop on Encryption and Surveillance.

One of the fundamental constitutional precepts that the U.S. Supreme Court has recognized is the presumption of 
privacy. This presumption is manifested as limits on government intrusion into the private lives of American 
citizens. But these limits are not an absolute in American jurisprudence, nor are they present in all 
democracies. For instance, my conversation in a public place may be overheard, but there is nothing to stop me 
from taking actions and employing tools to enhance the privacy of my effects and communications. Absent 
extraordinary circumstances, I have a right to hide my artifacts and conceal my conversations, and I may also 
engage the assistance of a third party as an agent in doing so. Manufacturers of curtains and blinds may sell 
their products without building in features that make them transparent to law enforcement authorities; safes may 
be sold without retaining keys or combinations to provide exceptional access against the will of the purchaser; 
and encryption products may be sold that protect the privacy of data without restriction.

Under exceptional circumstances and with appropriate judicial review, law enforcement may be permitted to attempt 
to violate my privacy. But a search warrant is so-named because it grants a right to search—not a guarantee to 
find. Law enforcement authorities may also request and even compel my agent to provide information on any 
assistance rendered to me. But there is no prior restriction on the advice or tools that my agent may offer.

Let us now posit the existence of a responsible exceptional access technology, one that secures and protects the 
privacy of data with encryption, but also provides law enforcement authorities with access to that data. 
“Responsible” here describes a technology that achieves the desired effect of providing designated authorities 
with controlled access to data without creating undue risks of data being released to unauthorized parties. It 
should be noted that data breaches are all too frequent today and that complexity is regarded as the enemy of 
security. Thus, despite the dearth of proposals to provide responsible access and the expert analyses that 
enumerate reasons why it is likely unattainable, let us assume that such technology is possible. The next step is 
to consider the consequences of mandating its use. Even if we could build it, the question remains of whether we 
should build it.

In the current landscape, the security interests of technology vendors and their customers are generally aligned. 
Vendors act as their customers’ advocates. The relationship is, of course, imperfect. There are cases where 
vendors fail to adequately protect their customers and suffer consequences in the marketplace. Just as an 
attorney who provides poor counsel may not fare well, vendors who are careless with their customers’ data may not 
survive. Vendors have incentives to secure their customers’ data, and customers have incentives to purchase 
products and services from vendors who protect them well. Prices are certainly a consideration, and customers 
will not always pay a premium for better security, but all other things being equal, a rational consumer will 
select a vendor that provides better security.

Privacy and security are partners, but they are not interchangeable. An agent who is incented to protect my 
security may also have incentives to violate my privacy. However, when I seek to engage an agent to maintain the 
confidentiality of my data, an agent who does so steadfastly will be more valuable to me than one who protects my 
confidentiality only with caveats and conditions.

Introducing exceptional access technology alters the marketplace by increasing costs and reducing protections. It 
transforms the vendor from its role as an unqualified advocate to that of an equivocal actor who may or may not 
betray the confidence of its customers. The trust relationship is compromised, and vendors are prevented from 
serving as unambiguous and full-throated advocates of their customers and their interests.

If customers can choose between vendors offering products that are otherwise comparable, those that include 
provisions for law enforcement access will be at a competitive disadvantage. To be effective, therefore, all 
comparable products within a market (e.g. all mobile phones purchased or used with the U.S.) must be required to 
incorporate the technology.

A government could ban the sale of curtains and window shades and instead insist that those who want to block the 
view must purchase windows which can be made opaque electronically—with the stipulation that exceptional access 
features allow for the opacity to be overridden remotely. This is not impossible, but it would add significant 
costs, create a risk of windows becoming transparent at inopportune times (either due to malfunction or malicious 
attack), and establish a booming market for fabric stores to sell other materials that happen to be sized to 
perfectly fit windows.

The analogy to encryption is not far afield. The greatest difference may be that encryption technologies are 
virtual and are therefore easier to reproduce and transport. Ciphers that are beyond the ability of governments 
to break are described in detail in millions of textbooks that have been used to teach untold numbers of students 
around the globe.

The point here is that a customer who wants privacy can still utilize a device in which a law enforcement access 
technology has been embedded. A customer need only pre-encrypt sensitive data before using the device. The device 
can then be used precisely as intended, and a second layer of encryption will be applied. If a lawful exceptional 
access process is undergone, only the second encryption layer will be removed—revealing not the clear data but 
instead the pre-encrypted data produced by the customer.

The interesting question is the extent to which vendors will go to facilitate this alternative, and the likely 
answer is that many will go as far as legally permitted. Their customers will demand nothing less. Twenty years 
ago, U.S. regulators used export controls to thwart dissemination of encryption tools. Such tools were classified 
as munitions, and vendors were required to register as arms dealers to export them. This had a chilling effect on 
domestic distribution of encryption tools since U.S. vendors did not want to risk the legal jeopardy that might 
ensue should a single instance of a product be exported—whether inadvertently by vendors themselves or by third 
parties.

Americans could freely import and use products that included strong encryption, and U.S. vendors could not 
effectively compete with these imports. This allowed overseas vendors to be better advocates for U.S. customers 
than domestic vendors. In 2000, the export control regime was largely abandoned due to the harm it caused to U.S. 
vendors and the negative impact on data security. An exceptional access mandate today would sever the advocacy 
that vendors currently offer their customers and do substantial harm to both. The impact would be worse than it 
was in the pre-2000 era, when vendors were simply limited in the kinds of security they were able to offer—not 
required to provide explicit exceptional access.

As we have seen from numerous accounts, law enforcement authorities already have access today to unencrypted 
data. Keyloggers and other malware can be surreptitiously placed on devices of targeted individuals, and tools 
exist to crack open locked mobile phones. These means of access can be resource intensive, but that is a 
desirable property. The plea to mandate exceptional access technology is an attempt to remove these resource 
constraints and enable simple, economical, push-button access. But whether they recognize such or not, what 
officials are seeking when they call for easier access is mass-surveillance capabilities. This may not be their 
intent, but if it is easy and inexpensive to surveil one individual, then surveilling many is affordable and 
manageable, and the temptation will be great.

Americans should have an unfettered right to protect their own data, vendors should have the right to provide 
law-abiding citizens with tools and services to support their rights, and law enforcement authorities should have 
to expend resources when they are authorized to attempt to circumvent these protections. Make no mistake: Even if 
it could be built, “responsible” law enforcement access technology is not responsible at all.

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