Over the past year officials of various governments have expressed a desire to limit encryption or require backdoors to allow government spying (FBI director James Comey, UK Prime Minister David Cameron, US President Barack Obama). This is misguided.
The road to hell is paved with good intentions.
Encrypted communication is hard enough as it is
Considering the number of severe vulnerabilities in SSL/TLS discovered over the past five years I’m surprised https is even still useful. Building encrypted communication software is difficult. Requiring it to be intentionally weakened in specific ways will lead to an increase in unintentional bugs and less secure software.
(This paragraph added eight hours after initial posting:) There’s an underlying question of how feasible it is to add a backdoor to a given encrypted system. When looking at low level encryption protocols it’s potentially impossible. For example, trying to add a backdoor to PGP would fundamentally change PGP. It would no longer be PGP. For a higher level encryption system where encrypted messages transit through an intermediary, perhaps the system could be changed so that messages transit through a government-controlled system, and perhaps the protocol could be changed such that the intermediary decrypts then re-encrypts the message. While these types of changes are feasible, they add complexity to the system. Complexity reduces reliability of the system as a whole and increases the cost of maintenance and initial development.
You can’t stop criminals from using encryption without backdoors
Encryption software without backdoors already exists. Requiring backdoors in a few countries won’t cause this software to stop existing. It won’t prevent cryptographers and software developers in other countries from developing stronger encryption products. Criminals in the US will continue to be able to use strong encryption software regardless of any law preventing it. Making strong encryption illegal reduces the security for those of us with good intentions while acting as only a weak deterrent for those with bad intentions.
Backdoors would be used inappropriately
Regardless of whatever strict requirements are placed upon usage of backdoors, they will be abused. Maybe a hacker will break into a government computer and steal a secret decryption key. Maybe a disgruntled government worker will spy on his boss. The exact scenario is immaterial. Time is infinite, abuse is inevitable.
Therefore it’s not helpful to have a conversation about whether a backdoor will or will not be abused. It is only helpful make the best prediction about how much abuse will happen and decide if this amount is tolerable.
Massive data breaches happen quite frequently. I’ll concede that US intelligence agencies have a decent track record so far (though the Chelsea Manning and Edward Snowden leaks are two titanic counterexamples). I’m not optimistic.
Privacy is a requirement for free speech
The Guardian article mentioned above sums it up well, “the right to privacy runs right in parallel to our right for free expression. If you can’t say something to a friend or family member without the fear the government, your neighbour or your boss will overhear, your free expression is deeply curtailed.”
This argument pertains less to backdoors, where presumably a warrant would be required, and more to banning encryption outright, as David Cameron desired.
Encryption for everyone
Encryption, by the way, is pretty important. Without https and without encrypted Wi-Fi anyone within a few hundred feet of your laptop would be able to see everything you’re doing. Every website you open. The contents of every email you send. How much money is in your bank account. People could capture your login credentials and wire transfer all your money to their own account. Trade stock in your brokerage account. Turn off automatic bill pay for your electricity or mortgage. Buy things with your Amazon account.
Personally I place a high value on my privacy and a low value on the potential of intercepting terrorist communication via a backdoor. The dubious benefits of backdoors do not justify the costs.
Tangentially related blog posts from me:
Violating the Fourth Amendment
Should the NSA be allowed to scan our personal email?