Reasons to Support Strong Encryption for a Globally Secure Internet

Professor Peter SwireOhio State University

U.S. Technology Training InstituteWashington, D.C.

April 11, 2011

Overview

• My view – have strong encryption, not weak cybersecurity• Short history of wiretaps, phone & data• U.S. history in 1990s and shift to strong crypto• Objection: “We want the keys”• Objection: “There must be a back door”• Why we don’t want weak cybersecurity– Lack of strong crypto as a security and legal violation

Local switch

Local switch

Wiretap on Copper LinesPhone

call

Phone call

Telecom Company

WIRETAP AT A’S HOUSE OR LOCAL SWITCH

3

Alice

Bob

Local switch

Local switch

Wiretap on Fiber OpticPhone

call

Phone call

Telecom Company

WIRETAP ONLY AT LOCAL SWITCH

3

Alice

Bob

VOICE, NOT DATAMOBILE & LAND

HQ gets downloads

CALEA in U.S.WIRETAP READY

Bob ISP

Alice ISP

%!#&*YJ#$&#

^@%

%!#&*YJ#$&#

^@%

From Voice to Internet

Hi Bob!

Hi Bob!

Internet: Many Nodes between ISPs

Nodes: many, unknown, potentially maliciousWEAK ENCRYPTION = MANY INTERCEPTS

3

Alice

Bob

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^@%

%!#&*YJ#$&#

^@%

%!#&*YJ#$&#

^@%

%!#&*YJ#$&#

^@%

%!#&*YJ#$&#

^@%

%!#&*YJ#$&#

^@%

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^@%

Problems with Weak Encryption

• Nodes between A and B can see and copy whatever passes through

• Brute force attacks became more effective due to Moore’s Law; today, 40 bits very easy to break by many

• From a few telcos to many millions of nodes on the Internet – Hackers– Criminals– Foreign governments– Amateurs

• Strong encryption as feasible and correct answer– Scaled well as Internet users went over one billion

U.S. Experience 1990’s

• Initial inter-agency victory for law enforcement (FBI) and national security (NSA), early-mid 90’s– Clipper Chip – government would have the keys– Fear of loss of ability to wiretap

• Over 5 years of debate, to change in September, 1999– Always had strong crypto within US– Exports were controlled, on idea that crypto = munition– Change to allow strong crypto export, new global norm

(except for a few countries) that strong crypto used on Internet globally

• Why the change to position contrary to view of law enforcement and security agencies?

Crumbling of Weak Crypto Position• Futility of weak crypto rules– Meeting with Senator or Congressman– Start the clock, how long to search for “encryption

download”?• Get PGP or other strong crypto in less than one minute

• In world of weak crypto rules, effect on good guys and bad guys– Bad guys – download PGP, stop the wiretap– Good guys – follow the rules, legitimate actors get their

secrets revealed• Banking, medical records, retail sales• The military’s communications on the Internet,

government agencies, critical infrastructure

Objection – We Want the Keys

• The failure of the Clipper Chip– Idea was that all users of strong crypto would “escrow”

their keys with law enforcement• Advocates for it had various safeguards, e.g., two

people in the government had to agree for the key to be revealed

– Devastating technical arguments against this• Some people didn’t trust the government• If do this for 200 nations worldwide, more people don’t

trust all the governments• Single point of failure – if the databank of keys is ever

revealed, most/all communications can be read

Objection – We Want the Keys

• Even apart from key escrow, is useful to walk briefly through how public key encryption works, to show limits of requests for “we want the keys”

• Basic approach of public key encryption– Other similar terms are Diffie-Hellman, asymmetrical keys– RSA a well-known instance of this approach

• Alice and Bob each have a “public” key that anyone can wrap plaintext with– They each have a “private” key that is the only way to

unwrap the encrypted text (unless someone tries brute force or other attack)

Encrypt

Encrypted message –

Where are the KEYS?Hi Bob!

The KEYS are with the INDIVIDUALS

1

Alice Bob's public key

Bob's private key

– Alice's local ISP

%!#&YJ@$

%!#&YJ@$

Decrypt Hi Bob!

%!#&YJ@$

%!#&YJ@$

– Bob's local ISP

– Backbone provider

Bob

Encrypt

Encrypted message –

Where are the KEYS?Hi Fred!

The KEYS are with the CORPORATIONS

2

Jill at Corporation A

Public key of Corporation B

Private key of Corporation B

– Corporation A's ISP

%!#&YJ@$

%!#&YJ@$

Decrypt Hi Fred!

%!#&YJ@$

%!#&YJ@$

– Corporation B's ISP

– Backbone provider

Fred at Corporation B

Lawful process:(1) Ask Corp A before

encryption(2) Ask Corp B after

decryption

Limits to Getting the Keys

• In many instances, the keys are held by Alice and Bob– No one else has the keys• That can include the software maker• Can be encryption at rest – your laptop– Brickifies if you lose your encryption key, so keep a

backup• Can be encryption in communication– You may be only one with access to the private key,

in some systems select it yourself or it is created by a one-way function where the originator has no access

– Technical experts prefer/insist on this

Objection – Isn’t There a Back Door?

• As with Clipper Chip, law enforcement would love to have a back door• Back door = designed security flaw in the system

– May be that law enforcement only can read (Clipper Chip)– May be that software/service provider can read (they promise security

but keep a secret way in)• Goal of back door:

– All the good guys can get in (and know they can ask for it)– No one else, including bad guys, get in:

• Criminals and their hackers• Foreign governments and spy services• Ph.D. computer experts• White hat hackers – people who detect flaws and tell CERTs and

others about them

The Likelihood of Back Doors?• Let’s think through the likelihood that widely-used strong encryption

actually has back doors for some law enforcement/national security agencies

• My view – much less likely than many people think– Swire writings on when secrecy helps/hurts security– Key point is that secrecy not likely to be successful when there are

many attackers, who can attack repeatedly, and can report successful attacks

• A simpler way to say this: Wikileaks– What likelihood that the FBI has been pervasively using a backdoor,

with knowledge of software/services companies, and it hasn’t leaked since 1999 approval of strong crypto?

– What likelihood that none of the smart Ph.Ds and white hat hackers have ever found an example of this?

– What brand effect on Microsoft (Bit Locker) and other global brands if they promised security and secretly broke it? What penalties for fraud?

Why We Don’t Want Weak Cybersecurity

• Key point so far – weak crypto is weak cybersecurity– A world full of attackers can and will read data sent over the Internet

unless there is strong crypto• U.S., India, and other governments considering the issue of strong crypto

have spoken strongly about the need for strong cybersecurity– Numerous quotes about the need for strong cybersecurity– Critical infrastructure open to attack – Financial system– Medical records and other sensitive personal information

• Including records used in cross-border provision of services

Lack of Strong Crypto as Legal Violation

• Strong crypto increasingly becoming legal requirement– State of Massachusetts computer security law now in effect

• Strict penalties for loss of laptop or other loss of data unless strong encryption in place

– U.S. funding of $19 billion for electronic health records• Rules for reimbursement to medical providers going into effect on

what constitutes “meaningful use” of electronic health records• Major financial incentive to have “meaningful use”• Strong encryption is expected to qualify for funding

– More generally, numerous laws worldwide require cost-effective security measures, on pain of penalties• What is “adequate” protection under E.U. law?• For instance, Gramm-Leach-Bliley safeguards rule for U.S. financial

services• With strong crypto low-cost and pervasive, its absence violates

many laws

Conclusion• In discussion session can address other issues, including:

– Law enforcement concerns that they are “going dark” – in fact they have much more access to intercepts than historically

– Role of lawful intercept and effective legal structure as predicate for trans-border legal process

– The U.S. and why it kept strong crypto despite other legal changes in the U.S. Patriot Act

• In conclusion, complexity and disagreement will continue on how law enforcement and national security agencies can/should have access to communications, with what legal process

• But a simple point – weak encryption at the heart of the Internet is weak cybersecurity

• The debate on this topic took several years in the U.S. – In the end, wide and stable understanding that strong crypto is

essential to do serious business on the Internet– Nothing has shaken that position since the U.S. acceptance of strong

encryption in 1999