Providing Security with Insecure Systems

Providing Security with Insecure Systems

Providing security with insecure systems Andrew Odlyzko School of Mathematics and Digital Technology Center University of Minnesota http://www.dtc.umn.edu/~odlyzko 1 AO 8/03 University of Minnesota Motivation and Outline: • Basic question: What is the role of cryptography and security in society? – Why haven’t cryptography and security lived up to their promise? – Is the future going to be any better? • Main points: – Strong economic, social, and psychological reasons for insecurity – Chewing gum and baling wire will continue to rule – Not absolute security but “speed bumps” – New design philosophy and new research directions 2 AO 8/03 University of Minnesota Security pyramid: users systems protocols algorithms 3 AO 8/03 University of Minnesota Half a century of evidence: •People cannot build secure systems •People cannot live with secure systems 4 4 AO 8/03 University of Minnesota Honor System Virus: This virus works on the honor system. Please forward this message to everyone you know and then delete all the files on your hard disk. Thank you for your cooperation. 5 AO 8/03 University of Minnesota Major problem with secure systems: • secretaries could not forge their bosses’ signatures 6 AO 8/03 University of Minnesota Proposed solution: •Build messy, not clean •(Lessons from past and now) •(Related to “defense in depth,” “resilience.” …) 7 7 AO 8/03 University of Minnesota The dog that did not bark: • Cyberspace is horribly insecure • But no big disasters!!! 8 8 AO 8/03 University of Minnesota The Big Question: •Why have we done so well in spite of insecurity? •Will this continue? •What can we learn? 9 9 AO 8/03 University of Minnesota Key point: • security is not the goal, just an enabler 10 AO 8/03 University of Minnesota Civilian Cryptography of last 30 years: • huge intellectual achievements, based on (and providing stimulus for) mathematics: – integer factorization – lattice basis reduction – probability – elliptic and hyperelliptic curves – algebra – … • limited by human nature 11 AO 8/03 University of Minnesota Human vulnerabilities: • Nigerian 419 scam • “social engineering” • ... 12 AO 8/03 University of Minnesota More general puzzle: Prosperity and appalling innumeracy •confusing millions with billions •most spreadsheets flawed •peer-reviewed papers with incorrect statistical reasoning 13 13 AO 8/03 University of Minnesota Do not expect improvement: teaching people about security won’t help: • growth in ranks of users of high tech • proliferation of systems and devices Improvements in usability of individual systems and devices to be counteracted by growth in general complexity 14 AO 8/03 University of Minnesota 1980s: the “Golden Age” of civilian cryptography and security 15 AO 8/03 University of Minnesota 1980s: the “Golden Age” of civilian cryptography and security But also: the “Golden Age” of fax, including fax signatures 16 AO 8/03 University of Minnesota 1980s: the “Golden Age” of civilian cryptography and security But also: the “Golden Age” of fax, including fax signatures Now : deposits of scanned, emailed checks! 17 AO 8/03 University of Minnesota Why does a fax signature work? • Hard to do serious damage with a single forged fax • Fax usually just one of many elements of an interaction (involving heterogeneous elements, such as phone calls, emails, personal meetings, ...) The role of a fax signature has to be viewed in the context of the entire transaction. (And it is not used for definitive versions of large contracts, ...) 18 AO 8/03 University of Minnesota Search for definition of a digital signature hampered by lack of definition of ordinary signature: validity of ordinary signature depends on a variety of factors (such as age of signer, whether she was sober, whether she had a gun pointed at her head, whether the contract is allowed by law, ...) 19 AO 8/03 University of Minnesota Human space vs. cyberspace in technologists’ view: •separate •cyberspace a new world •cyberspace to compensate for defects of human space 20 20 AO 8/03 University of Minnesota Cold dose of reality: •human space and cyberspace intertwined •human space compensates for defects of cyberspace 21 21 AO 8/03 University of Minnesota The role of cyberspace is increasing, and attacks and other action in cyberspace are faster and more far-reaching than in physical • Partial Solutions: Speed bumps • Example: e-voting – Untrustworthy electronic systems compensated by printed record of vote 22 AO 8/03 University of Minnesota Quantifiable benefits of (incomplete) security: 23 AO 8/03 University of Minnesota Advantages of messy: April 20, 2010 story about Apple • Apple claim: “jailbreaking iPhone OS major source of instabilities, disruption of service” • Does Apple want clean, modular OS? • (incentives, incentives, …) 24 AO 8/03 University of Minnesota If you can barely keep your system running: – how useful will it be to your opponent? 25 AO 8/03 University of Minnesota Contrarian lessons for the future: •learn from spammers, phishers, •build messy and not clean – create web of ties to other systems – permanent records 26 26 AO 8/03 University of Minnesota Speed of light vs. effective speed of change • "Internet time" a key misleading myth of the bubble • diffusion of information (even security holes) not instantaneous • "hiding in plain sight" 27 AO 8/03 University of Minnesota Contrarian lessons for the future (cont’d, in detail): • security through obscurity • code obfuscation, “spaghetti code,” • “least expressive languages” • rely on bad guys’ human failings • law and lawyers 28 28 AO 8/03 University of Minnesota Further data, discussions, and speculations in papers and presentation decks at: http://www.dtc.umn.edu/~odlyzko 29 29 AO 8/03 University of Minnesota.

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