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Security Solutions for RESCUE

Security Solutions for RESCUE. Jason E. Holt isrl@lunkwill.org Brigham Young University Internet Security Research Lab isrl.cs.byu.edu. Logcrypt: forward security. Forward security: If a resource is secure at time t, it will remain secure at all t’>t. Example: ephemeral modes in TLS.

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Security Solutions for RESCUE

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  1. Security Solutions for RESCUE Jason E. Holt isrl@lunkwill.org Brigham Young University Internet Security Research Lab isrl.cs.byu.edu

  2. Logcrypt: forward security • Forward security: If a resource is secure at time t, it will remain secure at all t’>t. • Example: ephemeral modes in TLS

  3. Logcrypt: preliminaries • Cryptographic hash function: • Arbitrary size inputs, constant size output (usually 128-512 bits) • Preimage resistant • Collision resistant • Hash chain: s1=h(s), s2=h(s1), s3=h(s2)…

  4. Logcrypt: forward security • Securely record the initial public or secret value • Derive new secrets from the initial secret • Use a secret to MAC/encrypt each piece of incoming data • Delete secrets immediately after use • Verifiers later check data against initial value

  5. Symmetric MAC/encrypt with Logcrypt

  6. Symmetric MAC/encrypt with Logcrypt

  7. Public verification with Logcrypt

  8. Public verification from IBE • Identity Based Encryption • Private Key Generator (PKG) has a public/private value • PKG issues private keys corresponding to strings like isrl@lunkwill.org to users • Anyone can generate the public key for any string given only the PKG public value • Avoids chicken-and-egg problems, key distribution issues

  9. Maintaining multiple concurrent logs

  10. Logcrypt limitations • Truncation • Metronome entries • Compromise of future entries • Fabrication of an entire log

  11. Logcrypt applications • Anything requiring tamper-evidence • Emergency requisition logs • Accountability for public officials after a disaster • Discourages abuse and helps prevent cover-ups • Corporate bookkeeping

  12. Logcrypt applications • Evidence-gathering devices: • Voice recorders • Still cameras • Video cameras • Uses: • Journalism • Police forensics • Intelligence gathering in hostile territory • Police/military gun-cam • Surveillance cameras

  13. Logcrypt applications • System logs • Like Tripwire for system logs • Could automatically email initial secret to external system at install time • Logs can be verified on an external secure machine, or by rebooting to a known secure OS

  14. Hidden Credentials • Traditional trust negotiation: • Resource request / policy disclosure / credential disclosure / resource delivery • Hidden credentials: • Public-key encryption function which takes a policy instead of a public key • E(M, “Alice: Secret clearance” OR “Alice: TOP Secret clearance”)

  15. Hidden Credentials • Reduces network traffic • Instead of 2 full round trips (request/policy/credential/delivery), a single message suffices • Applications: • Policy enforcement in courier networks • Delivery of resources before a disaster

  16. Hidden Credentials • Solves the going-first problem • Usually, one party must show the first credential • IPSec allows either party to go first • Hidden credentials avoid showing credentials entirely • Applications: • Prevents network scanning and credential harvesting

  17. Hidden Credentials • Resolves policy cycles • Conceals policies from unqualified users • Credentials need never be shown

  18. Other Work • Content-triggered trust negotiation • Policies created on-the-fly by classifying data (eg., documents with agent names are always top secret) • Phishing Warden • Surrogate trust negotiation • Mobile devices refer others to a secure central repository • Central repository could change policies without contacting device • THOR: The Hybrid Online Repository

  19. Thoughts on Privacy • Identification is useful between peers • Pseudonymous and reputation systems • Identification and surveillance are dangerous when applied to subordinates • 1984, McCarthyism • Psychological tendency to act in expected ways • Creates a fear and accusation culture • Thwarts risk-taking • Cambodian holocaust

  20. Thoughts on Privacy • Free governments work by subverting the traditional top-down government • Ability to hold government responsible is critical • Transparency is thus an absolute requirement for government processes • Intra-government behavior (senate ethics) • Applications of power (due process, Geneva Convention)

  21. Thoughts on Privacy • Security systems should focus privacy downward, and accounting integrity upward • Privacy is not the opposite of security • Technologies should focus on detecting bad behaviors, not identifying potential criminals

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