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Type Based Distributed Access Control

Explore Type-Based Distributed Access Control presented by Dominic Duggan to control data distribution using decentralized label models, local access control, and key-based approaches. Discuss formal semantics and language innovation for secure data sharing.

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Type Based Distributed Access Control

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  1. Type Based Distributed Access Control Dominic Duggan Stevens Institute of Technology Joint work with Tom Chothia (Stevens) and Jan Vitek (Purdue) D. Duggan

  2. Motivation • Our aim is to use types to place conditions on how data may be distributed. • Consider a computer with public and private data: D. Duggan

  3. Talk outline • Review: Decentralized Label Model (DLM) • Local Access Control • Key Based Decentralized Label Model (KDLM) • Distributed Access Control and Cryptography • Formal Semantics • Jeddak: A Language with Distributed Access Control • Conclusions and Further Work D. Duggan

  4. Local Access Control • Local Access Control restricts access to data. • Any read or write attempts are dynamically checked. • There are no restrictions on authorized copies of data. D. Duggan

  5. Decentralized Label Model (DLM) • Program variable x • Has typeint • Has label with policies • Bob : {bob, jane, mike} • Mary : {bob, jane, mary} • Is accessible by bob and jane • Access control checked by type checking D. Duggan

  6. DLM • Data is protected by its type. • Each attempt to copy data is statically checked at compile time. • Copies of data have the same type and hence the same protection. • Data sent outside the type checked area is no longer protected. D. Duggan

  7. Declassification in the DLM • Data has type {L1, L2, L3} int • L1 = bob : { bob, jane } • L2 = mary : { bob, jane, mary } • L3 = jane : { jane, tim} • Only Jane can access data • L3  jane : { jane, tim, bob} • Now Jane and Bob can access the data Jane Bob Mary Tim D. Duggan

  8. Talk outline • Review: Decentralized Label Model (DLM) • Local Access Control • Key Based Decentralized Label Model (KDLM) • Distributed Access Control and Cryptography • Formal Semantics • Jeddak: A Language with Distributed Access Control • Conclusions and Further Work D. Duggan

  9. Application Communication Security Communication Security Communication Communication Network Minimize the Trusted Computing Base DLM KDLM Application Protocol Network D. Duggan

  10. KDLM • As with the DLM data is protected by its type. • But the data can also be protected by encryption. • Encryption protects data leaving the trusted area. • Keys are protected in the same way as data. D. Duggan

  11. KDLM Bob Alice Eve D. Duggan

  12. KDLM: Connecting Keys and Access Restrictions • Key names have policies (ACLs) • K has policy: Joe : {Jane, Mike, Sam} • Public-private key pair for key name • Private key protected by access restrictions • Labels are sets of key names • Access restricted to intersection of policies (ACLs) D. Duggan

  13. B A B A KDLM: Declassifying Encrypted Data Alice Bob A D. Duggan

  14. K3 K1 Declassification in the KDLM K3 has policy jane : {jane } K2 has policy:mary : {bob,jane,mary} Jane creates certificate for Bob: K1 declassifies K3 K1 has policy: bob : {bob, jane} Bob Jane K3 K1 K2 K1 K2 Mary {K1, K2, K3} Encrypted(int) K2 D. Duggan

  15. Declassification Certificates Key & Policy: K : skey[ bob : {mary,sam,bob} ] Label: {K1, K2, … ,Kn} Labelled Type: T{K1, K2, …,Kn} Declassification Cert Types: K1 declassifies K2 K1K2 D. Duggan

  16. Talk outline • Review: Decentralized Label Model (DLM) • Local Access Control • Key Based Decentralized Label Model (KDLM) • Distributed Access Control and Cryptography • Formal Semantics • Jeddak: A Language with Distributed Access Control • Conclusions and Further Work D. Duggan

  17. Arities, Kinds A ::= Prin A ::= SKeyF[P:{P1…Pk}] A ::= IKeyF[P:{P1…Pk}] A::= Type Flags F ::= Virtual F ::= Actual Key names, Principals, Types K,P,T ::= k, p, t K,P,T ::= DecKeyK K,P,T ::= EncKeyK K,P,T ::= AuthKeyK K,P,T ::= SignKeyK K,P,T ::= K1 reclassifies K2 K,P,T ::= E{LT} K,P,T ::= S{LT} K,P,T ::= ChanLT K,P,T ::= t:A LT L ::= {K1,…,Km} LT ::= [T]L1,L2 Kinds, Types, Labels D. Duggan

  18. E ::= newKey k:A {e} E ::= newKey k:A (a+:LT1, a-:LT2) {e} E ::= reclassifyCertK1,K2() E ::= reclassifyCertK1,K2(e) E ::= chainK1,K2,K3(e1,e2) E ::= encryptK(e1,….,ek,e) E ::= decryptK1,K2(e1,…,ek,e) E ::= signK1,K2(e1,…,ek,e) E ::= authK(e1,…,ek,e) E ::= x, y, z, w E ::= a, b, c, n E ::= new(n:LT){e} E ::= fork{e} E ::= send(e1,e2) E ::= receive(a) E ::= reclassifyK1,K2(e1,e2) E ::= packt:ALT(K,e) E ::= unpack e1 to k:A(x:LT){e2} Expressions D. Duggan

  19. Types, Principals, Key Names type skey[P:{P1…Pk}] prin decKeyK K encKeyK P int k- 3 k+

  20. Key Names • Basically names of policies P:{P1,…,Pk} • Exist at the type level • May be: • Actual, i.e., associated public-private key pair at run-time • Virtual, i.e., only compile-time D. Duggan

  21. Why Key-Based DLM? • Suppose we added reclassification certs to DLM e1 has label {Joe:{Mary,Sue}} e2 has label {Joe:{Mary,Sue}} • Joe can declassify e1’s label: declassify ({Joe:{Mary,Sue,Sam}}, e1) • Suppose Joe issues certificate: Joe:{Mary,Sue,Sam} declassifies Joes:{Mary,Sue} • Then e2 can also be declassified! D. Duggan

  22. Why Key-Based DLM? • Some form of structural equivalence/inclusion on labels is still needed e1 has label L1 e2 has label L2 e ? e1 : e2 has label L1 L2 • Who would own result label if it was named? D. Duggan

  23. Talk outline • Review: Decentralized Label Model (DLM) • Local Access Control • Key Based Decentralized Label Model (KDLM) • Distributed Access Control and Cryptography • Formal Semantics • Jeddak: A Language with Distributed Access Control • Conclusions and Further Work D. Duggan

  24. Jeddak • Extends Java with • Principals • Key names • Labels and policies D. Duggan

  25. Talk outline • Review: Decentralized Label Model (DLM) • Local Access Control • Key Based Decentralized Label Model (KDLM) • Distributed Access Control and Cryptography • Formal Semantics • Jeddak: A Language with Distributed Access Control • Conclusions and Further Work D. Duggan

  26. Summary • KDLM for Distributed Access Control • Benefit of Type-Based Approach: Access Checking at compile-time • Lightweight access control for accountable systems • Extended to “compile-time” crypto D. Duggan

  27. Related Work • Information flow and type systems • Denning • Volpano and Smith • Pottier (Flow Caml) • Information flow and access control • Stoughton • Heintze and Riecke, • Myers, Liskov (DLM) • Myers, Zdancewic (JIF) • Banerjee and Naumann • Types and security protocols • Abadi • Gordon and Jeffreys • Pierce and Li • Duggan (Crypto Types) D. Duggan

  28. Questions? D. Duggan

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