Blockchain_ver0.5_MIT_security_and Privacy_am_final_upload
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Blockchain and Security – Solving the challenge of Privacy, Identity and Trust discusses key security challenges with blockchain such as identity, privacy, trust, and cryptography. It explores solutions like permissioned blockchains, homomorphic encryption, and zero knowledge proofs to address these issues. The document also examines cases like Silk Road and MtGox that demonstrate security failures with blockchain.
Blockchain_ver0.5_MIT_security_and Privacy_am_final_upload
- 1. Blockchain and Security – Solving the challenge of Privacy, Identity and Trust Anish Mohammed MIT DCI – 25th August 2016
- 2. Blockchain – what makes it unique ● Pseudonmity- The ability that users are not easily identified ● Censorship resistance – gives the ability to bypass authorities ● Decentralised – distributed hence hard to track down
- 3. Blockchain – key security challenges ● Identity- General approach has been to support pseudonyms ● Privacy – Blockchain as a paradigm expects all data to be available ● Trust – Question of trust in a decentralised system
- 4. Blockchain – key security challenges (contd) ● Cryptography – choice of algorithms and parameters not necessarily considered traditional. Also the question of QC resistance brought up by some vendors ● Infrastructure – Generally considering the whole Blockchain ecosystem, esp Bitcoin
- 5. Blockchain and Post Quantum Cryptography ● Shor’s algorithm ● Grover’s algorithm ● Current crop of QC resistant algorithms
- 6. Privacy ● Permissioned Blockchain – having Blockchain which has permission ● Homomorphic encryption – Allowing operations with out revealing content
- 7. Smart Contracts and Privacy ● “The basic idea behind smart contracts is that many kinds of contractual clauses (such as collateral, bonding, delineation of property rights, etc.) can be embedded in the hardware and software we deal with, in such a way as to make breach of contract expensive (if desired, sometimes prohibitively so) for the breacher.” ● “Smart contracts combine protocols, user interfaces, and promises expressed via those interfaces, to formalize and secure relationships over public networks. This gives us new ways to formalize the digital relationships which are far more functional than their inanimate paper-based ancestors” ● “Smart contracts reduce mental and computational transaction costs.” – “Formalizing and Securing Relationships on Public Networks,” Nick Szabo
- 9. Permissioned Blockchain ● Permissioned Blockchain – Bitcoin Blockchain is non-permissioned, nodes could have permission to read or write
- 10. Homomorphic Encryption ● Homomorphic Encryption – the challenge of processing without knowing what is being asked Function f x search query Google search Search results x f(x)
- 11. Homomorphic Encryption ● Homomorphic Encryption – Oct 2008 Craig Gentry came up with solution Function f x Enc(x) Enc(f(x)) search query Search results Google search
- 12. Homomorphic – under multiplication ● Some encryption algorithms already have multiplicative homomorphic properties, e.g. RSA 𝐸 𝑚1 = 𝑚1 𝑒 𝐸 𝑚2 = 𝑚2 𝑒 which implies 𝐸 𝑚1 × 𝐸 𝑚2 = 𝑚1 𝑒 × 𝑚2 𝑒 = (𝑚1 × 𝑚2) 𝑒 = 𝐸(𝑚1 × 𝑚2)
- 13. Homomorphic – under addition ● Other Encryptions were additively homomorphic 𝐸 𝑚1 + 𝐸 𝑚2 = 𝐸(𝑚1 + 𝑚2) Additive Homomorphism
- 14. Enigma – the possible answer from MIT
- 15. MtGox – yet another case
- 16. Provisions – privacy preserving way to prove solvency
- 17. Trust ● Trust model – Bitcoin Blockchain has a distributed model of trust. So everyone trusts everybody else. ● Intermediaries in the ecosystem – real life implementation of Bitcoin ecosystem requires one to trust various intermediaries with varying results.
- 18. Bitcoin/Blockchain – malware ● Malware which mines (steals CPU/GPU cycles) ● Malware which steals Bitcoin from wallets ● Ransomware – accepts Bitcoins to release keys
- 20. Identity ● Identity- General approach has been to support pseudonyms ● Identity verification – strength of verification of identity is as good as onboarding
- 21. Identity – some interesting examples
- 22. Blockchain and graph analysis
- 23. Silkroad – A case of failure
- 24. Smart Contracts – security challenges (moritorium)
- 25. Smart Contracts – security challenges (the hack)
- 26. Other tools - Trusted Computing
- 27. Trust
- 32. Zero Knowledge protocols - properties ● Completeness -If prover is telling the truth, then they will eventually convince the verifier. ● Soundness -Prover can only convince verifier if they're actually telling the truth. ● Zero-knowledgeness -Verifier doesnt learn anything else about prover's solution According to Goldwasser, Micali and Rackoff
- 33. Blockchain and expert opinions
- 34. Dilbert’s take on Security