Cryptography in Bitcoin

Cryptography in Bitcoin

Talk for CryptoParty Singapore 2013
https://cryptoparty.org/wiki/Singapore

Cae2dd246ed83dd458e4ce5f927aa2f7?s=128

U-Zyn Chua

April 15, 2013
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  1. in Bitcoin Cryptography by U-Zyn Chua for Singapore CryptoParty 15

    April 2013
  2. U-Zyn Chua is not Cryptographer Economist

  3. U-Zyn Chua is IT Consultant @ Security enthusiast Bitcoiner

  4. How many... ? Bitcoiner? Knows about Bitcoin? Have no idea

    about Bitcoin?
  5. None
  6. What is Bitcoin? Distributed electronic cash protocol and a unit

    of currency
  7. What is Bitcoin? Satoshi Nakamoto Genesis block on 3 Jan

    2009 “Gone for good” since late 2010
  8. What is Bitcoin?

  9. 1m44s

  10. What makes a currency? Scarce Predictable growth Secure Valuable

  11. Production is halved every 4 years Never more than 21

    million
  12. ~USD 100/Bitcoin

  13. Problems Currency creation Keeps value stable Fraud prevention

  14. Cryptography No central bank No watchdog only No authority

  15. How does Bitcoin work? Public-key cryptography Peer-to-peer network Proof-of-work

  16. Public-key crypto 160-bit hash (SHA-256) 18YCR8bvxLaVCmbgY6eCavF733QDs1sQDT Base58-encoded Generate as many

    as you want 215,000,000,000,000,000,000,000,000,0 00,000,000,000 addresses per capita.
  17. Public-key crypto

  18. Transaction Public & broadcasted http://blockchain.info

  19. Transaction 499335.01317523 1DkyBEKt5S2GDtv7aQw6rQepAvnsRyHoYM 105555.03133700 1933phfhK3ZgFQNLGSDXvqCn32k2buXY8a 79957.03133700 1FeexV6bAHb8ybZjqQMjJrcCrHGW9sb6uF 53000.03133700 16cou7Ht6WjTzuFyDBnht9hmvXytg6XdVT 50259.03133700

    1CfPAfVDe1Br11SkNrk2bEMmMP3bAA5wRr 50130.03133700 13vJZKHKBirruXwmjMaRtakzPQRRHQit1S 50000.03133700 1P3S1grZYmcqYDuaEDVDYobJ5Fx85E9fE9 50000.03133700 1DEpjpftLbsGiCJvJDp2F2quVRnymV8U5Q 47458.03133700 1BBqjKsYuLEUE9Y5WzdbzCtYzCiQgHqtPN 44914.03133700 1MR6pXDZ6gpBVN8n61SqCNF61vU8ZzRu8Y 44512.03133700 1BVA88962SxcymHSfqXSy9F7cgXefi3zgt 40000.03133700 16Ls6azc76ixc9Ny7AB5ZPPq6oiEL9XwXy 40000.03133700 12HddUDLhRP2F8JjpKYeKaDxxt5wUvx5nq 40000.03133700 1cXNTyXj4xPGopfYZNY5xfSM1EPJJvBZV 38058.03133700 1FngtAcZsLfK89MNe7TqzyqVtSype8TiVD 38000.03133700 18Hsgq92AUB1PYLU6MUMQXiwdebaDRo9oQ 35000.00000000 1DAmsh8tHUtH2cVUDMxnDkKr8SaPNkb36h 31000.03133700 12ib7dApVFvg82TXKycWBNpN8kFyiAN1dr 30000.03133700 1MyGwFAJjVtB5rGJa32M6Yh46cGirUta1K Bitcoin richest
  20. Transaction 499335.01317523 1DkyBEKt5S2GDtv7aQw6rQepAvnsRyHoYM 105555.03133700 1933phfhK3ZgFQNLGSDXvqCn32k2buXY8a 79957.03133700 1FeexV6bAHb8ybZjqQMjJrcCrHGW9sb6uF 53000.03133700 16cou7Ht6WjTzuFyDBnht9hmvXytg6XdVT 50259.03133700

    1CfPAfVDe1Br11SkNrk2bEMmMP3bAA5wRr 50130.03133700 13vJZKHKBirruXwmjMaRtakzPQRRHQit1S 50000.03133700 1P3S1grZYmcqYDuaEDVDYobJ5Fx85E9fE9 50000.03133700 1DEpjpftLbsGiCJvJDp2F2quVRnymV8U5Q 47458.03133700 1BBqjKsYuLEUE9Y5WzdbzCtYzCiQgHqtPN 44914.03133700 1MR6pXDZ6gpBVN8n61SqCNF61vU8ZzRu8Y 44512.03133700 1BVA88962SxcymHSfqXSy9F7cgXefi3zgt 40000.03133700 16Ls6azc76ixc9Ny7AB5ZPPq6oiEL9XwXy 40000.03133700 12HddUDLhRP2F8JjpKYeKaDxxt5wUvx5nq 40000.03133700 1cXNTyXj4xPGopfYZNY5xfSM1EPJJvBZV 38058.03133700 1FngtAcZsLfK89MNe7TqzyqVtSype8TiVD 38000.03133700 18Hsgq92AUB1PYLU6MUMQXiwdebaDRo9oQ 35000.00000000 1DAmsh8tHUtH2cVUDMxnDkKr8SaPNkb36h 31000.03133700 12ib7dApVFvg82TXKycWBNpN8kFyiAN1dr 30000.03133700 1MyGwFAJjVtB5rGJa32M6Yh46cGirUta1K Bitcoin richest 500k BTC ~ USD 50 million stored in a PUBLIC string!
  21. Mining Adding tx records to ledger Confirm transactions Profit (50

    25 BTC / block) ???
  22. None
  23. None
  24. Block chain Broadcasted transaction database since Day 1 (Jan 3

    2009) 1 block every 10 minutes (how?) Currently at >6GB
  25. Block Field Purpose Version Client version Previous hash Hash of

    previous block Merkle root Hash of transactions Timestamp Current UNIX time Target Target hash Nonce 32-bit number
  26. Target 1 block every 10 minutes (this is how!) A

    (max) target hash output Generate lower hash than the target The higher the target is, the harder it is
  27. Target Let’s look back at block’s component and assume that

    we want to make a hash with the following output 0x0000000000000fffffffff.....
  28. Target Difficulty is adjusted every 2016 blocks (2 weeks) Based

    on time it takes for the last 2016 blocks Current chance to find a block: 0.0000000000000000303436847859644281966140511030971538275
  29. Block generation

  30. Block generation

  31. Cryptography is the authority! is the watchdog! Many other clever

    features of Bitcoin
  32. Security incidents

  33. Security incidents

  34. Security incidents

  35. Is Bitcoin safe? https://github.com/bitcoin/bitcoin Reward: USD 140 million

  36. Is Bitcoin safe? https://github.com/bitcoin/bitcoin Reward: USD 140 million Reward: USD

    1.1 billion!
  37. Bitcoin vs Bank Bitcoin Bank Trust no one Trust bank

    Open source Closed source Proven & known security Obscured security
  38. Questions? @uzyn uzyn@zynesis.com