Cryptography: How is Bitcoin safer than your bank

Cae2dd246ed83dd458e4ce5f927aa2f7?s=47 U-Zyn Chua
August 18, 2012

Cryptography: How is Bitcoin safer than your bank

Keynote at GeekCamp Singapore 2012 (http://geekcamp.sg/schedule/view_schedule/2012)

Fiat currencies and Bitcoin are valuable, despite being physically intangible, unlike gold is. However, while fiat currencies rely on government regulations to maintain their values and security, Bitcoin requires none of the authority interventions or appointed watchdogs, all thanks to cryptography.

This talk covers basic and intermediate topics on how cryptology aids in the working of Bitcoin P2P network.

Cae2dd246ed83dd458e4ce5f927aa2f7?s=128

U-Zyn Chua

August 18, 2012
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Transcript

  1. 5.
  2. 7.

    What is Bitcoin? Satoshi Nakamoto Genesis block on 3 Jan

    2009 “Gone for good” since late 2010
  3. 15.

    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.
  4. 18.

    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
  5. 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 500k BTC ~ USD 7.5 million stored in a PUBLIC string!
  6. 21.
  7. 22.
  8. 23.

    Block chain Broadcasted transaction database since Day 1 (Jan 3

    2009) 1 block every 10 minutes (how?) Currently at 2.1GB
  9. 24.

    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
  10. 25.

    Target 1 block every 10 minutes (this is how!) A

    (max) target hash output Generate lower hash than the target The lower the target is, the harder it is
  11. 26.

    Target Let’s look back at block’s component and assume that

    we want to make a hash with the following target 0x0000000000000fffffffff.....
  12. 27.

    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: 0.0000000000000001062717181778399105906984800640202593058
  13. 34.

    Bitcoin vs Bank Bitcoin Bank Trust no one Trust bank

    Open source Closed source Proven & known security Unknown & obscured security Can’t phish Prone to phish