slides-04-berner-js.md

Bitcoin Cryptography with JavaScript

Oliver Gugger

Full Stack Engineer at Puzzle ITC
github.com/guggero
@gugol
slides: https://gugger.guru

ECC block asymmetric address private key SHA256 signature merkle tree ECDSA public key transaction HMAC multi-signature RIPEMD160

Don't worry! This is a high-level overview for engineers and coders.

Cryptography Primitives in Bitcoin

• Elliptic curves (ECC / ECDSA)
• Hashing (SHA, RIPEMD)

Elliptic Curve Cryptography

• Geometry based one-way function
• Can be used for key exchange (ECDH) and signatures (ECDSA)
• Shorter key size compared to RSA
  (256bit ECC ≃ 3072bit RSA)

Cryptographic Hashing

• Collision resistant, constant-size fingerprint
• SHA256 extensively used in Bitcoin
• RIPEMD160 as a secondary safety net for addresses

Demo: Libraries used

Demo

• Web Crypto API (browser)
• bitcoinjs-lib (github.com/bitcoinjs/bitcoinjs-lib)

Security concerns

• 2²⁵⁶ ≃ 10⁷⁷ addresses
  (universe has ~10⁸⁰ atoms)
• Bitcoin Mining: ~76bit in 10 minutes
• Use secure "randomness"
• Be very careful with browser RNGs!

Further topics

• Hierarchical Deterministic (HD) wallets
• Merkle Trees
• HMAC
• PBKDF2

Thank you!

Questions?