21 BTCAdam Back
Adam Back: Inventor of Hashcash, cited in the Bitcoin whitepaper; co-founder and CEO of Blockstream. Cypherpunk and cryptographer. In 1997 he proposed Hashcash, the proof-of-work that Bitcoin mining uses. In 2008 Satoshi emailed him before publishing the whitepaper, and he pointed Satoshi to Wei Dai's b-money. In 2024 he testified in COPA v Wright.
Background
- University of Exeter, PhD in computer science (distributed systems)
- Blockstream, co-founder (2014) and CEO
- Zero-Knowledge Systems (privacy technology, with Austin Hill)
- “ecash, privacy tech, crypto, distributed systems” (his words, 2013)
Connections
- Satoshi Nakamoto: Satoshi emailed him on 20 Aug 2008; he replied on 21 Aug and pointed to b-money
- Wei Dai: Pointed Satoshi to Wei Dai's b-money, which became reference [1]
- Gregory Maxwell: Blockstream co-founders (2014)
- Pieter Wuille: Blockstream co-founders (2014)
In their own words
“Heres a bit of perl code which implements RSA encryption and decryption and is small enough to use for a signature” (9 Mar 1995, via cypherpunks mailing list)
“The idea of using partial hashes is that they can be made arbitrarily expensive to compute (by choosing the desired number of bits of collision), and yet can be verified instantly.” (28 Mar 1997, via cypherpunks mailing list)
“Hashcash is free, all you've got to do is burn some cycles on your PC.” (28 Mar 1997, via cypherpunks mailing list)
“The hashcash CPU cost-function computes a token which can be used as a proof-of-work.” (1 Aug 2002, via paper)
See also
- Satoshi NakamotoSatoshi Nakamoto: Creator of Bitcoin (pseudonym), active 2008–2011. Wrote the Bitcoin whitepaper (31 Oct 2008), mined the genesis block and released Bitcoin v0.1 (8 Jan 2009). Handed the project to other developers in December 2010 and stopped writing in April 2011.
- Wei DaiWei Dai: Computer engineer, author of b-money, reference [1] of the whitepaper. Described b-money in 1998: money created by solving computational problems and kept on pseudonymous accounts. Satoshi wrote that Bitcoin “expands on your ideas into a complete working system”.
- Gregory MaxwellGregory Maxwell: Early Bitcoin developer; proposed CoinJoin (2013); co-founder of Blockstream (2014). In June 2011 he argued on the forum that Bitcoin should default to deterministic wallets; BIP32 later credits him with “the original idea of type-2 deterministic wallets”. In August 2013 he proposed CoinJoin for on-chain privacy. Blockstream's 2014 seed-round post lists him among its co-founders.
- Pieter WuillePieter Wuille: Bitcoin Core developer; author of BIP32 and co-author of SegWit, Schnorr and Taproot; Blockstream co-founder; now at Chaincode Labs. Author of BIP32, the hierarchical deterministic wallets behind today's seed phrases, and co-author of BIP141 (SegWit), BIP340 (Schnorr signatures) and BIP341 (Taproot). He proposed Taproot on the bitcoin-dev list on 6 May 2019; it activated at block 709,632 in November 2021. Blockstream's 2014 post lists him among its co-founders; his website says he now does Bitcoin research and development at Chaincode Labs.
References
- X · @adam3us x.com
- cypherspace.org/adam cypherspace.org
- hashcash.org hashcash.org
- GitHub · adam3us github.com
- bitcoindefense.org bitcoindefense.org
- cypherspace.org cypherspace.org
- hashcash.org hashcash.org
- hashcash.org hashcash.org
- gwern.net gwern.net
- blog.blockstream.com blog.blockstream.com