Alternatives to Blockchains Sarah Meiklejohn (University College London)
fully decentralized cryptocurrencies 2
fully decentralized cryptocurrencies tx tx(addr A → addr B ) 2
fully decentralized cryptocurrencies tx “mining” tx(addr A → addr B ) (generate transaction ledger) (generate monetary supply) 2
fully decentralized cryptocurrencies tx “mining” tx(addr A → addr B ) (generate transaction ledger) (generate monetary supply) append-only transparent pseudonyms 2
issues with Bitcoin lack of fungibility 3
issues with Bitcoin lack of fungibility hashing rates are out of control 4
1.5 EH/s (1.5 x 10 18 H/s)! 5
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability 6
1.5 EH/s (1.5 x 10 18 H/s) to achieve 7 tx/s! 7
70GB and no end in sight! 8
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability lack of consumer protection 9
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability lack of consumer protection attacks on mining / misaligned incentives 10
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability lack of consumer protection attacks on mining / misaligned incentives 11
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability lack of consumer protection attacks on mining / misaligned incentives 11
alternate storage Lightning Network truncate after a certain amount of time? 12
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability lack of consumer protection attacks on mining / misaligned incentives 13
alternate proof of … 14
proof of stake use of computational resources represents stake in system other forms of stake? (icon by lastspark for the noun project) 15
proof of stake use of computational resources represents stake in system other forms of stake? old coins tx “proof of burn” “proof of coin age” (icon by lastspark for the noun project) 15
proof of stake use of computational resources represents stake in system other forms of stake? old coins tx “proof of burn” “proof of coin age” tx tx tx tx “proof of use” coins coins coins coins (icon by lastspark for the noun project) 15
proof of stake use of computational resources represents stake in system other forms of stake? old coins tx “proof of burn” “proof of coin age” tx tx tx tx “proof of use” coins coins coins coins tx tx “security-deposit PoS” <time-lock coins> <vote on blocks> (icon by lastspark for the noun project) 15
proof of stake use of computational resources represents stake in system other forms of stake? old coins tx “proof of burn” “proof of coin age” tx tx tx tx “proof of use” coins coins coins coins tx tx “security-deposit PoS” <time-lock coins> <vote on blocks> are these secure ? how can we tell? (icon by lastspark for the noun project) 15
proof of stake (icon by lastspark for the noun project) 16
proof of stake ? (icon by lastspark for the noun project) 16
proof of stake ? in proof-of-work, cost means you choose (icon by lastspark for the noun project) 16
proof of stake in proof-of-work, cost means you choose (icon by lastspark for the noun project) 16
proof of stake in proof-of-work, cost means you choose (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment how do miners get chosen? in proof-of-work, can’t influence this decision (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment how do miners get chosen? in proof-of-work, can’t influence this decision (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment how do miners get chosen? in proof-of-work, can’t influence this decision (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment how do miners get chosen? in proof-of-work, can’t influence this decision (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment how do miners get chosen? in proof-of-work, can’t influence this decision (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment “stake grinding” how do miners get chosen? in proof-of-work, can’t influence this decision (icon by lastspark for the noun project) 16
proof of stake “nothing at stake” in proof-of-work, cost means you choose in proof-of-stake, address with punishment “stake grinding” how do miners get chosen? in proof-of-work, can’t influence this decision in proof-of-stake, address with stake modifiers (icon by lastspark for the noun project) 16
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability lack of consumer protection attacks on mining / misaligned incentives 17
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability lack of consumer protection attacks on mining / misaligned incentives not suitable for many applications! 17
issues with Bitcoin lack of fungibility hashing rates are out of control lack of scalability lack of consumer protection attacks on mining / misaligned incentives not suitable for many applications! 18
RSCoin [D M NDSS’16] RSCoin monetary supply decentral central central ledger decentral distribute central transparent? y y n pseudonyms? y y n computation high! low low 19
user (generate transaction ledger) mintette mintette mintette mintette (generate monetary supply) bank 20
user mintette mintette mintette mintette bank 21
user mintette mintette mintette mintette who are the mintettes? who are the mintettes? bank (anyone bank authorizes) 21
how do mintettes user collect txs? mintette mintette mintette mintette who are the mintettes? bank (anyone bank authorizes) 21
how do mintettes user collect txs? (chained transactions) lower-level blocks lower-level blocks mintette mintette mintette mintette who are the mintettes? bank (anyone bank authorizes) 21
how do mintettes user collect txs? (chained transactions) lower-level blocks mintette mintette mintette mintette consensus? who are the mintettes? bank (anyone bank authorizes) 21
how do mintettes user collect txs? (chained transactions) lower-level blocks mintette mintette mintette mintette consensus? who are the mintettes? bank (anyone bank authorizes) higher-level blocks higher-level blocks (transactions + coingen + authorization) 21
how do mintettes user collect txs? (chained transactions) lower-level blocks mintette mintette mintette mintette consensus? consensus? who are the mintettes? bank (anyone bank authorizes) higher-level blocks (transactions + coingen + authorization) 21
consensus 4 service tx 1 mintette 2 1 mintette 1 ✓ 2 2 mintette 2 user mintette 1 ✓ ✓ 1 tx tx 3 tx: 1 2 ✓ mintette 2 mintette 1 simple adaptation of Two-Phase Commit (2PC) 22
service 1 1 2 user tx: 1 2 23
service 1 1 2 user tx: 1 2 t r a n s a c t i o n s 23
service 1 1 2 user tx: 1 2 t r a n s a c t i o n s 23
service 1 1 2 user tx: 1 2 mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette t r a n s a c t i o n s 23
service 1 1 1 : mintette mintette mintette 2 user tx: 1 2 mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette mintette t r a n s a c t i o n s 23
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