Cryptocurrencies have technological differences in their blockchains, consensus algorithms, and features. Blockchains solve the double spending problem by only allowing one valid transaction when multiple are presented. Bitcoin has faced issues with decentralization due to mining pools and scalability due to its 1MB block size limit. Newer cryptocurrencies implement different consensus algorithms like proof-of-stake to reduce energy use compared to Bitcoin's proof-of-work. Decentralized exchanges allow trading of cryptocurrencies without centralized control through techniques like multisignature transactions. Future cryptocurrencies may achieve better scalability, anonymity, and decentralization through approaches like directed acyclic graphs and masternode-based networks.

1. Cryptocurrencies
Technological differences
By: Hector-Hugo Franco-Penya

2. BTC variants
Technological differences
https://en.wikipedia.org/wiki/Bitcoin#/media/File:Bitcoin_logo.svg
https://www.cuteedge.com/wp-content/uploads/2017/06/btc-savings3-300x300.jpghttp://www.luckybit.eu/s/img/emotionheader.png?1449569116.940px.374px

3. BITCOIN a transaction
TAKE 1.1 from A
SEND 1 to B
Memo: “Non censorable message”
Transaction fee 0.1
Signed by: A

4. Block chain solve double spending
• 2 valid individual transactions
• Send all my credit to A
• Send all my credit to B
• Only 1 transaction can be valid

5. BITCOIN A block
HASH problem solution problem
SOLVED BY A
A get all transaction fee + new credit
LOTS OF
COMPUTERS
trying to mine
= great security

6. Block chain solve double spending
• Two blocks created simultaneously?
• Computing cost to solve problem (proof of work)
Too slow to solve
problems: Aborted
wins

7. Bit torrent file
distribution (ledge)
https://en.wikipedia.org/wiki/BitTorrent
http://www.intertechrecords.com/image/artist/no.government-200.jpg

8. Digital signature
• Algorithm produces 2 keys-
locks.
• What one key encrypts/locks
the other decrypts/unlocks.
• 1 public  to send private
messages to the owner.
• 1 private  to sign
transactions.

9. Multi signature
• Multi-signature account:
• Multiple keys associated to
1 account, a valid
transaction requires some
signatures.
• Enables: DISTRIBUTED
EXCHANGE
https://images-na.ssl-images-amazon.com/images/I/51jrgJ%2BGqqL._SX450_.jpg

10. BTC failure
• Speed
• 1 block / 10 minutes
• Scalability
•  1MB / block
• max transactions
• Decentralization = Mining pools
• Anonymity
http://blogs.harvard.edu/vrm/files/2016/01/BrokenBitcoin.png

11. BTC failure: Decentralization / mining pools
• 5 mining pools take over
50% power
• Hack this 5 = Hack
network. (now 4)
• Most of them in China.
https://blockchain.info/pools

12. Anonymity
• Bitcoin  no names, but traceable.
• Mixing: A and B wants to mix
Take 1 from A
Take 1 from B
Put 1 on C
Put 1 on D
Signed by: A & B
A
B
C
D
https://sobernation.com/wp-content/uploads/2011/10/Anonymity.jpg
Target of crime?

13. https://sobernation.com/wp-content/uploads/2011/10/Anonymity.jpg
Anonymity: Advanced methods
Ring signature
(requires servers)
• DASH
• MONERO* (compulsory)
• BYTECOIN
• FANTOINCOIN
Zero-proof
• Zcoin
• Zcash (also total amount)
• Soon:
• Ethereum
• Pivx (ring  zero)

14. A Persistent Public Billboard: BTC message
• Domain Name DNS:
• NameCoin (NMC) 2011
• Bit-torrent server.
• Emercoin (EMC) 2013
• Vtorrent (VTR) 2014 .
• Social media:
• Self publishing media (new netfilix) : Decent (DCT) 2017
• SMART CONTRACTS:
https://w2.eff.org/images/no_censorship_button.jpg

15. http://etheresante.com/wp-content/uploads/2017/04/photomania-ee67aa4a9e4e9a155be50d86cbea02af.jpg
Smart contracts / scripts
• Over bitcoin: OMNI 2013 do not slow transactions.
• NXT 2013: non-Turing.
• Burst 2014 & Ethereum 2015: Turing, transaction valid if
contract/script is valid. , can slow transactions.
• Byteball 2017 Declarative (like sql) non-Turing (no block-chain)
• NEO 2017
• Enable: DIGITAL Assets: shares, commodities (gold), …

16. Smart contracts / scripts ISSUES
• Slow serves processing transaction
• Omnilayer
• Make contracts expensive, as all nodes have to compute them.
• Lisk
http://etheresante.com/wp-content/uploads/2017/04/photomania-ee67aa4a9e4e9a155be50d86cbea02af.jpg

17. Smart contracts / scripts: Lisk side chains
https://blog.lisk.io/what-is-lisk-and-what-it-isnt-e7b6b6188211
Allow programmers to build their own cryptocurrency chained to lisk, using lisk or their own coin
Issue: requires your own servers, lisk miners do not protect side chains.

18. Treasury & services
• Keep a % of transaction fees to pay developers.
• Less miners  less security & more services
• BitShares (BTS) 2013
• Burstcoin (BUST) 2014
• Einsteinium (EMC2) 2014  philanthropic projects
• Master nodes for ring signatures: Dash 2014.
http://www.chinadaily.com.cn/hkedition/attachement/jpg/site1/20141031/00221917e13e15bd167801.jpg

19. Consensus algorithms
1. Proof-of-work
2. Proof-of-stake
3. Delegate-proof-of-stake
4. Proof-of-Importance
5. Proof-of-Stake-Velocity
6. Utilizing the Computational Power
7. Trading Computer Power
8. Proof-of-Capacity
9. Private Networks
10. On Reducing Electricity
problem solution
SOLVED BY A

20. Consensus: Proof-of-work
• Bitcoin
• 1 transaction = 2.7 days house hold power America.
• Specialized hardware & cheap electricity.
• Litecoin (LTC)
• No hardware advantage.
http://laoblogger.com/images/mining-clipart-black-and-white-2.jpg

21. Consensus: Proof-of-stake : In greed we trust
• More capital = more likely to make next block.
• Issue: miners, both forks, for free. (Ethereum POW)
• Solution: Collateral
• Examples:
• Peercoin (PPC) 2012,
• NXT (NXT) 2013,
• Blackcoin (BLK) 2014
http://boxmining.com/wp-content/uploads/2017/05/proof-of-work-vs-proof-of-stake.jpg

22. Consensus: Delegated-proof-of-stake
• Users choose to delegate the power to create a new node.
• BitShares 2013 first
• Lisk (LSK) 2016.
•  VERY FAST!

23. Consensus: Proof-of-Importance
“Consuming is good”
• Nem (XEM) 2015, number of transactions
made from their wallet, aiming to promote
nodes to carry out transactions. The more
transactions the more healthy economy.
http://buysellgraphic.com/images/graphic_preview/large/money_circle_24761.jpg

24. Consensus: Proof-of-Stake-Velocity
• Reddcoin (RDD) rewarding computers
sharing the file-block-chain.
 facilitates users to incorporate new
nodes to the network.
https://en.wikipedia.org/wiki/BitTorrent

25. Consensus: POW + useful work
• Find PRIME numbers (good for cryptography)
• Primecoin (XPM) 2013
• Riecoin (RIC) 2014 (better test)

26. Consensus: Trading computation
• Gridcoin 2013:  rewards donors with coin. No consensus.
• MaidSafeCoin (MAID) (? On development) Trade computer resources,
not only to maintain the cryptocurrency but also as service.

27. Consensus: Proof-of-capacity
• Algorithm requires Hard disk.
• Burstcoin (BUST) 2014
• Fairer distribution
• Low electricity

28. • Increasingly more decentralize
BITCOIN

29. Consensus: Private networks
• Private company maintains the network.
• No need for miners
• No need to verify problems.
• No reward for building a block.
• Ripple (XRP) 2012
• Stellar Lumens (XLM) 2014

30. Consensus: On Reducing Electricity
•The best solution
- reward  - miners
Is a million miners > than a thousand?
•“VIRES IN NUMERIS”?
https://www.citi.io/wp-content/uploads/2015/02/344-7.jpg

31. https://www.cuteedge.com/wp-content/uploads/2017/06/btc-savings3-300x300.jpg
Block chain free cryptocurrencies

32. DAG: Direct Acyclic Graph:
http://cryptowiki.net/index.php?title=Blockchain-free_cryptocurrencies
• Link transaction to previous
• Transactions can be linked if both
valid (double spending)
• Scalable

33. DAG: Direct Acyclic Graph:
http://cryptowiki.net/index.php?title=Blockchain-free_cryptocurrencies
• Yellow transaction is valid if all red transactions are valid
• No blocks
• No new credit
• No miners
• No pools  BTC security problem
• Smart contracts – declarative – non-Turing
Examples:
• IOTA 2016
• Byteball / Blackball 2017
(anonymous transactions)

34. SAFE: Secure Access For Everyone 201?
• Provides servers = can replace the whole INTERNET.
• Messaging, apps, email, social networks, data storage and video
conferencing.
• Attack requires 75% of nodes.
• Truly exchange/mine hard disk and bandwidth for coin. (unlike
gridcoin)
Coin value Current owner Previous owner
10 A B
10 A B
5 A B
1 B C
No ledge 
synchronized table of
coins and owners.

35. Exchange markets
https://ak2.picdn.net/shutterstock/videos/1299583/thumb/11.jpg
https://www.cuteedge.com/wp-content/uploads/2017/06/btc-savings3-300x300.jpg

36. Exchange Markets
Centralized
• Give me the assets and I will
exchange them. Like a bank
• Most are centralized Take 0.25%
• 2010-2014 security
De-centralized
• Internal assets
• External assets
• Fiat (Dollar, Euro…)

37. Decentralized internal assets exchange
• E.g.
• Exchange internal Ethereum assets, operates inside Ethereum.
• Takes 0.25%
https://etherboost.github.io/images/etherdelta_logo.svg

38. Decentralized external
• E.g. Open ledger
• Multi signatures  BTC, Ether, etc becomes internal token.
• Several servers have to sign a transaction to take currency out of the
exchange wallet.
https://cointelegraph.com/storage/uploads/view/bb768539b6b5c78bc358b0ee1721054e.png

39. Decentralized external & internal
• E.g. & open ledger
• BitShares provides a block chain for storing transactions .
• Non-Turing contracts. Optimize for building an exchange.
• Design exchange: (Unlike Ethereum)
• Could handle NASDAQ traffic
• Orders processed in a second. (delegate proof of stake)
• Basic token: Dollar & Euro (price stability) & BTC (send btc for >1c to BitShares account)
• Allows recurrent payments (like a bank)
https://cointelegraph.com/storage/uploads/view/bb768539b6b5c78bc358b0ee1721054e.png

40. Decentralized external & internal
• E.g. & open ledger
• Also has internal tokens (like Ethereum).
• Nicknames for accounts.
• Free exchange:
• No % taken for exchange.
• Free is the cost of placing order in the block chain (less than 1cent)
• Cheap & secure.
• BitShares 2013 also NXT 2013
https://cointelegraph.com/storage/uploads/view/bb768539b6b5c78bc358b0ee1721054e.png

41. Decentralized Fiat exchange
• Collateral to block online.
• Arbitrator
• Bank transfer peer to peer

42. Future of a single world decent currency
Scalability Anonymity Speed Decentralized Tokens Other
Bitcoin Block limit Low Low (SegWit)
10min/block
Mining pools Omni layer
Ethereum Not
optimized for
ICOs
in dev Good
13-17s/block
Mining pools Yes
BitShares Nasdaq traffic in dev 0.7s/block,
~cards
?? Yes Free
exchange
market
Byteball No block
chain
blackballs ? completely Yes
SAFE ? ? ? Yes Virtual
servers

43. Further details Thanks for your attention