1. Cryptocurrency
Mixing
Privacy implementations with
JoinMarket for Bitcoin
and
Masternode mixing for Dash

2. Contents
A normal transaction
What is the problem for privacy?
How does CoinJoin help?
JoinMarket: peer-to-peer CoinJoin for Bitcoin
Masternode mixing: ahead-of-time mixing for
Dash
Summary

3. Transactions

4. Example transactions
10 BTC 7 BTC
3 BTC
signature
input output
output
3 BTC 4 BTC
1 BTC
signature
input output
output
2 BTC
signature
input

5. Example real
transaction
signature
public key

6. Typical “send money”
case
10 BTC 7 BTC
3 BTC
signature
change returned to sender
money drawn
from wallet
money sent
to recipient
What does Bob know
about Alice’s finances?

7. Multiple inputs
a: 6 BTC 7 BTC
3 BTC
signature
change returned to sender
money drawn
from wallet
money sent
to recipient
b: 4 BTC
signature
How much extra information
does this reveal to Bob?

8. Address reuse
10 BTC 7 BTC
3 BTC
signature
3 BTC 4 BTC
1 BTC
signature
1abcxyz…
What does this reveal about Alice and Dorothy?
3 BTC
signature

9. CoinJoin

10. Disjunct transactions
10 BTC 7 BTC
3 BTC
signature
input output
output
3 BTC 4 BTC
1 BTC
signature
input output
output
2 BTC
signature
Even they are made by different people,
do they need to be separate on the blockchain?

11. Joined transactions
10 BTC 7 BTC
3 BTC
signature
input output
output
3 BTC 4 BTC
1 BTC
signature
input output
output
2 BTC
signature
input
Is it possible to correlate the inputs with the outputs?

12. JoinMarket

13. JoinMarket actors
Investor with
spare bitcoins and time
Bitcoin user who wants
extra privacy
“taker”“maker”

14. JoinMarket principle
Ivan the Investor
How do we get people like Ivan to
keep his coins in a wallet for mixing?
taker fee

15. Network topology
IRC server
(trading pit)
Tor network
mixing peer mixing peermixing peer
(future versions of
JoinMarket may replace
IRC with P2P
communication)

16. CoinJoin
communication
maker
taker
maker
running
yieldgenerator.py
running
yieldgenerator.py
private messages
running
sendpayment.py
public messages
order
orderbook
orderbookfill
pubkey
ioauth
auth
tx
sig
(etc…)

17. Sample Transaction
3 parties, amount 25 BTC

18. How does it look?

19. Installation
% git clone
https://github.com/JoinMarket-Org/joinmarket.git
joinmarket-btcmcr1
% cd joinmarket-btcmcr1

20. Wallet generation
% python wallet-tool.py generate
2016-05-01 18:50:04,176 [MainThread ] [DEBUG] hello joinmarket
Write down this wallet recovery seed
warm shade knee satisfy child bone hug door leaf depress blur use
Enter wallet encryption passphrase:
Reenter wallet encryption passphrase:
Input wallet file name (default: wallet.json):
saved to wallet.json
generate command
wallet seed
wallet filename

21. Switch to
Bitcoin full node
see local Bitcoin Core/Classic etc data folde

22. Switch to
Bitcoin full node
display wallet
command
% python wallet-tool.py wallet.json
2016-05-01 18:58:49,303 [MainThread ] [DEBUG] hello joinmarket
Enter wallet decryption passphrase:
2016-05-01 18:58:50,722 [MainThread ] [DEBUG] requesting wallet history
2016-05-01 18:58:54,491 [MainThread ] [DEBUG] rpc: getaddressesbyaccount
['joinmarket-wallet-9e5123']
2016-05-01 18:58:54,496 [MainThread ] [DEBUG] importing 200 addresses
into account joinmarket-wallet-9e5123
restart Bitcoin Core with -rescan if you're recovering an existing wallet from backup
seed
otherwise just restart this joinmarket script
importing into a local watch-only wallet
local Bitcoin node has only public keys, not private keys)

23. Show wallet contents
display wallet command
% python wallet-tool.py wallet.json
2016-05-01 19:23:41,613 [MainThread ] [DEBUG] hello joinmarket
Enter wallet decryption passphrase:
2016-05-01 19:23:43,774 [MainThread ] [DEBUG] requesting wallet history
2016-05-01 19:23:47,478 [MainThread ] [DEBUG] rpc: getaddressesbyaccount ['joinmarket-wallet-9e5123']
2016-05-01 19:23:47,484 [MainThread ] [DEBUG] rpc: listtransactions ['joinmarket-wallet-9e5123', 1000, 0,
True]
2016-05-01 19:23:51,193 [MainThread ] [DEBUG] rpc: listunspent [0]
2016-05-01 19:23:51,200 [MainThread ] [DEBUG] bitcoind sync_unspent took 0.00770592689514sec
mixing depth 0 m/0/0/
external addresses m/0/0/0/
m/0/0/0/000 14hzgMvxf9GhPTWjBxA7MHd8ytGT9dsp7n new 0.00000000 btc
m/0/0/0/001 14QNhbnkBC6HQJgfgBP2hRDo57Ct7pKNMa new 0.00000000 btc
m/0/0/0/002 1AgtMNiGVHS6oVisDbQT8VVhv9xC31QeUa new 0.00000000 btc
m/0/0/0/003 12wtzHevXDxzi5eUqYja4cFCT9CA7msqDL new 0.00000000 btc
m/0/0/0/004 1HPzdoUDVXyPs2Awr4VFGncvc8qL3pF5jv new 0.00000000 btc
m/0/0/0/005 1KVr1QjiUsTPCyQhaGNth8BZwYaBydPTpp new 0.00000000 btc
internal addresses m/0/0/1/
for mixdepth=0 balance=0.00000000btc
mixing depth 1 m/0/1/
external addresses m/0/1/0/
m/0/1/0/000 19UBkuXV3kUFwdjkUyW6btL76NQSHNxoKP new 0.00000000 btc
m/0/1/0/001 17bSF43rrcK6stgAXbbEEwBQJMSMh2pMhX new 0.00000000 btc
…
1st internal
wallet
2st internal
wallet, etc

24. Fund wallet (anyhow)
output sent to JoinMarket wallet

25. % python wallet-tool.py wallet.json
2016-05-01 19:52:16,028 [MainThread ] [DEBUG] hello joinmarket
…
mixing depth 0 m/0/0/
external addresses m/0/0/0/
m/0/0/0/000 14hzgMvxf9GhPTWjBxA7MHd8ytGT9dsp7n used 0.10000000 btc
m/0/0/0/001 14QNhbnkBC6HQJgfgBP2hRDo57Ct7pKNMa new 0.00000000 btc
m/0/0/0/002 1AgtMNiGVHS6oVisDbQT8VVhv9xC31QeUa new 0.00000000 btc
m/0/0/0/003 12wtzHevXDxzi5eUqYja4cFCT9CA7msqDL new 0.00000000 btc
m/0/0/0/004 1HPzdoUDVXyPs2Awr4VFGncvc8qL3pF5jv new 0.00000000 btc
m/0/0/0/005 1KVr1QjiUsTPCyQhaGNth8BZwYaBydPTpp new 0.00000000 btc
m/0/0/0/006 184EYAbYveTYYLNW1ewTFV4ysEqpAswvN4 new 0.00000000 btc
internal addresses m/0/0/1/
for mixdepth=0 balance=0.10000000btc
mixing depth 1 m/0/1/
external addresses m/0/1/0/
m/0/1/0/000 19UBkuXV3kUFwdjkUyW6btL76NQSHNxoKP new 0.00000000 btc
m/0/1/0/001 17bSF43rrcK6stgAXbbEEwBQJMSMh2pMhX new 0.00000000 btc
Check funds received
1st internal
wallet

26. % python sendpayment.py wallet.json -N 5 -m 0 2500000 19UBkuXV3kUFwdjkUyW6btL76NQSHNxoKP
2016-05-01 22:41:48,340 [MainThread ] [DEBUG] hello joinmarket
Generated random nickname: Supixaxal
2016-05-01 22:41:48,415 [MainThread ] [DEBUG] starting sendpayment
Enter wallet decryption passphrase:
2016-05-01 22:41:52,519 [MainThread ] [DEBUG] requesting wallet history
2016-05-01 22:41:53,273 [MainThread ] [DEBUG] rpc: getaddressesbyaccount ['joinmarket-wallet-9e5123']
2016-05-01 22:41:53,279 [MainThread ] [DEBUG] rpc: listtransactions ['joinmarket-wallet-9e5123', 1000, 0,
True]
2016-05-01 22:41:54,070 [MainThread ] [DEBUG] rpc: listunspent []
2016-05-01 22:41:54,078 [MainThread ] [DEBUG] bitcoind sync_unspent took 0.00794100761414sec
2016-05-01 22:41:54,083 [MainThread ] [DEBUG] starting irc
2016-05-01 22:41:54,083 [Thread-1 ] [DEBUG] starting ping thread
2016-05-01 22:41:54,084 [Thread-2 ] [DEBUG] starting throttle thread
2016-05-01 22:41:54,084 [MainThread ] [DEBUG] connecting
2016-05-01 22:41:57,173 [MainThread ] [DEBUG] Connected to IRC and joined channel
2016-05-01 22:41:57,174 [MainThread ] [DEBUG] >>pubmsg !orderbook
waiting for all orders to certainly arrive
…
2016-05-01 22:42:50,535 [MainThread ] [DEBUG] created fully signed tx, ending
2016-05-01 22:42:50,574 [MainThread ] [DEBUG] line was zero length
2016-05-01 22:42:50,575 [MainThread ] [DEBUG] disconnected irc
2016-05-01 22:42:50,575 [MainThread ] [DEBUG] ending irc
Send funds
send payment
command
join the
market
broadcast

27. Check join

28. % python wallet-tool.py wallet.json
2016-05-01 22:50:20,154 [MainThread ] [DEBUG] hello joinmarket
Enter wallet decryption passphrase:
2016-05-01 22:50:22,238 [MainThread ] [DEBUG] requesting wallet history
2016-05-01 22:50:26,245 [MainThread ] [DEBUG] rpc: getaddressesbyaccount ['joinmarket-wallet-9e5123']
2016-05-01 22:50:26,251 [MainThread ] [DEBUG] rpc: listtransactions ['joinmarket-wallet-9e5123', 1000, 0,
True]
2016-05-01 22:50:30,130 [MainThread ] [DEBUG] rpc: listunspent [0]
2016-05-01 22:50:30,137 [MainThread ] [DEBUG] bitcoind sync_unspent took 0.00749111175537sec
mixing depth 0 m/0/0/
external addresses m/0/0/0/
m/0/0/0/001 14QNhbnkBC6HQJgfgBP2hRDo57Ct7pKNMa new 0.00000000 btc
m/0/0/0/002 1AgtMNiGVHS6oVisDbQT8VVhv9xC31QeUa new 0.00000000 btc
m/0/0/0/003 12wtzHevXDxzi5eUqYja4cFCT9CA7msqDL new 0.00000000 btc
m/0/0/0/004 1HPzdoUDVXyPs2Awr4VFGncvc8qL3pF5jv new 0.00000000 btc
m/0/0/0/005 1KVr1QjiUsTPCyQhaGNth8BZwYaBydPTpp new 0.00000000 btc
m/0/0/0/006 184EYAbYveTYYLNW1ewTFV4ysEqpAswvN4 new 0.00000000 btc
internal addresses m/0/0/1/
m/0/0/1/000 19DZ1jXweJtmBNn7UUPdJU2G2A8cuDCQ5y used 0.07448981 btc
for mixdepth=0 balance=0.07448981btc
mixing depth 1 m/0/1/
external addresses m/0/1/0/
m/0/1/0/000 19UBkuXV3kUFwdjkUyW6btL76NQSHNxoKP used 0.02500000 btc
m/0/1/0/001 17bSF43rrcK6stgAXbbEEwBQJMSMh2pMhX new 0.00000000 btc
Compare mixing
depths
1st internal
wallet
2nd internal
wallet

29. % python sendpayment.py wallet.json -N 5 -m 1 0 14QNhbnkBC6HQJgfgBP2hRDo57Ct7pKNMa
2016-05-01 22:54:38,682 [MainThread ] [DEBUG] hello joinmarket
Generated random nickname: Moxivexoh
2016-05-01 22:54:38,759 [MainThread ] [DEBUG] starting sendpayment
…
% python wallet-tool.py wallet.json
…
mixing depth 0 m/0/0/
external addresses m/0/0/0/
m/0/0/0/001 14QNhbnkBC6HQJgfgBP2hRDo57Ct7pKNMa used 0.02411938 btc
m/0/0/0/002 1AgtMNiGVHS6oVisDbQT8VVhv9xC31QeUa new 0.00000000 btc
m/0/0/0/003 12wtzHevXDxzi5eUqYja4cFCT9CA7msqDL new 0.00000000 btc
m/0/0/0/004 1HPzdoUDVXyPs2Awr4VFGncvc8qL3pF5jv new 0.00000000 btc
m/0/0/0/005 1KVr1QjiUsTPCyQhaGNth8BZwYaBydPTpp new 0.00000000 btc
m/0/0/0/006 184EYAbYveTYYLNW1ewTFV4ysEqpAswvN4 new 0.00000000 btc
m/0/0/0/007 14jmzkDjF2Ruyn3kQwYsaS2quorjyqsZ72 new 0.00000000 btc
internal addresses m/0/0/1/
m/0/0/1/000 19DZ1jXweJtmBNn7UUPdJU2G2A8cuDCQ5y used 0.07448981 btc
for mixdepth=0 balance=0.09860919btc
mixing depth 1 m/0/1/
external addresses m/0/1/0/
m/0/1/0/001 17bSF43rrcK6stgAXbbEEwBQJMSMh2pMhX new 0.00000000 btc
m/0/1/0/002 1Hi5j3iyjUmGstQq5tLYjMTKNoVvZ5czCB new 0.00000000 btc
m/0/1/0/003 19VZdjKBPXTzcWqsfLpjzPs1do1KWcPncK new 0.00000000 btc
m/0/1/0/004 1FFRrzqMZbdDxdX75p7UrjY9crLi1bzGEb new 0.00000000 btc
m/0/1/0/005 1BSJ5Y77hBwRwKSwZXKnDBWZF3WikC3PNo new 0.00000000 btc
m/0/1/0/006 18x4KsBcUQnrGccVHvHWSRb8gco8nKUyja new 0.00000000 btc
internal addresses m/0/1/1/
for mixdepth=1 balance=0.00000000btc
Empty a mixing depth
amount = 0
new total
balance

30. Tumbling

31. Generate receive
addresses
generate multiple addresses for enhanced privacy

32. % python wallet-tool.py wallet.json
2016-05-02 16:16:38,556 [MainThread ] [DEBUG] hello joinmarket
Enter wallet decryption passphrase:
…
mixing depth 0 m/0/0/
external addresses m/0/0/0/
m/0/0/0/001 14QNhbnkBC6HQJgfgBP2hRDo57Ct7pKNMa used 0.02411938 btc
m/0/0/0/002 1AgtMNiGVHS6oVisDbQT8VVhv9xC31QeUa used 0.05054509 btc
m/0/0/0/003 12wtzHevXDxzi5eUqYja4cFCT9CA7msqDL new 0.00000000 btc
m/0/0/0/004 1HPzdoUDVXyPs2Awr4VFGncvc8qL3pF5jv new 0.00000000 btc
m/0/0/0/005 1KVr1QjiUsTPCyQhaGNth8BZwYaBydPTpp new 0.00000000 btc
m/0/0/0/006 184EYAbYveTYYLNW1ewTFV4ysEqpAswvN4 new 0.00000000 btc
m/0/0/0/007 14jmzkDjF2Ruyn3kQwYsaS2quorjyqsZ72 new 0.00000000 btc
m/0/0/0/008 1XDsccCJLDGsW9VvzaFT2kjS332wJnqwr new 0.00000000 btc
internal addresses m/0/0/1/
m/0/0/1/001 1P1ZXH2KZWBnWmfxepbf4rVtui9ZYBYgE used 0.02309129 btc
for mixdepth=0 balance=0.09775576btc
Check mixing depth 0
Coins I
prepared
earlier
We will be tumbling
this much

33. % python tumbler.py wallet.json --timelambda=1 13hGdJFTFaSaD8eJ4rXQ2yL12gVEa7LHZM
1Ck161xjSdDHwdauh7BA9ePRtx3VVzdpVg 1GEn4mdF77EULNLzoE27Eo6mpwmr8xGNEn
2016-05-02 16:20:24,266 [MainThread ] [DEBUG] hello joinmarket
['13hGdJFTFaSaD8eJ4rXQ2yL12gVEa7LHZM', '1Ck161xjSdDHwdauh7BA9ePRtx3VVzdpVg',
'1GEn4mdF77EULNLzoE27Eo6mpwmr8xGNEn']
{'liquiditywait': 60, 'addrcount': 3, 'minmakercount': 2, 'amountpower': 100.0, 'txcountparams': (4, 1),
'mixdepthcount': 4, 'waittime': 20, 'txfee': 5000, 'mincjamount': 100000, 'mixdepthsrc': 0, 'makercountrange': (3,
1.5), 'maxcjfee': (0.01, 10000), 'donateamount': 0, 'timelambda': 1.0, 'mintxcount': 1}
2016-05-02 16:20:24,305 [MainThread ] [DEBUG] tumbler transaction list
…
TBC
Start tumble
tumble command
option to use average wait time
of 1 minute instead of 30
outputs

34. 2016-05-02 16:20:24,305 [MainThread ] [DEBUG] tumbler transaction list
[{'srcmixdepth': 0,
'tx': [{'amount_fraction': 0.26377219630602206,
'destination': 'internal',
'makercount': 2,
'wait': 0.77},
{'amount_fraction': 0.736227803693978,
'destination': 'internal',
'makercount': 2,
'wait': 0.04}]},
{'srcmixdepth': 1,
'tx': [{'amount_fraction': 0.12876737962157553,
'destination': 'internal',
'makercount': 2,
'wait': 2.36},
{'amount_fraction': 0.10885260611117395,
'destination': 'internal',
'makercount': 2,
'wait': 3.95},
{'amount_fraction': 0.7623800142672505,
'destination': '1GEn4mdF77EULNLzoE27Eo6mpwmr8xGNEn',
'makercount': 2,
'wait': 0.16}]},
{'srcmixdepth': 2,
'tx': [{'amount_fraction': 0.5982821353871555,
'destination': 'internal',
'makercount': 2,
'wait': 0.28},
{'amount_fraction': 0.40171786461284453,
'destination': '1Ck161xjSdDHwdauh7BA9ePRtx3VVzdpVg',
'makercount': 2,
'wait': 0.89}]},
{'srcmixdepth': 3,
'tx': [{'amount_fraction': 1.0,
'destination': '13hGdJFTFaSaD8eJ4rXQ2yL12gVEa7LHZM',
'makercount': 3,
'wait': 0.18}]}]
waits in total for 8 blocks and 8.63 minutes
estimated time taken 88.63 minutes or 1.48 hours
tumble with these tx? (y/n):y
…
split of funds into
next round
outputs

35. Collect coins
technical error:
tumbling stalled before I could finish the presentation
% python wallet-tool.py wallet.json
…
mixing depth 0 m/0/0/
external addresses m/0/0/0/
m/0/0/0/001 14QNhbnkBC6HQJgfgBP2hRDo57Ct7pKNMa used 0.02411938 btc
m/0/0/0/002 1AgtMNiGVHS6oVisDbQT8VVhv9xC31QeUa used 0.05054509 btc
m/0/0/0/003 12wtzHevXDxzi5eUqYja4cFCT9CA7msqDL new 0.00000000 btc
m/0/0/0/004 1HPzdoUDVXyPs2Awr4VFGncvc8qL3pF5jv new 0.00000000 btc
m/0/0/0/005 1KVr1QjiUsTPCyQhaGNth8BZwYaBydPTpp new 0.00000000 btc
m/0/0/0/006 184EYAbYveTYYLNW1ewTFV4ysEqpAswvN4 new 0.00000000 btc
m/0/0/0/007 14jmzkDjF2Ruyn3kQwYsaS2quorjyqsZ72 new 0.00000000 btc
m/0/0/0/008 1XDsccCJLDGsW9VvzaFT2kjS332wJnqwr new 0.00000000 btc
internal addresses m/0/0/1/
m/0/0/1/002 1Ei1yo2VDHQnHGUoaUZrJ7uWNovZU6cqg9 used 0.01039038 btc
for mixdepth=0 balance=0.08505485btc
mixing depth 1 m/0/1/
external addresses m/0/1/0/
m/0/1/0/001 17bSF43rrcK6stgAXbbEEwBQJMSMh2pMhX new 0.00000000 btc
m/0/1/0/002 1Hi5j3iyjUmGstQq5tLYjMTKNoVvZ5czCB new 0.00000000 btc
m/0/1/0/003 19VZdjKBPXTzcWqsfLpjzPs1do1KWcPncK new 0.00000000 btc
m/0/1/0/004 1FFRrzqMZbdDxdX75p7UrjY9crLi1bzGEb new 0.00000000 btc
m/0/1/0/005 1BSJ5Y77hBwRwKSwZXKnDBWZF3WikC3PNo new 0.00000000 btc
m/0/1/0/006 18x4KsBcUQnrGccVHvHWSRb8gco8nKUyja new 0.00000000 btc
internal addresses m/0/1/1/
m/0/1/1/001 15tt2crkHQsVKWBfXJoufZND626HgzrDKW used 0.01245286 btc
for mixdepth=1 balance=0.01245286btc

36. Masternode Mixing

37. What is Dash?
Fork of Bitcoin
Launched 18 January 2014
Initially named XCoin, then Darkcoin, then Dash (“digital
cash”)
Initial goal was to add privacy features to Bitcoin
Current blockchain approx size: 2GB
Current valuation:
40-50m USD market cap
(compare Bitcoin 6-7bn USD)
6 400 000 Dash @ 6-7USD
(compare Bitcoin 15 500 000 coins @ 400-500USD)

38. What is a
masternode?
Bitcoin:
Miner:
secures the blockchain
100% of block reward
Node:
stores, validates and shares the blockchain
0% of block reward
Dash:
Miner:
secures the blockchain
45% of block reward
Masternode:
stores, validates and shares the blockchain
provides higher-tier services eg mixing
45% of block reward + fees1000 Dash
collateral

39. Denomination
mixing peer mixing peer(s)
40 dash
5 dash
23 dash
10 dash
17 dash
tx
10 dash 10 dash 10 dash 10 dash
1 dash 1 dash 1 dash 1 dash
1 dash
tx
10 dash 10 dash 10 dash 10 dash
1 dash 1 dash 1 dash 1 dash
1 dash
numbers slightly simplified (no duffs)

40. Masternode mixing
masternode
mixing peer
mixing peer
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash

41. Masternode chaining
masternode
mixing peer
mixing peer
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash
mixing peer
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash

42. How does it look?

43. Dash-QT: 1

44. Dash-QT: Empty
wallet

45. Request payment

46. Send Dash to wallet

47. Check Dash received

48. Wait for Dash to
confirm

49. Start mixing

50. Mixed coins pending

51. Incoming
denominations

52. Transactions

53. Transactions

54. reateDenomination

55. Denominate(mix)
mine not mine

56. Privacy threats

57. The nosey node attack
masternode
mixing peer
mixing peer
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash
mixing peer
10 dash
10 dash
10 dash
10 dash
10 dash
10 dash👹
randomly chosen from a pool
of (currently) 3500-4000 masternodes
chain depth
2-8

58. Probability of snooping
successAttacker Masternodes /
Total Masternodes
Depth Of The Chain Probability of success (n/t)^r DASH Required
10/1010 2 9.80e05 10,000DASH
10/1010 4 9.60e09 10,000DASH
10/1010 8 9.51e11 10,000DASH
100/1100 2 8.26e03 100,000DASH
100/1100 4 6.83e05 100,000DASH
100/1100 8 4.66e09 100,000DASH
1000/2000 2 25% 1,000,000DASH
1000/2000 4 6.25% 1,000,000DASH
1000/2000 8 0.39% 1,000,000DASH
2000/3000 2 44.4% 2,000,000DASH
2000/3000 4 19.75% 2,000,000DASH
2000/3000 8 3.90% 2,000,000DASH

59. Other threats
(as of Sep 2014)
Source: Reply to Kristov's paper by Evan Duffield on Dash/forum

60. That’s all the threat stuff I had time to prepare

61. Summary

62. References
CoinJoin Wikipedia article:
https://en.wikipedia.org/wiki/CoinJoin
CoinJoin: Bitcoin privacy for the real world (Greg Maxwell):
https://bitcointalk.org/index.php?topic=279249
Joinmarket - Coinjoin that people will actually use (Chris Belcher):
https://bitcointalk.org/index.php?topic=919116.0
Dash whitepaper (Evan Duffield, Daniel Diaz):
https://www.dash.org/wp-content/uploads/2015/04/Dash-
WhitepaperV1.pdf
An Analysis of Darkcoin’s Blockchain Privacy via Darksend+ (Kristov
Atlas):
http://cdn.anonymousbitcoinbook.com/darkcoin/darksend-
paper/Atlas_Darksend-Analysis-v001.pdf