2. NATIONAL CURRENCIES
• €5000 stolen from cash card;
refunded by bank
• Capital controls in Greece
• €8.3bn haircut in Cypriot bank
deposits
• 1.3bn Indians asked to hand in
cash
• Zimbabwe currency
• Venezuela currency
• KYC/AML
+ -
3. CRYPTOCURRENCIES
• No capital controls
• Known currency supply (for
some coins)
• No KYC/AML within the
cryptoeconomy
• Price you pay for freedom: you
must protect your keys
+ -
4. AGENDA
• What to protect?
• From what threats to protect?
• How to protect?
5. BITCOIN KEYS
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access accident account
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Mnemonic Seed
Phrase
Public
Private
Bitcoin private keys
Bitcoin receive addresses
0.3BTC 0.5BTC
6. NOT YOUR KEYS, NOT YOUR COINS
• Custodial wallets/exchanges for trading
• Custodial wallets can be hacked
• Exchanges might not be solvent
7. THREATS
• Theft
• Destruction
• Take them with you to your grave
• Multiparty/Institutional ownership
• Receiving coins on your behalf: web server, teller/waiter
• Privacy
• Low-entropy keys
abandon ability able about
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access accident account
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Mnemonic Seed
Phrase
Public
Private
Bitcoin private keys
Bitcoin receive addresses
0.3BTC 0.5BTC
8. TOOLS
• Use these tools to protect your coins
• They are building blocks to mix and match like LEGOs
9. MEMORIZE THE SEED PHRASE
• Useful if you have to walk from Syria to Germany and you have to
swim across the Mediterranean
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Mnemonic Seed
Phrase
10. CRYPTOSTEEL
• Store your seed phrase
• Protects against fire
• Protects against water
• Split in two: password and
encrypted seed
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Mnemonic Seed
Phrase
11. GENERATE YOUR OWN SEED PHRASE
https://iancoleman.io/bip39/
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Mnemonic Seed
Phrase
13. RISKS OF SOFTWARE WALLETS
• Insecure, general-purpose computing devices
• Seed copied off screen
• Private keys stolen after you unlock your wallet
15. ONE ADDRESS PER TRANSACTION
• Wallets automatically
generate new addresses
• Preserve your privacy
• Preserve everyone’s privacy
16. DEAD MAN’S SWITCH
• “If something happens to me”
movie line
• Does nothing as long as we
are alive
• Acts when we stop
demonstrating signs of life
• Google’s Inactive Account
Manager
• Test it!
17. LAST WILL AND TESTAMENT
• Gifting €5,000 vs gifting
€500,000
• So your loved ones can spend
your coins
• Read articles by Pamela
Morgan
https://medium.com/@pamela
wjd
18. SHAMIR’S SECRET SHARING
• Break any secret into X pieces
• At least Y pieces required to reconstruct the secret
• Y<=X
• e.g. 3 out of 5
• https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing
20. MULTISIG USE CASES
• Authorizing payments as a group of people: 2 of 3: CEO, CFO,
Accountant
• Gift your coins to your descendants after you get hit by a bus: 2 of 4:
your phone, your hardware wallet, bank vault, a relative
• Use your coins with untrusted wallets: your phone, your computers,
bank vault
• Use your coins with an offsite wallet: your phone, authenticated
payment provider, bank vault. See https://greenaddress.it
• Payment escrow: 2 of 3: Buyer, Seller, Trusted Escrow Agent. See
https://www.openbazaar.org
22. COLD WALLETS
• Private keys only used on an offline computer
• Private keys can be permanently or temporarily stored
• Can sign transactions
• http://docs.electrum.org/en/latest/coldstorage.html
abandon ability able about
above absent absorb
abstract absurd abuse
access accident account
accuse achieve acid
acoustic acquire across act
action actor actress actual
Mnemonic Seed
Phrase
Public
Private
Bitcoin private keys
23. WATCH-ONLY WALLETS
• Wallets with public addresses only
• Can view balance
• Can generate receive addresses
• Can generate transactions but cannot sign them (cold wallet will do
the signing)
• Can broadcast signed transactions
Public
Private
Bitcoin receive addresses
0.3BTC 0.5BTC
24. TIERED WALLETS
• Cellphone: spending cash
• Hardware wallet: savings
• Multisig with cold wallets: long term investments
25. NLOCKTIME TRANSACTIONS
• Sign a transaction with nLockTime into the future e.g. next year
• Give the transaction to recipient
• Move the funds off your address if you are still alive and repeat
26. THANK YOU!
• WEACCEPTBITCOIN.GR
• Meetup in Thessaloniki and Athens
• Slack (online chat)
• Greek section on BitcoinTalk forum
• How to accept, spend, buy and sell Bitcoin in Greece
