8. The Genesis Block
First block was hand-crafted
11Pe5Gf2MTT5LvDvN
Az1PQeiDPfLSm7ifa
Rewards 50 unspendable btc
ht:/lcepoe.o
tp/bokxlrrcm
9. Wallet
The bitcoin address is the public key.
Private key used to sign transactions
Unlimited free addresses
No tx concept... use address aliases
vanitygen
10. Transactions
Created by any client
Signed with source address priv key
Multiple destination addresses
Need to be verified ~6 times
Verification times depend on fee
Cant be revoked
User defined fee
11. Miners
Enforce the blockchain creating blocks
Group some random transactions
(even invalid)
Bruteforce a seed to get a small hash
Difficulty depends on network power
Reward for solved block (25btc + fee)
12. Pools
Miners cant solve blocks fast enough to
be profitable
Join forces and reward shares
Proof of work with lower difficulty
PPS/PPLS/Prop/DGM/..
14. Other currencies
Bitcoin is based on SHA256 and ECDSA
Known as ALT coins
Several forks appear
Implement new core rules
Most use SCRYPT to avoid ASICs
20. Fix 51% attack (proof of stake)
Less power consumption (ppcoin)
More coins (feathercoin)
Unlimited coins (Novacoin)
Faster transactions (terracoin)
Enhance anonymity (zerocoin)
Mixed transactions (anoncoin)
21. Anonymity
Every transaction is public
Most trading sites require personal ID
Many addresses can be tracked down
from web/tw/fb/mail signatures.
Not designed to be anonymous
22. Gateways
There are payment gateways that
sellers can use to accept bitcoins as
payment and receive euro/dollar in
change without any extra effort.
or you may also want to trade..
23. Trading
Many sites allow to trade between
crypto-currencies, and also with real
cash like euros or dollars.
hts/bttm.e
tp:/isapnt
hts/vrue.o
tp:/icrxcm
hts/mgxcm
tp:/to.o
hts/bcecm
tp:/t-.o
27. Alerts
Broadcasted messages signed by
Satoshi, Gavin, or Theymos.
Notify about network problems or
security vulnerabilities
Put client in safe mode (isolate node)
32. Rainbows
Impossible to cache all combinations
prevhash (32 bytes)
tx counter (1-9 bytes)
timestamp (4 byte)
seed (4 byte)
N random transactions
33. Hacking
Lite clients and bitcoin banks have been
shown to be weak.
Many btc banks or pools got hacked
Sniffing weak client communications
DoS manipulates the mining power
SCAM (social engineering?)
Trojans/Games/Webs with miners
