Decentralized payment systems
Alice‘s
bank
Bobs
bank
Alice Bob
Edmund
Alice sent this
coin to me!
Alice
Bob
priv
pub
What if I send the
same coin to both
Edmund and Bob?
Consensus-Algorithm
PoW-Mining
▪ External resource (calculation power) is used – the reward is the underlying cryptocurrency
▪ Finality is achieved after ~ 6 blocks (in Bitcoin)
▪ Randomness of participants due to the mathematical problem
▪ Faster block solving times result in less security
PoS-Mining
▪ Internal resource (relative stake of coins) is used
▪ Randomness needs to come out of the system
▪ Block solving times are limited by the speed of the participants network
Choose a participant who creates the next block
Oracles
Decentralized data stream
▪ Parties „bet“ on a specific result
▪ Median is defined and set as the correct result
▪ All parties inside of a certain quantile of the median get a reward
Central service provider
▪ A trustworthy third-party delivers data to the blockchain
▪ Can be used by other programs on the blockchain
Provide reliable external data to the blockchain
Decentralized payment systems
Oracle4. Delivery confirmation
2 of 3
Oracle can be used if problems arise.
The tracking ID could bes used as a
proof that the delivery happened
Smart
contract
Buyer Seller
1. Payment of goods2. Verification of the
payment
5. Allow transaction
to the seller 5. Allow transaction
to him or herself
6. With two of three
confirmations: Payment
goes to the seller
3. Delivery of goods
Token systems
Way ofminting
AutomatedDirectly
controlled
Tradeability
Freely Not tradeable
Divisibility
Freely divisible Not divisible
Amount
Fixed amountVariable amount
Identity systems
1. Data to service2. Verification
3. Confirmation /
DenialSmart
contract
pub pub
User Service
User
pub
KYC-Provider
Smart
contractWebsite
1. Data to KYC-Provider
2. Post card with
verification code
3. Enter the
verification code
4. Confirmation
5. Registration
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