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# System prepended metadata

title: PoA Blockchain design

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# PoA Blockchain design

Let's draft a design for a centralized PoA blockchain with the following requirements:

* 160 bit addresses, state space for each address is a mapping (256 bits => 256 bits)
* every transaction contains a list of reads and writes to this mapping (10 reads + 10 writes in average)
* block time of 1 second

API requirements:
* submit a transaction
* get user balance
* get transactions by block number

bonus: 
* dry-run a transaction (at arbitrary block height)


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