  Owing to Satoshi Nakamoto's brilliant idea, a P2P public ledger is shown to
be implementable in anonymous network. Any Internet user can then join the
anonymous network and contribute to the P2P public ledger by providing their
computing power or proof-of-work. The proof-of-work is a clever implementation
of one-CPU-one-vote by anonymous participants, and it protects the Bitcoin
ledger from illegal modification. To compensate the nodes for their work, a
cryptocurrency called Bitcoin is issued and given to nodes. However, the very
nature of anonymity of the ledger and the cryptocurrency prevent the technology
from being used in fiat money economy. Cryptocurrencies are not traceable even
if they are used for money laundering or tax evasion, and the value of
cryptocurrencies is not stable but fluctuates wildly. In this white paper, we
introduce Gruut, a P2P ledger to implement a universal financial platform for
fiat money. For this purpose, we introduce a new consensus algorithm called
`proof-of-population,' which is one instance of `proof of public
collaboration.' It can be used for multiple purposes; as a P2P ledger for
banks, as a powerful tool for payment, including micropayment, and as a tool
for any type of financial transactions. Even better, it distributes the profit
obtained from transaction fee, currently dominated by a third party, to peers
that cannot be centralized. Energy requirements of Gruut are so low that it is
possible to run our software on a smartphone or on a personal computer without
a graphic card.
