A bitcoin, which is a representative of virtual currency, is a non-centralized digital currency based on transaction settlement by P2P communication.
Instead of accumulating data on one server, data is accumulated on "nodes" that make up the network so that transaction data can be verified with each other.
Information on exchange of currency is recorded publicly for units called "blocks".
A block is a collection of transaction data, it can correspond to accumulation of various data, not only the most recent data, but also "has data on a block processed before one" is a feature.
By connecting a block to the previous block, a chain of information will be generated.
Thus, the underlying technology of bitcoin is the reason it is called "block chain".
<h2>About the risk of virtual currency</h2>
People who already use bitcoin on online wallet or trading service think that personal information and accounts are tied up.
However, in order to identify "where the bit coin transaction took place", this information alone is not enough.
Many criminals are distributing bit coins among multiple accounts in preparation for the financial situation to be disclosed.
By repeatedly conducting a number of transactions and building a complex trading network, they will "try not to identify the gold source".
Remittance of bit coins is conveniently completed and it is possible to move assets instantaneously.
Therefore, tracking funds transfer is extremely difficult, and even if there is a doubt that illegal activities will take place, it is not easy to stop it.
<h2>Is the virtual currency really evil?</h2>
On the other hand, there is an opinion saying "exaggeration too much" about the danger to crime by the anonymity of bitcoin.
Personal information is not recorded in the transaction record on the block chain, but the public key of the account involved in the transaction remains in the log.
The details of all transactions remain as records on the block chain and it is also easy to access that data.
Therefore, by tracking the account indicated by the public key, you can monitor how the asset moved by bitcoin.
Also the virtual currency is now being accepted as a formal investment.
For these reasons, some people claim that the bitcoin used for criminal activity is "constituted by a group of criminals" to help "grasp the large trading network".
<h2>Possibility as a "crime prevention measure" of the "block chain"</h2>
It is important to consider block chain technology as a crime prevention measure separately from bit coins and other virtual currencies.
Block chains are not used as a specific crime prevention measure, and the "transparency of records" on the block chain serves as a breakwater for information manipulation such as tampering.
Attempts to utilize block chain technology for systems requiring more stringent security such as real estate registration and voting system have already begun, and efforts to private applications such as financial transactions and SCM (material procurement operation) are also active is.