Big Data era of the Internet, people are exposed daily data, see rating shopping, watching stock reports ...... However, this "everywhere is a trap," the era of data really credible? They have not been tampered with before? (Chen: 189-2212-1563 micro-electro same number)
Some time ago, Japan's third-largest steel giant - Kobe Steel has been discovered tampered aluminum products performance data; A-share listed companies' financial statements fraud case in recent years has frequently been exposed ......
It is often said, without tampering with the real data is the basis of good faith, generally, most people rely on government legislation and public exposure, to prevent malicious tampering by raising the punishment for fraud, but the good law needs good " police ", if you can not find tampering, it can not completely avoid risks and losses. If there is a technical means, both to increase the difficulty and cost of data tampering, but also allow others to quickly and cheaply test of whether there has been tampering, fraud prevalence of this situation will be greatly improved.
2017, skyrocketing bit of money raised concerns, in addition to the legendary consuming power, Bitcoin what is new contribution to human beings? It is important that Bitcoin build a highly credible books, completely eliminate tampering of books.
This is because the bit block chain technique uses credits as the underlying support, so that the block chains in the absence of administrative supervision, but also to ensure that money can not be tampered after the transaction data is written books. In this regard, the industry chain will block the field called the "immutability."
So, how should this invariance understand? It is how to achieve? It is ordinary people and what is the relationship? This paper attempts to answer these questions.
What is the invariant chain block?
In general, the specific meaning invariance means that certain things will not change over time.
Example bits currency, transaction data is constantly extended, and therefore within the scope of the block chain, invariance refers Once the transaction is written to the books, no one can change it. By block chain, a provider of data can prove that the data they provide has not been changed, and the receiver of the data it receives clear data has not been tampered with.
It is worth noting that this invariance is accessible for all, accounts books and bank block chain maintenance is not the same. For bank accounts as a normal user, you can only read your own books, but can not make changes to historical data, however, a number of other people of higher authority, such as the bank's internal system administrators have completely revised data ability. The block chain technology is to ensure that anyone, including system administrators, it can not be modified history.
However, the invariance block chain technology is not absolute.
As a simple example, you write a message ready to send, before sending it, you can modify it at will, which no one knows. If you have been sent to a friend, this information have a certain invariance for you, you want to change it, you can ask your friend to delete the original message, and then send you back, so that others I do not know you modify this message. So, if you give a lot of mass people? For you this invariance is very strong, because you have to convince each and every message recipient to delete the original message, in theory, this can be achieved, but the reality very cruel, the greater the number of mass, the greater the difficulty of changing data.
Block chain is also based on the same principle. For those who tampered with data, the data tampering is not difficult, difficult place that let people discover how such tampering, as long as other people make quick verification data has been tampered with, and it shows that the tampering is a failure. This increases the difficulty in disguise modify certain things.
Taken together, the invariant chain block contains the connotation of two aspects: First, to the attacker manufacturing difficulties, the second is user-friendly detection of tampering, however, the specific process is how to achieve it?
How invariance block chain to achieve?
In the financial sector, the books record the transactions of assets and cash resources, financial records is very important. Each of us has a corresponding flow record in the bank, while the sequence between each record is usually sorted and numbered chronologically. This flow-through of books for people who have rights, it is very easy to tamper with, for example, they put a few records the contents of the slightly modified, not carefully view the contents of hard to see.
The following figure shows an example: Some people put a single line on page 4 has been modified, it can be hard to tell the difference before and after, because the books are not enough to change significantly (see figure below). Obviously, this general ledger tampering is very simple, and check if tampering is very difficult.
According to this principle, any tampering with the user able to reflect on the changes in the page number. To make it easier to detect, we hope that even if only a very small modification of the contents, page numbers can be unrecognizable. One benefit of this is that those who tamper difficult to master page changes. So, if there is a ledger, he put the contents of each page and the page number to associate, regardless of the contents of page 4 what changes will occur page mutations, such as tampering with the page number on page 4 became 40, in this case, tampering can be detected quickly. This is the first major principle block chain tamper-proof: page content and sequential numbering to associate.
But this also brings a real problem for the accounting process - due to the uncontrollable page number, page number difficult to generate a continuous time of billing, then, the order books of how to maintain it block the chain, in a newly added? page books, when he wrote the beginning of the previous page of the books of this page, so that we can account for all the sorted page, a typical shape of block chains can be expressed as the following figure:
The first rule is that a valid books: You must ensure the consistency of two pages front and back. Once the link is not on the page, indicating that there are fake accounts.