Introduction to Multi-signature Technology

Content

Generally speaking, a Bitcoin address corresponds to a private key, and the use of funds in this address requires the owner of the private key to initiate a signature. The multi-signature technology, in simple terms, requires multiple private key signatures to be effective when a sum of funds is used. For example, a certain fund corresponds to 3 private keys, and at least any 2 of these private keys must participate in the signature before it can be used. Only 1 private key participates in the signature is invalid. And this 2/3 can be extended to any m/n, such as 3/3, 1/5, 6/11, etc. Of course, m must be less than or equal to n.

1. Intermediary guarantee

This is exactly the model that Bisu.com is testing, in short, the model of Alipay. The customer pays first before the merchant delivers the goods, but the merchant does not receive the money directly after payment, but waits for the transaction to be completed before confirmation. After the customer pays, the money is neither controlled by the customer nor controlled by the merchant. If there is a dispute in the transaction, the intermediary can arbitrate and return the funds to the customer.

The above is the same as the Alipay model we are familiar with, but what is the extra meaning of Bitcoin multi-signature? That is, while the money is out of the control of the customer and not yet controlled by the merchant, it cannot be controlled by the intermediary platform either. In other words, the intermediary platform cannot use the money at will, let alone run away with the money.

Compared with Alipay, Bitcoin's intermediary secured transaction limits the ability of intermediaries to do evil. For example, during the transaction, the intermediary takes the temporarily "frozen" funds to gamble (or invest), and then loses money, then the merchant will not receive the money. Or, if the intermediary cheats or confiscates the funds according to certain "regulations", then the merchant has to bother to find the intermediary to collect debts. For example, Taobao may completely pretend that Bitcoin is illegal, and the transaction has been reached by both parties. The transaction was confiscated, the seller was helpless, and the buyer was helpless (this seems to have happened).

To put it simply, in the traditional Alipay model, the introduction of intermediaries on the one hand adds some elements that make transactions more reliable, but on the other hand adds new instability factors. That is to say, on the one hand, your Trust does not need to be that high, but on the other hand, it additionally requires unconditional trust in the fairness and reliability of the intermediary platform.

With the support of multi-signature, for example, customers, merchants, and intermediaries form a "2/3", which means that the addition of intermediaries only has a positive effect on the improvement of reliability, and there is no new addition at all. Certainty. In other words, if the two-person transaction can be successful originally, it must still be successful when a new intermediary is added. As long as the two private keys of the customer and the merchant confirm the transaction, the entire transaction is completed, and whether the intermediary is trustworthy has no effect. The intermediary has power only when there is a disagreement between the customer and the merchant.

Changing the number of m/n and the weight of the private key distribution, it is also possible to design various more complex intermediary models, for example, the introduction of 3 guarantors at the same time, when the two parties in the transaction are inconsistent, 2 of the 3 guarantors are required to make a ruling such as.