To: bitcoin between main chain and side chain transfer mode five

To: bitcoin between main chain and side chain transfer mode five

Since 2014, the side chain was first publicly discussed, this concept has been a lot of publicity from the bitcoin community. Essentially, the side chain allows users to transfer between bitcoin bitcoin blockchain and other different function block chain.


The side chain is currently under development include RSK (Rootstock), more flexible and intelligent platform contract an Ethernet workshop; Mimblewimble, a method for improving the bitcoin blockchain privacy and experimental method of expansion; BitcoinHivemind, a prediction based on a block chain platform.

Will bitcoin transfer from the main chain to side chain, these bitcoin first will be frozen in the main chain, then activate the chain in second; this is a two-way link (two-waypeg). According to who or what to control these are frozen in the bitcoin on the main chain of funds for the bidirectional hook mechanism, there are 5 famous solutions.

1. single party custody

The easiest way to implement bitcoin and the side chain is through the bidirectional linked funds will be sent to a single backbone hosting party, and then activate the funds in the side chain. However, this is an obvious question: This is a complete solution of the center.

In reality, by a mechanism of control of frozen funds and sent to the side chain and from bitcoin Bank (such as Coinbase or Xapo) to withdraw funds without too much difference. In this way, you can use these bitcoin bank internal books as bitcoin side chain.

If a central agency intends to complete control of the frozen funds, it is best able to function through a central server instead of a new block chain to extend these funds.

2. alliance mode

If you pass a method of multi signature address using the notary union to replace the safekeeping party single, then things will become more interesting. In this mode, the entity must sign to confirm the alliance capital flows to the side chain, so in order to freeze the theft of the main chain of the bitcoin would break more institutions.

The Blockstream issued a “strong alliance” recent white paper (white paper Download), is essentially a union type bidirectional linked system. Liquid is a kind of side chain Blockstream created, using powerful alliance mode. This side chain is used in between the center of the bitcoin bitcoin transfer mechanism, such as exchange, and faster than the public bitcoin blockchain.

One of the main selling point of a single hosting party and alliance mode of side chain scheme is that they don’t need the bitcoin protocol for any change.

3.SPV side chain


The side chain of SPV is the first “white paper” in the side chain to the center of the bidirectional linked initial idea.

The side chain of SPV using the SPV certificate to transfer bitcoin to side chain. SPV proved to be a method for proving the transaction exists, by proving that a small amount of data associated with a specific transaction in the block.

In other words, received a pen marks the mobile bitcoin transaction between the main chain and side chain in block, SPV side chain will bitcoin transfer between the main chain and side chain. However, the SPV side chain to bitcoin soft branch.

Unlike other two-way mechanism linked to the side chain of SPV is not directly to the control of the main chain of bitcoin to a trustee; however, occupy the majority of the number of miners can be generated and the ability to create fraudulent SPV proved that they can indirectly control these funds, including the ability to send money. Nevertheless, there are several ways to alleviate this problem.

The 4. driving chain


The driving chain is “a side chain side chain mentioned in alternative white paper”. In the drive chain, the miners sends signals to the current state of the side chain. In other words, the miners essentially managed funds, they can help those who want to own bitcoin users unfreezing the funds transferred back to the main chain.

The driving chain is defined by Bloq and BitcoinHivemind founder PaulSztorc development economist.

One of the main principles of the driving chain is from the game theory perspective, miners are side chain funds hosted the biggest problem. Sztorc said that the infrastructure side chain may elaborate with the miners stealing backbone of frozen funds in the same way.

Sztorc explains the impact of this set in the original post:

“This shameless theft that bitcoin in the near future there will be no side chain of any type, bitcoin itself may fall into the miners threat (we may need to consider the use of an alternative POW hash algorithm).”

Such as the SPV side chain, the drive chain also needs to bitcoin soft branch.

5. mixed chain

The method of obtaining bidirectional linked together is possible.

For example, a concept of RSK laboratory is exploring will drive chain and alliance mode together. In other words, the miners and union members must transfer between main and side chain bitcoin bitcoin for signature confirmation.

As mentioned before, the driving chain to the bitcoin soft bifurcation, so RSK only uses alliance mode.

Although the alliance mode and driving chain model are combined, but if 90% bitcoin miners decided to merge with RSK mining, the alliance of RSK block chain model will not play any role.

Additional: extended block and soft forked side chain

Another idea is similar to the concept of side chain extension block. With the side chain is very similar to that of extended blocks allow users with different verification rules transaction block selection.

The key difference between the chain and the traditional side is extended block updated bitcoin all nodes to verify the extension of the transaction block. This means that the expansion blocks are more closely than the traditional side chain and the main bitcoin network.

The degree of separation between the block and the expansion of the bitcoin network is almost non-existent, it also means that if the extension block problem, it will be more likely to cause the bitcoin network problems.

For the side chain, there is separation layer between the bitcoin backbone and side chain, this also means that the effect is not affected by the problem of side chain backbone. Therefore, the research of side chain enterprises than on the extended chain enterprises more, such as RSK.

Recently, BitcoinCore contributor JohnsonLau issued a bitcoin protocol (BIP) to improve the draft, for the use of extended block to effectively enhance the bitcoin block size limit.

The extended block can be implemented through the soft branch, so the essential feature of the expansion block is selected by the user. Even with the extension block larger block size restrictions, users will not be forced to upgrade and verification or dissemination of larger size block. Those who wish to use the 1MB block can continue to use, and those who want to experience more people can block up the implementation based on the choice of the extension block.

Although the user can selectively use extended blocks, but the miners must upgrade and continue to tap the effective block on the main chain.

The need for the side chain and the extension block soft forked is similar to that of the major differences between the word ah soft forked side chain is mixed mining, instead of mining chain.

This article is SergioLerner’s chief scientist Rootstock laboratory recently on the Zeppelin YouTube channel based on speech and conversation with BlockstreamCEOAdamBack.

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