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Using Rotating Signers to Scale IBFT Consensus Algorithm

Enterprise blockchains are diverse, and can be built using a number of different technologies and protocols..  Consensus algorithms are an example of this: depending on the objectives, member requirements or technology mandates, different consensus algorithms can be used to achieve collective agreement across member nodes on the state of a transaction. 

Many enterprise consortiums use IBFT, a great solution for reaching consensus in an untrusted environment.  But this protocol can be quite resource intensive with a limit on how many nodes can participate as validators. That’s why Kaleido launched a new feature, Rotating Block Signers, to enable broader participation and minimize resource usage

 

Why IBFT?

In a private, permissioned blockchain, members must be invited to join the network.  Each node can be identified and tied to a member organization, underpinned with digital x509 certificates for trustworthy and authoritative identification.  

Istanbul BFT (IBFT) is a popular choice for consortia where trust among members is not assumed.  Using IBFT, each block requires multiple rounds of voting by a determined set of validators to arrive at a mutual agreement, which is recorded as a collection of signatures on the block content.  That allows the network to continue to function correctly even if some of the nodes act dishonestly.  

IBFT provides a great solution for reaching consensus in an untrusted environment, but it is also resource intensive with a limit on how many nodes can participate as validators.  In Kaleido, the upper limit of validators is set to 20 for IBFT. The upper limit is fine for smaller consortia, but as the network grows, you might want to include more nodes as validators to extend participation to newer members.  

 

Rotating Signers

Blockchain is collaborative by nature, and architected to provide an equitable framework for everybody to participate. That’s why we introduced Rotating Signers – another industry first from Kaleido.  This new feature allows you to rotate the group of validators used in an IBFT implementation, enabling broader participation by the consortia members. Using this new feature, you can:

  • Set the number of overall signers included in each round.
  • Set the number of nodes swapped in and out of each round.
  • Set the timing for how often signing nodes are rotated in and out.

This flexible new feature provides a simple way to ensure equality of participation for consortia that grow to hundreds of participants.  And just like every other feature of Kaleido, there’s an API that allows you to do everything you can do in the console, including a query API to immediately see who comprises the group of singers on current and future transactions.  

 

Enabling Rotating Signers on Kaleido

Learn more about Kaleido’s Rotating Block Service

  1. To enable the Rotating Signers service, just click on the purple “Add” button, then choose “Add Services”. 

  1. Click on the purple “Add” button on the Rotating Signers tile.
  2. Configure the Rotating Signers service with your choice of values for:
  • Target number of signers
  • Rotation Interval
  • Rotation Size
  • Rotation Algorithm

Once you enter your preferred values, click on the “Activate” button.  You are now enrolled in the Rotating Signers service. 

 

  1. That’s it!  You are now using the new service.

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