IOTA Chrysalis phase 2: Transaction size will decrease 20 times

  • With the release of IOTA Chrysalis phase 2, the transaction size within the Tangle will decrease from around 5 to 8 kilobytes (Kb) for a bundle to 350 bytes for an atomic transaction.
  • As a result, the messages per second (mps) could increase about 20 times.

IOTA developer Hans Moog has revealed new details about Chrysalis phase 2 via Discord. As already announced with the announcement of Chrysalis, the upgrade involves a change from the bundle concept to atomic transactions. IOTA David Sønstebø stated in February that the upgrade will be accompanied by numerous improvements:

This will reduce network overhead, reduce signature verification burden, improve spam protection and congestion control, and reduce length of Merkle proofs (for future sharding). In addition, it will reduce implementation efforts and increase maintainability of our core node software.

IOTA Chrysalis phase 2 shrinks the size of a transaction

But what exactly does the changeover mean? Until now IOTA has used the concept of bundles to create transactions. Bundles are transfer packages that contain at least one input and one output transaction and can also include zero value transactions. Until now, the individual transactions have been linked to each other via the so-called “trunk”.

Bundles themselves are atomic transactions, which means that either all transactions are accepted by the network or none. Simply put, at least 3 transactions must be used to create a simple transfer: 2 transactions for input and their signature and one transaction for the rest (without signature). The problem with this concept is that these bundles have a fixed size regardless of their content.

In favor of the advantages mentioned above by Sønstebø, this concept will be replaced by atomic transactions with Chrysalis phase 2, so that a single transaction is atomic. As Hans Moog explained via Discord, the transaction size will be more than twenty times smaller. As a result, messages per second (mps) will also increase about twentyfold, according to Moog:

But I agree bundles are bullshit and that’s why they are removed next – currently the bottleneck is network throughput and ternary conversion.

Currently a bundle is around 5-8 kb.
After Chrysalis part 2 its around 350 bytes.
So more than 20 times smaller.
So mps should be around 20 times higher as well – especially without the ternary crap.

So if you say a bundle has 3 transactions and therefore compare 1000 iota tps to 333 btc tps then after part 2 you will have 4-5000 “real” tps. I think it might also end up in the 5 digits since we are also having data transactions which might be smaller.

In addition to the improvements made by the atomic transactions, Moog also revealed that the IOTA Foundation has already started work on the specifications for the new consensus model, the “Tangle Multiverse”:

It’s true. We are writing the specs now. […] Well I have been thinking about it for a really long time but never had the time to write any specs as we were supposed to work on fpc. So it’s very few open questions about how it should work. Rather than ‘does it work’.

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