# Ganymede Protocol Summary of Ideas

*Draft v1.1*

## The purpose of Ganymede Protocol

Ganymede protocol targets *dapps that need high composability and high degree of decentralization*, such as Decentralized Finance applications.

The purpose of Ganymede is to introduce *a set of mathematical improvements to SKALE provable consensus algorithms*, that enable running consensus in an environment of *a highly decentralized and powerful blockchain*, where large number of dapps can interact with each other **in a highly-composable way**.

Consensus performance it critical, when running *a large number of interacting dapps on a common chain*.

Therefore, we envision blockchains that implement Ganymede protocol to **execute on computationally powerful nodes that have high network bandwith and vast storage available to them**.

Our goal is to develop Ganymede Protocol algorithms **in cojunction with Levitation protocol**. Levitation protocol can then be be used **to provide ZK functionality on blockchains**, implementing Ganymede protocol. This enables high security transactions that can be **verified on ETH mainnet using Zero Knowledge proofs**.

## ZK-native from the start

Ganymede protocol will transition its cryptographic internals, such as state root computation, to **ZK-native cryptographic algorithms** that **enable fast ZK-proof generation**, ads well as **verification of the corresponding ZK proofs on ETH mainnet**.

## Minimalistic design

**We target minimalistic design**, that **reuses, as much as possible, the existing mathematics and code base**, as well as allows faster implementation time.

Our goal is for Ganymede protocol to introduce **as few changes to as possible** to existing SKALE consensus algorithms, while still reaching **the goals of high composability and high decentralization**.

## Ganymede weighted consensus

Ganymede plans to introduce a set of improvements to **make consensus more flexible**.

In particular SKALE consensus algorithms assume that **each node has the same voting rights in the blockchain**. Ganymede uses more flexible algorithms,
that introduce **the notion of node weight**. The power of a particular node in the system **is be proportional to its weigh**, instead of being equal for all nodes, as in the current SKALE consensus protocol.

We envision the node weight to be proportional to the total validator stake in a Ganymede-enabled blockchain.

This means, that instead of running multiple nodes, a validator of a Ganymede-enabled blockhain, **may run a single powerful node with a large weight**. This can **significantly improve validator costs** and **enable validators to run more powerful nodes**, improving overall chain performance.

## Aggregated signature implementation

Current SKALE consensus uses BLS threshold signatures, that **require DKG (distributed key generation) algorithms ** to execute each time a node joins or leaves the chain.

Since the goal of Ganymede protocol is to **enable execution of larger blockchains with faster addition and exit of nodes**, Ganymede protocol plans to provide a new implementation of **aggregated BLS signatures with long term BLS keys*.

The aggregated signature impelementation **will not require running of DKG rounds on each node join and exit**.

Adding aggregated signature to SKALE consensus protocol **will require source code modifications in multiple places**. Essentially, one will need to **add aggregated signatures as an option** in each place in the code, where currently BLS threshold signatures are used.

## Transaction fees

Since a Ganymede implementation is **envisioned to be executed in an environment where multiple Dapps interact on a single powerful chain**,
we expect Ganymede-enabled systems to have non-zero transaction fees. As in general we target ETH compatibility, the protocol will use transaction fee algorithms compatible with ETH transaction fees math, in particular EIP-1559.

On the other hand, as Ganymede is envisioned as a high performance chain, its architecture will target minimizing transaction fees as much as feasible, **similar to other high performance blockchains.**