Titled “Rolling with Rollups: Exploring Optimistic & Zero Knowledge Solutions, Use Cases, and Impact,” this webinar will focus on the innovative concept of rollups and their potential to address scalability challenges in the blockchain ecosystem. Rollups have gained significant attention in recent times as a promising layer 2 scaling solution. During this webinar, Dr Ravi Chamria will provide a comprehensive exploration of both optimistic and zero-knowledge rollup solutions.

1. Rolling
with Rollups
Exploring Optimistic &
Zero-knowledge Solutions,
Use cases and Impact

2. Understanding Ethereum Rollups
• Ethereum rollups have emerged as a promising solution to the blockchain
scalability conundrum.
• Rollups offer a way to mitigate these problems while maintaining the
network's security and decentralization.
• Ethereum rollups are second-layer solutions that bundle or "roll up" multiple
transactions into a single proof, which is then submitted to the Ethereum
main chain.
• This approach allows for a significant reduction in gas fees and an increase
in transaction throughput by offloading computation and storage from the
main chain.
• Rollups retain the security guarantees of Ethereum by using smart contracts
to enforce rules and validate data.

3. How Ethereum Rollups Aid Scalability
• We can post two types of information on
most blockchains: transactions and data.
The storage of transaction information and
on-chain processing can be heavy for the
mainnet.
• On the other hand, data resulting from a
transaction is less heavy and remains the
same no matter the number of transactions.
• It is similar to how a cheque weighs the
same irrespective of the amount on it.
• So, instead of storing a whole transaction
and processing it, blockchain rollups process
and submit more transactions in one single
piece of data.
Rolled up Rolled up Rolled up
proveFraud()
execute_L2_tx(s2, tx2)
!=s3
Ethereum
Rollup

4. Types of
Ethereum
Rollups
ZK
Rollups
Optimistic
Rollups
1
2
Two main types of rollups are
distinguished by their underlying
cryptographic proof systems:

5. • Optimistic rollups rely on the assumption that all
transactions conducted outside of the main network
are valid.
• However, they provide a window for users to challenge
invalid transactions by submitting fraud proof.
• The invalid transaction is rejected if the fraud proof
is verified, and the user who submitted the proof
is rewarded.
• Optimistic Rollups offer increased throughput and
reduced gas fees but have a longer finality due to
the challenge period.
• This trade-off makes them suitable for specific
use cases where instant finality is not crucial.
The Idea of Optimistic Rollups

6. 5 Steps in Optimistic Rollups
A group of validators check the validity of the
transaction. If valid, the validator will include it in a
block.
Once a certain number of transactions have been
validated, validators aggregate them into a single
block. This block includes a proof that shows the
validators have agreed on the state of the off-
chain system.
Once the block is complete, the validators will
submit it to the Ethereum mainnet. The block
includes a single transaction that updates the
state of the Ethereum contract that corresponds
to the off-chain system.
Finality and dispute resolution
After the block has been submitted to the
Ethereum mainnet, it is finalized and cannot be
changed.
However, if there is a dispute about the validity of
a transaction, anyone can submit a fraud proof to
challenge the block's validity.
If the fraud proof is accepted, the block is
reverted, and the offending validator stake is
stashed.
Off-chain validation Block aggegation
Block submission
Submitting
transaction

7. Architecture of Optimistic Rollups
OVM
Tx
(Calldata)
Fraud Proof
Challenging
Layer2
(optimistic-
Rollup)
Layer1
(Ethereum)
OVM
From a technical point of view, optimistic rollups are managed by an architecture:
• Smart Contract: A series of smart contracts on Ethereum store roll-up blocks and track the state
• OVM: A virtual machine performs computations and stores off-chain state off the main chain. This
mechanism allows you to act as a layer 2 for optimistic rollups. It is also called Optimistic Virtual machine;
in addition to Off Chain Virtual Machine, however, separate from the Ethereum Layer 1 EVM.

8. How Fraud Proofs Work
Anyone who wants to produce a block
must provide a bond i.e., ETH to be tied
up first, a system similar to a Proof of
Stake, so he can be punished with
slashing if he behaves badly.
Similarly, even those who provide fraud
proof that is not true can suffer
slashing as they have to commit funds
with a bond (a sort of guarantee)
Pre-State Root: 0x1245f9
A B
A C
B C 10
0xbc601f
D:210
C:170
B:110
A:20
The Rollup smart
contract can
store the entire
history of the
state roots and
the hash code of
each batch
Rollup
contract
State Root:
0x1245f9
Merkle Tree
NEW State
Root: 0x1245f9
• In case of fraud, the roll-up smart
contract verifies that it is true and
cancels the batch and all
subsequent ones restoring the
correct state.
• To do this, the roll-up protocol
takes care of re-executing the
disputed transaction on layer 1
(L1) of Ethereum, determining who
is right through the calculated
state root.
• Hypothetically, just one node is
enough to make the rollup work
since entering a dispute with
fraudulent nodes would always
be the winner, and the validity of
the chain would be guaranteed.
Fraud Proof
Bond ETH

9. Popular Optimistic Rollup Platforms
• Optimistic rollups are being used by several popular blockchain platforms, including Optimism & Arbitrum.
• These platforms provide an API and SDK for developers to build and deploy smart contracts that interact with
the roll-up layer.
Native token - OP Doesn't have a native token
Features single-round fraud proofs, meaning that Layer 1
executes the whole Layer 2 transaction on-chain to verify
the state root
Uses multi-round fraud proofs making two parties (the
ones that processed the transaction and the ones that
submitted a challenge) go back and forth to narrow down
the point of dispute.
Layer 2 transaction gas is bound by Layer 1 block gas limit
Layer 1 block gas limit doesn't matter as Layer 2
transactions are never entirely executed on Layer 1
Leverages Ethereum Virtual Machine Has its own Arbitrum Virtual Machine
Optimis
m
Arbitrum
Uses a unique rollup design called Validium, which
combines optimistic rollups with a zero-knowledge
proof system for additional security and scalability.
Leverages pure Optimistic Rollup technology

10. • ZK-Rollups (Zero-Knowledge Rollups) use zero-
knowledge proofs to validate the correctness of a
batch of transactions.
• Zero-knowledge proofs allow one party to prove to
another that a statement is true without revealing
any information other than the statement's validity.
• In ZK-Rollups, a prover generates proof for a batch of
transactions that the verifier can check quickly. This
process ensures that only valid transactions are
included in the rollup, and the main chain does not
have to spend resources on validation again.
• ZK-Rollups offer fast transaction finality, high
throughput, and low gas fees.
• However, their main drawback is the complex
cryptography involved, making implementation
more challenging.
The Concept of ZK Rollups

11. What ZK Rollups Do Differently From Optimistic Rollups
To minimize transaction sizes, ZK-rollups represent account indices, which occupy less space than full
addresses. This approach allows for the utilization of 3 bytes of memory, as opposed to 20 bytes.
Merkle Root
Hash Hash
Hash Hash
Account
0x04b64e95c4f9f7…
Account
0xa7ed2936e78…
Account
0x4ecd2fce4ea3…
Account
0x7a250d5630539
Hash Hash
Ethereum Accounts (20 bytes) ZK-Rollup Accounts Index (3 bytes)
0x04b64e95c4f9f7… 0x000000
0xa7ed2936e78… 0x000001
0x4ecd2fce4ea3… 0x000002
0x7a250d5630539 0x000003

12. The Anatomy of ZK Rollups
• To implement ZK rollups, a smart contract is created on the Ethereum layer that acts as a bridge between the two layers.
• This smart contract is responsible for verifying the zk proofs submitted by the roll-up layer and updating the state of the
Ethereum blockchain accordingly.
L1 Block L1 Block L1 Block L1 Block
Tx Batch Tx Batch Tx Batch Tx Batch
Layer-1
Blockchain (e.g.
Ethereum)
Layer-2
Rollup
Users +
Transactions
Deposits Deposits Deposits Deposits
ZK Rollup Transaction Process

13. Different Components of ZK Rollups
Roll-ups Full Nodes: Even though transaction information is stored on the Ethereum network, ZK-Rollups also have
full nodes. These full nodes maintain the entire state of the blockchain and enable the use of JSON-RPC API
functionally.
Layer 2 User
Initiate transactions on
the L2 zkRollup network
Sequencer
Receive and aggregate individual
transactions from users, batching them
together in a specific order to create a
single proof.
Prover
The prover, using cryptographic
tools like zk-SNARK or zk-STARKs,
generates zero-knowledge proofs
for the transaction batches.
Rollup Light Client
The Rollup light client on
L2 receives the updated
state information from
the verifier on L1.
Verifier
Verifier is a smart contract on L1 &
checks the validity of the zk proofs.
Then it updates the contract state on L1
to reflect the latest zkRollup
transactions.
Layer 1

14. Blockchains Using ZK Rollups

15. The Limitations of ZK Rollups
Zk-rollups exhibit limited
EVM compatibility due to
their unique approach to
mapping Layer 2 (L2) wallet
addresses to Layer 1 (L1)
wallet addresses through a
single set of private keys.
Zero-Knowledge Proofs
(ZKPs) can hash
transaction data, but they
cannot independently
interact with smart
contracts.
This limitation arises from
the separate calculations
performed for each block,
as state transitions strictly
follow valid states.

16. The Promise of ZK EVM
• ZK-EVM is a virtual machine that
executes smart contracts in a way
compatible with zero-disclosure
computing. This is the key to creating an
EVM-compatible ZK Rollup.
• This essentially means that applications
can be deployed onto ZK-Rollups, with
more or less the same codebase they
use for Ethereum, preserving
composability with the EVM while not
compromising on security.
• zkEVMs are still in their initial testing
phase and will likely see significant battle
testing through 2023. Scroll, zkSync;
Polygon have all launched zkEVMs
running in testnet.
Tx Tx Tx Tx Tx Tx
Layer 1 =
Layer 2 =
zkEVM
Ethereum
zkEVM RPC nodes Batched transactions
Validity Proof 1 Transaction
User Transaction
batch
block

17. • In the EVM, a node operator can see the operations being
performed. You can “see” them in the sense that it is possible to
trace the input and output data of these operations, including
their intermediate states.
• This is possible because the EVM has an open runtime
environment; the cryptography used in the process is only there to
protect certain sections of the code (such as addresses and token
handling authorization).
• But in zkEVM environment, we can see the input data, but this is
not actually the actual data, but a series of data generated by
ZKP cryptography.
• Thus, basically, the data input is a series of data that allows the
zkEVM to verify that what we say is true, but without ever revealing
the real information that gave rise to that data.
• This input data is accompanied by execution data and a series of
token data, which the zkEVM aggregates. After grouping them, the
zkEVM has everything necessary to apply the process that will
allow it to know if the input data is correct, and ;
• If so, the zkEVM generates the status changes that indicate to the
network that the smart contract has been executed, and, In
addition to that, tests are generated that indicate that such data
and execution are correct.
Enhancing
EVM with
ZKEVM

18. Breaking Into A ZKEVM
• Polygon zkEVM is the combination of Polygon Hermez’s
evolution and technological breakthroughs derived
from work done on Polygon Zero.
• Using Vitalik’s framework for the different types of
zkEVMs, Polygon zkEVM is a Type 3 zkEVM, with the
intention to progress to a Type 2 zkEVM.
• Looking to prover architecture, Polygon zkEVM uses a
unique Proof-of-Efficiency consensus mechanism in
conjunction with a cluster of state machines which
enables greater prover efficiency.
• In terms of data availability, will use a hybrid model
(either Validium or Volition) where validity proofs are
stored on-chain, while some data is stored on or
off-chain.
• On the chain performance side, Polygon zkEVM mainnet
beta went LIVE on March 2023, and the current TVL sits
at $40M already.
Polygon ZKEVM
Synchronizer
Rollup/PoE (L1)
Rollup/PoE (L1)
zkEVM
Bridge (L2)
User
Aggregator Sequencer
User L2
RPC calls zkNodes

19. The Different Types of ZKEVM
• Can verify an environment that looks exactly like Ethereum, and
even the Ethereum Chain itself
• Can scale the Ethereum L1, and not just rollups
• Maximally easy for rollups because you can share infrastructure
(incl. execution clients)
• Takes a very long time to generate proofs
• Can verify an environment that looks exactly like Ethereum, but with
minor changes (e.g. state tree) that don't touch the application
layer
• Fully compatible with almost all Ethereum apps
• Can share most infrastructure
• Takes a long time to generate proofs
• Can verify an environment that is similar to Ethereum, but with
minor changes (eg. hash function, no precompiles) that do touch
the application layer
• Fully compatible with almost all Ethereum apps
• Can share a lot of infrastructure
• Faster to generate proofs
• Compiles contracts written in Solidity, Vyper or other high-level
langs to a specialized VM, and proves that
• Not compatible with some Ethereum apps
• Can't share a lot of infrastructure
• Fastest proof generation time, saves costs and reduces
centralization risks
• Modify the EVM only by
changing gas costs
• Makes it faster to
generate proofs
• Introduces a few
incompatibilities
1
2
3
2.5
4
Performance
Compatibility

20. The Newest Addition to zkRollup Stack: Polygon CDK
● Polygon CDK is the evolution of Supernets. It offers projects the ability to launch ZK-powered app-specific
L2 Rollups for Ethereum.
● Its highly modular and devs can tailor-make chains according to their requirements by choosing Polygon
CDK components:
CDK Component Example Section
Virtual Machine zkEVNM
Mode Validium
Data Availability DAC
Sequencer Centralized
Gas Token Custom
All chains deployed using Polygon
CDK are interoperable through a
shared ZK Bridge (LXLY) with
automatic access to the unified
liquidity of all Polygon chains, and
one-click access to the entire
liquidity of Ethereum.
New

21. Polygon
zkEVM
Polygon
PoS
C1 C2 C3 Cn
INTEROP LAYER
ETHEREUM
CDK CHAINS
New

22. Examples of Polygon CDK based App-chains
New
Canto: A neo finance project:
It has migrated to custom ZK-powered
Layer-2 designed with Polygon CDK
framework. The L2 will allow Canto to
achieve permissionless sovereignty and
shared liquidity of Polygon chains plus
Ethereum via common ZK bridges
without compromising the user's security.
Wirex: The global leader enabling
crypto payments:
It has built an app-chain focused on
handling just the payments. Wirex's initial
use cases for the CDK chain will be non-
custodial visa cards integrated with the
Account Abstraction feature. Wirex
mentioned the Polygon CDK
interoperability, unbounded scalability,
and advanced ZK proofs among their top
reasons for building with Polygon CDK.
**Capx, Aavegotchi, Gnosis pay, and Astar Network are also among the first pioneers building with Polygon CDK

23. • zkEVMs are still in their initial testing phase
and will likely see significant battle testing
through 2023. Scroll, zkSync, Polygon, and
Starknet have all launched zkEVMs running in
testnet.
• But who will win? Justin Drake, a researcher
for the Ethereum Foundation, has said,
“It turns out that in this space,
oftentimes, it is not just about
technology. Sometimes, it’s the
network effects – the culture of
the community – that is the most
important thing.”
The
Future
Ahead

24. Rollup As A Service on Zeeve
To interact with various Roll-ups & zkEVM, you'll need an API endpoint or dedicated
infrastructure.
You can do this by running your own nodes, and setting up other essential components or
you can leave the heavy lifting to Zeeve using our Rollups-as-a-service.
Zeeve Provides dedicated infrastructure support for Polygon zkEVM nodes. For app-
specific OP and ZK rollups, use OP Stack and Polygon CDK on the Zeeve platform.
Get your Rollup ready for production use with additional infrastructure components and
enterprise-grade security, 24*7 monitoring, detailed analytics, alerts & notifications.
With 27,000+ developers, 40+ large enterprises, and 6000+ nodes deployed, Zeeve is the
preferred Web3 infrastructure automation provider for enterprises & developers.

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