Polygon (polygon.technology) has introduced CDK Besu, an infrastructure solution designed to help banks, financial institutions, and enterprise consortia connect private blockchains to other networks through the company's Agglayer interoperability platform. The system combines Hyperledger Besu, an open-source Ethereum client widely used in enterprise blockchain infrastructure, with zero-knowledge cryptographic proofs, enabling cross-chain asset transfers while keeping private transaction data off the public Ethereum blockchain.

With CDK Besu, institutions can maintain control over network participants, validators, and transaction privacy while still accessing liquidity across connected blockchains. The solution is production-ready on Ethereum mainnet, and organizations already operating Hyperledger Besu networks can connect to Agglayer without building an entirely new blockchain. This gives institutions a way to preserve existing permissioned infrastructure while adding connections to networks that support broader asset liquidity.

Under the new configuration, institutions can establish permissioned networks in which only authorized validators approve transactions and participate in network operations. Previously, connecting private Besu-based networks to external blockchains often required custom integrations and bridges that depended on designated signers to authorize asset transfers. Polygon's setup incorporates the Agglayer connection from the beginning, reducing the need for separately developed interoperability infrastructure.

QBFT Consensus Supports Controlled Network Participation

CDK Besu uses the Quorum Byzantine Fault Tolerance (QBFT) consensus mechanism, which allows a predefined group of validators to approve blocks and achieve immediate finality once consensus is reached. The architecture is intended for banks, financial infrastructure providers, and consortia that require strict control over network access.

Institutions can operate their own validators and take part in decisions concerning the admission or removal of network members. The system can also require approvals from a minimum number of consortium participants for certain operations involving Agglayer, an arrangement to prevent any single institution from unilaterally authorizing actions that affect shared network operations.

Private transaction information remains within the institution's own infrastructure rather than being published on Ethereum. The public blockchain is instead used to settle cross-chain transfers after the required cryptographic proofs have been verified. This separation is intended to help financial institutions combine confidentiality with interoperability, addressing a key challenge in deploying blockchain technology for regulated financial services.

Zero-Knowledge Proofs Secure Cross-Chain Asset Transfers

A central component of CDK Besu is Polygon's pessimistic proofs system, which verifies the balances associated with transfers between connected networks. The mechanism is designed to ensure that a blockchain cannot withdraw more assets through the interoperability system than it has received, containing the financial impact of a compromised network by preventing it from withdrawing assets belonging to other connected blockchains beyond its verified balance.

Proofs are generated through the Succinct Prover Network and verified before the corresponding transfers settle on Ethereum. This approach provides cryptographic verification of cross-chain accounting without requiring private transaction details to be disclosed publicly.

The system does not, however, individually verify every transaction executed within each private blockchain. Institutions that require proofs covering transaction execution can consider another Polygon CDK configuration based on the OP Stack. The distinction allows organizations to choose infrastructure according to their privacy, verification, and operational requirements.

Tokenized Deposits Could Move Across Financial Networks

Agglayer is designed to let institutions transfer assets between connected blockchains, including public networks that provide liquidity for stablecoins and tokenized financial products. The infrastructure maintains a single canonical version of each asset across participating networks, aiming to reduce the fragmentation and duplication risks associated with separate bridges creating competing representations of the same token.

Polygon announced the launch in an X post on October 19, 2026:

Introducing CDK Besu, now live in Polygon CDK. A private Besu chain no longer has to be an island. Launch a private chain with Polygon Open Money Stack, connected to other chains and their liquidity, upgraded with Agglayer's security.

— Polygon (@0xPolygon) October 19, 2026

One example outlined in the announcement involves a bank issuing tokenized deposits on its private blockchain and enabling customers to transfer them to another network to purchase shares in a tokenized money market fund. Without direct interoperability, the process might require converting deposits into traditional money, transferring the funds through banking channels, and acquiring the investment on the destination network. With CDK Besu and Agglayer, the asset could move directly between connected blockchains, potentially reducing intermediate steps and operational friction.

Polygon has also stated that institutions will not need to share revenue generated by activity on their networks with the company, a policy that could provide additional flexibility for organizations developing commercial blockchain services.

Existing Besu Networks Can Connect to Agglayer

Polygon has published deployment instructions and open-source components for implementing CDK Besu, alongside test and development environments. The ability to connect existing Besu networks is particularly relevant for institutions that have already invested in permissioned blockchain infrastructure. Rather than replacing those systems, organizations can extend their connectivity to other networks while retaining control over internal operations. In practice, institutions evaluating the system will need to assess how the validator model, proof requirements, and Ethereum settlement process fit their existing governance and compliance arrangements.

The technology's broader adoption will depend on institutional demand, integration requirements, and regulatory considerations. Nevertheless, CDK Besu represents an effort to bridge private enterprise blockchains and public digital asset markets without requiring financial institutions to sacrifice transaction confidentiality or network governance.

Source: CoinTrust