Stellar Launches X-Ray Privacy Upgrade on Mainnet to Power Next-Gen ZK Apps

• The X-Ray upgrade by Stellar is already on mainnet and includes native BN254 operations to verify on-chain zk-SNARKs.
• CAP-0075 adds Soroban host functions exposing Poseidon and Poseidon2 permutation primitives for ZK-friendly hashing.

Stellar has deployed the X-Ray protocol upgrade, Protocol 25, on its mainnet and is expected to add new cryptographic building blocks to its architecture to enable zero-knowledge applications on Soroban smart contracts. The upgrade was scheduled for a network vote on January 22 at 17:00 UTC, after which it took effect immediately once validators approved the change.

Network monitoring pages now list the Stellar public network as running Protocol 25, marking the transition from earlier protocol versions. With Protocol 25, developers can verify modern ZK proofs more efficiently on-chain. It also reduces the need to implement specialized cryptography directly inside smart contracts, according to SDF documentation.

The upgrade follows earlier testing steps, including a Testnet vote on January 7, 2026, and is positioned as a foundational layer for privacy-focused development. At Meridian 2025, SDF Chief Product Officer Tomer Weller outlined a longer-term strategy for configurable, compliance-forward privacy on Stellar that relies on native cryptographic capabilities.

X-Ray centers on the BN254 pairing-friendly elliptic curve and the Poseidon family of hash functions. Together, they are intended to support the smooth migration of existing ZK applications, more efficient proof systems, and lower costs for ZK-based contracts.

Recently, CNF reported that Stellar partnered with MIT and several blockchain projects, including Chainlink, Wormhole, and Canton, to support a new interoperability whitepaper under the Interoperability Standards Organization for Digital Assets.

Stellar Expands Soroban’s ZK Toolkit

The BN254 upgrade ships with CAP-0074, which adds new Soroban host functions for core elliptic-curve operations: point addition, scalar multiplication, and multi-pairing checks. These are the exact primitives zk-SNARK verifiers rely on, and they mirror Ethereum’s EIP-196 and EIP-197 precompiles. The goal is straightforward: make EVM-based apps and crypto libraries easier to port to Soroban with fewer custom workarounds.

For hashing, CAP-0075 introduces host functions that expose the core permutation primitives behind Poseidon and Poseidon2. Because these hashes are designed for ZK circuits, they typically require fewer constraints than traditional hashes when used inside proofs, which can reduce proving costs. 

The availability of native primitives also supports consistent hash behavior between on-chain verification and off-chain proving.

Through the addition of the BN254 to the BLS12-381 feature, applications using Soroban can choose the curve that fits their integration or proof system requirements. This approach will simplify migration paths for established ZK applications.

Stellar (XLM) is at press time trading at $0.2096 with a market cap of $6.79 billion and a 24-hour trading volume of approximately $111.7 million.