The blockchain landscape has expanded into a multi-chain environment driven by DeFi protocols, NFT ecosystems, and on-chain applications. Ethereum and Solana stand out with their distinct token standards ERC‑20 and SPL powering millions of tokens across separate ecosystems.
However, this separation creates token silos. ERC‑20 tokens can’t interact natively with Solana’s SPL ecosystem, limiting liquidity and interoperability. The result is fragmented user experiences and technical friction for developers building cross-chain applications.
Cross‑chain token standard adapters are designed to address this challenge. These adapters act as protocol-level bridges that synchronize token states across incompatible chains. By supporting mint and burn functions on both ends, they unlock secure, scalable token transfers without relying on centralized custodians or basic wrapping.
Understanding the Standards
1. ERC‑20 & Its Evolution
ERC‑20 is Ethereum’s foundational token standard. It defines functions for transferring tokens, approving spenders, and checking balances. While widely adopted, ERC‑20 lacks native cross-chain functionality—there’s no standardized way to mint or burn tokens across multiple blockchains.
To close this gap, ERC‑7802 was introduced. Proposed by contributors from Uniswap and Optimism, ERC‑7802 extends ERC‑20 by adding two simple yet powerful functions: crosschainMint and crosschainBurn. These functions allow bridges to mint or burn tokens on target chains, enabling native cross-chain interoperability without modifying existing bridge architectures.
Key characteristics of ERC‑7802:
- Maintains full backward compatibility with ERC‑20
- Bridge-agnostic implementation
- Supports ERC‑165 interface detection for improved interoperability
- Provides a standardized event schema to simplify bridge logic
By standardizing these operations, ERC‑7802 enables smoother interactions between chains while preserving the security guarantees of the underlying networks.
2. SPL & Token‑2022
Solana’s SPL token standard was developed to support high-throughput, low-cost token operations. Unlike ERC‑20, SPL is governed by a centralized token program that handles both fungible and non-fungible tokens using a unified interface.
Token‑2022, Solana’s extended token program, enhances SPL with modular features tailored for advanced use cases. These include:
- Transfer fees: Built-in mechanisms for fee extraction on each transfer
- Transfer hooks: Support for executing program logic during token movements
- Non-transferable tokens: Useful for certifications, badges, or gated access
- Interest-bearing tokens: Native support for yield accrual
- Mint control: Dynamic authority delegation for mint and burn functions
Token2022 is backward-compatible with standard SPL tokens but enables more programmable behavior, making it well-suited for cross-chain asset management, compliance logic, and tokenized financial instruments.
Standards in Action: ERC‑7802 & xERC‑20 Ecosystem
ERC‑7802: A Bridge‑Agnostic Power Move
ERC‑7802, born from a partnership between Optimism and Uniswap, is revolutionizing how ERC‑20 tokens cross chains. Think of it like adding a universal translator to your crypto tokens—it doesn’t matter which bridge you use, it just works. With crosschainMint and crosschainBurn, tokens can be burned on one chain and minted on another without ever losing total supply.
What’s slick is it’s fully ERC‑165 compatible and doesn’t interfere with normal ERC‑20 behavior—so existing tokens can be upgraded without breaking things.
ASTR on Astar: Superchain Interoperability in Action
Meet ASTR, Astar Network’s native token, now running on ERC‑7802 with Chainlink CCIP for the first time ever. It’s not just theory—ASTR works across Polkadot-based Soneium and Ethereum-compatible Superchains. What does that mean in real life? Two-click transfers, sub-second liquidity movement, and a unified security model. As Zain Bacchus from OP Labs puts it, users get “frictionless movement” with no token duplicates or sludge clogging the pipes.
xERC‑20 & Lockbox: Wrapping Tokens the Smart Way
Loved your ERC‑20 token but want cross‑chain action? Enter xERC‑20. Think of Lockbox as a vault: you deposit your original token and receive a wrapped version—xTOKEN. When it’s time, you just bridge with xTOKEN, and on the other side, your original asset is safely unwrapped. This approach is bridge-agnostic, liquidity-efficient, and keeps control in the token issuer’s hands.
Why Adapters Are Essential
Legacy Bridges Still Live in ERC‑20 Land
Despite the buzz around new token standards, protocols like Chainlink’s CCIP are still built for classic ERC‑20s. These bridges expect mintable and burnable tokens, so anything else falls flat.
Adapter Magic: Wrapping the New for the Old
Adapters act like interpreters. They wrap modern ERC‑7802 tokens so they can speak to old-school bridges and unwrap them on the other side. That seamless wrap/unwarp dance transforms modern into legacy and back again.
Optimism’s Superchain Guidance
The Optimism docs are clear: Superchain tokens “implement the IERC7802 interface, deploy at the same address on every chain, and allow the SuperchainTokenBridge to call crosschainMint/Burn”. Adapters are the bridge glue, making sure modern tokens can play nicely with Superchain policies.
Deep Dive: Adapter Design & Workflow
Core Functions — Flowing Like Water
- Approval – User gives adapter permission.
- Lock/Wrap – Adapter locks the original token; wraps it if needed.
- Send – Adapter pushes the wrapped token through the bridge.
- Mint/Burn – On the other side, tokens are minted or burned.
- Unwrap/Release – Recipient gets the original token unwrapped and ready to use.
State Tracking — Guarding Against Mishaps
Adapters keep an eye on every transfer—block numbers, nonce counters, sender info—to avoid replay attacks, double-minting, or stale transactions. It’s like having a flight-tracking app: no duplicates, no lost baggage.
Payload Support — More Than Just Tokens
Adapters can attach extra info like memo fields, timestamps, or routing metadata. That means your transfer doesn’t just move tokens—it carries reminders, routing notes, or compliance flags right where they’re needed.
Looking to build a cross‑chain bridge for your token project?
Cross‑Chain Flow: ERC‑20 ↔ SPL
Source (Ethereum → Solana): Initiating the Transfer
On Ethereum, the user initiates the transfer by approving the cross‑chain adapter to manage their ERC‑20 tokens. The adapter wraps the ERC‑20 into a compatible format, typically an xERC‑20 variant, that supports cross‑chain communication protocols like CCIP or LayerZero OFT.
Message Relay and Asset Handling on Solana
Once the token is wrapped, a secure bridge relays the transaction message to Solana. The Solana-side adapter interprets the message and executes the logic—either minting a new SPL token using Token‑2022 standards or unlocking a pre-minted token held in escrow. This ensures the user receives the corresponding value on Solana in the appropriate format.
Reverse Flow (Solana → Ethereum)
In the opposite direction, the adapter on Solana burns or locks the SPL tokens. A structured message is sent back to Ethereum, where the corresponding ERC‑20 is either unwrapped or freshly minted. This ensures value remains consistent while enabling token mobility between the chains.
Security Considerations: Mitigating Cross‑Chain Risks
Cross‑chain operations involve technical complexity and risk. Several known vulnerabilities require structured countermeasures to ensure safe transfers.
Key Attack Vectors
- Replay Attacks: Attackers may attempt to reuse messages to trigger unintended transactions.
- Oracle Manipulation: Malicious or faulty oracles can feed incorrect data, leading to incorrect asset minting or loss.
- State Integrity Breaches: Broken nonce validation or misconfigured contracts can allow duplicate transfers or state inconsistencies.
Recommended Safeguards
- Pausable Smart Contracts: Emergency halts can protect funds during unexpected behavior.
- Multi-Signature Governance: Sensitive actions (like minting rights) require approval from multiple parties.
- Nonce and Payload Validation: Strong message schema validation prevents duplication, spoofing, and tampering.
Proven Audit Strategies
Leading research such as SoK (Systematization of Knowledge) and Xscope outlines formal testing frameworks, including:
- Fuzzing cross-chain message inputs
- Verifying token accounting accuracy post-transfer
- Simulating oracle failures and race conditions
Real‑World Implementations & Metrics
Astar Network & ERC‑7802 Adoption
Astar integrated ERC‑7802 with Chainlink CCIP to achieve true multi-chain deployment. Using these standards, ASTR tokens can move between Ethereum, Optimism, and Polkadot seamlessly. The adapter layer ensures standardization while preserving token behavior.
Wormhole Bridge: ERC‑20 ↔ SPL in Production
Wormhole employs a lock-and-mint model to handle transfers between Ethereum and Solana. Tokens are locked on the source chain, and equivalent assets are minted on the destination. The approach is well-documented and widely adopted across DeFi protocols using SPL.
Performance Benchmarks
- Solana: ~65,000 transactions per second, 400 ms average block time, and transaction fees under $0.01
- Ethereum: ~15 TPS on the base layer, with gas fees ranging from $3 to $10 depending on network congestion
Conclusion
A cross-chain token standard adapter acts as the critical infrastructure for seamless interoperability between ecosystems like Ethereum and Solana. By leveraging standards such as ERC‑7802 and Token‑2022, these adapters enable secure, traceable, and efficient token movement across chains—unlocking liquidity, expanding use cases, and supporting composable DeFi. As multi-chain architecture becomes the norm, businesses and developers must adopt robust bridging mechanisms to stay competitive. Blockchain App Factory provides cross-chain bridge development solutions that are engineered for performance, security, and compliance—empowering projects to thrive in an interconnected blockchain future.
