Across on Solana

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Overview

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Architecture

• HubPool (Ethereum L1) - Central contract managing liquidity and coordinating cross-chain operations
• SVM Spoke (Solana) - Main spoke pool program handling deposits, fills, and bundle execution
• Supporting Programs - Peripheral programs for enhanced functionality

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Key Components

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Technology Stack

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Anchor Framework

• Type safety - Strongly typed Rust interfaces
• Account validation - Automatic account constraint checking
• IDL generation - Interface Definition Language for client integration
• Testing utilities - Comprehensive testing framework

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CCTP Integration

• Native USDC transfers - Burn tokens on source chain, mint on destination
• Message passing - Cross-chain communication between L1 and Solana
• Attestation service - Secure validation of cross-chain messages

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Protocol Flow

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Step-by-Step

1. Deposit - User locks tokens on Solana via deposit() instruction
2. Fill - Relayer fulfills deposit on destination chain, fronting capital
3. Bundling - Data worker aggregates fills into merkle tree bundles
4. Relay - HubPool relays root bundle to Solana via CCTP
5. Execution - Root bundle executed to process refunds and rebalances
6. Refund - Relayer claims refund using merkle proof

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Key Features

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Deposits

• Standard deposits - deposit() with auto-incrementing nonce
• Deposit now - deposit_now() with automatic quote timestamp
• Unsafe deposits - unsafe_deposit() for deterministic deposit IDs
• Message passing - Attach arbitrary data for destination contract calls

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Fills

• Fast fills - Relayers compete to fill deposits instantly
• Slow fills - Fallback mechanism using protocol reserves
• Exclusivity periods - Optional exclusive relayer windows
• Cross-chain refunds - Relayers choose refund destination chain

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Admin Functions

• Pausable - Emergency pause for deposits and fills
• Upgradeable - Cross-chain ownership via HubPool
• Bundle management - Root bundle relay and execution
• Emergency deletion - Remove invalid bundles

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Development Setup

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Prerequisites

# Install Anchor
cargo install --git https://github.com/coral-xyz/anchor avm --locked --force
avm install latest
avm use latest

# Install Solana CLI
sh -c "$(curl -sSfL https://release.solana.com/stable/install)"

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Build Programs

# Build all SVM programs (local toolchain)
yarn build

# Build with verified Docker images
yarn build-verified

# Generate TypeScript artifacts
yarn generate-svm-artifacts

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Testing

# Run all SVM tests
yarn test-svm

# Run with verified build
yarn test-svm-solana-verify

# Lint Rust code
yarn lint-rust

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Deployment

• SVM Spoke Deployment
• Multicall Handler Deployment
• Sponsored CCTP Deployment

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Network Information

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Mainnet

• Chain ID: Computed via cast to-dec $(cast shr $(cast keccak solana-mainnet) 208) 208)
• RPC: https://api.mainnet-beta.solana.com
• CCTP Domain: 5
• USDC Mint: EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v

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Devnet

• Chain ID: Computed via cast to-dec $(cast shr $(cast keccak solana-devnet) 208) 208)
• RPC: https://api.devnet.solana.com
• USDC Mint: 4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU

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Security

• Audited by OpenZeppelin - All programs undergo security audits
• Bug bounty - Report issues at [email protected]
• Security policy - See https://docs.across.to/resources/bug-bounty
• Verified builds - Reproducible builds using Solana verifiable build tools

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Resources