What is the ultimate ideal of cross-chain technology? The answer is "Trustless" — users do not rely on any third party and can still ensure asset security. It sounds simple, but actually implementing it is extremely difficult.

Currently, the industry is exploring three main approaches:

**The first is light client / relay verification.** Deploy a light client of the source chain on the target chain, with relayers continuously transmitting block header information, and verify to ensure transaction authenticity. This approach is the most decentralized, but it is highly complex to implement and requires substantial infrastructure support.

**The second is Multi-Party Computation and Threshold Signatures (TSS).** A network of distributed nodes jointly manages the keys, and asset releases require signatures from the majority of nodes. This solution strikes a good balance between decentralization and operational efficiency and is the preferred choice for many projects currently.

**The third is Optimistic Verification.** This approach borrows from Layer 2's Optimistic Rollup, initially assuming cross-chain transactions are valid, then leaving a challenge period for the community to dispute, and using fraud proofs to ensure security. The benefits are low cost and fast speed, but it requires a sufficiently active ecosystem.

Different technical routes correspond to different trade-offs. In the "Security Triangle" (decentralization, security, efficiency), each has its own position. Choosing which path to take directly affects a project's long-term competitiveness and risk tolerance. For users seeking a deeper understanding, grasping this technical logic is essential to accurately assess the prospects of cross-chain infrastructure.