> ## Documentation Index > Fetch the complete documentation index at: https://docs.train.tech/llms.txt > Use this file to discover all available pages before exploring further. # Security > Key security details of the TRAIN protocol * **Homogeneous Security**: The protocol establishes consistent cryptographic security for all permissionless participants. Security attributes remain unchanged when adding new networks or Solvers. * **Battle-Tested**: The core technology of Atomic Swaps (HTLC) has been successfully used in production for the Lightning Network. * **No Pools**: No single contract holds large amounts of funds. This design choice significantly reduces the risk of being targeted by attackers. * **Immutability**: The contracts are immutable. This eliminates the risks associated with upgrades. * **Simplicity**: HTLC contracts are straightforward locking mechanisms — a single [`Train` contract](https://github.com/TrainProtocol/contracts/blob/main/chains/evm/solidity/src/Train.sol) per chain with a small surface: lock, redeem, refund. The TRAIN contracts have not yet been externally audited. The properties above describe the protocol's design; an independent audit and bug bounty are planned before the protocol is considered production-final.