Blockchain bridges, also known as cross-chain bridges, are designed to connect different blockchain networks and enable the transfer of assets between them. However, developers must address several fundamental security concerns to ensure these bridges are safe and secure.
One primary concern is the potential for hacking or theft of assets. As assets are transferred across different blockchain networks, they can become vulnerable to attacks from malicious actors. This can result in the loss of assets and damage the blockchain network’s reputation. Therefore, it is essential to implement robust security measures such as encryption and multi-signature transactions to mitigate this risk.
By the end of 2022, over $2 billion was lost in cross-chain bridge hacks, showing the severity of bridge attacks in the industry. Roughly $190 million was stolen from the Nomad bridge in August 2022 before whitehat hackers returned $9 million worth of funds to users.
Axie Infinity’s Ronin bridge lost over $615 million when the protocol was hacked in March 2022. Additionally, Binance recently assisted in recovering $3 million from the hacked Harmony bridge.
Another concern is the risk of smart contract bugs. For example, blockchain bridges often rely on smart contracts to facilitate the transfer of assets between networks. However, a bug in the smart contract could result in unintended consequences, such as the loss of assets. To address this risk, it is essential to test and audit smart contracts thoroughly before deployment.
While blockchain bridges have the potential to enhance the interoperability of different blockchain networks significantly, it is crucial to be aware of and address the fundamental security concerns to ensure the safe and secure operation of these bridges.
There are two main types of cross-chain bridges, trusted and trustless bridges.
Trusted bridges are cross-chain protocols that take custody of a user’s tokens during the bridging process. These protocols are also known as custodial bridges. When a user wants to bridge from one blockchain to another, the tokens are locked into the bridge and are under the responsibility of the organization behind the bridge.
Since users need to give up crypto custody to a centralized entity when using trusted bridges, it may be easier for hackers to compromise the protocol. Again, this is because it is a central point of control that malicious actors can target. The Avalanche Bridge on the Avalanche (AVAX) is a popular example of a trusted bridge. The Ava Labs organization controls the tokens locked into the protocol.
Trustless bridges are decentralized bridging protocols that use smart contracts instead of a centralized authority to manage the locked tokens and complete cross-chain transfers. As a result, trustless bridges give users more control over their tokens and there is no central point of failure.
However, trustless bridges are imperfect and if there are vulnerabilities in the smart contract code, the bridge can be compromised by a malicious actor.
Trustless bridges are considered safer than trusted ones despite the potential for flaws in the code.
One example of a trustless bridging protocol is Pendulum, a decentralized network of smart contracts that connects fiat railways to the environment of decentralized finance (DeFi). The bridge increases fiat liquidity in the DeFi industry by linking compliant currency-pegged tokens from major blockchain networks into different ecosystems within the decentralized finance space.
What blockchain platforms can do to prevent further exploits
Blockchain platforms can learn from hacks of cross-chain bridges by analyzing the exploited vulnerabilities and implementing measures to prevent similar attacks in the future. One approach is to adopt trustless or minimal trust operations in the construction of the bridge architecture.
Trustless or minimal trust operations refer to designs that do not rely on a centralized authority or intermediary to facilitate the transfer of assets between different chains. Instead, these designs use smart contracts and cryptographic techniques to ensure the security and integrity of the transferred assets.
One example of a trustless cross-chain bridge is the atomic swap, which allows for the exchange of assets between different chains without needing a centralized intermediary. The process works by using a smart contract that holds the assets in escrow and releases them to the correct party once the terms of the exchange are met.
Another example is using a sidechain, a separate chain pegged to the main chain. This process allows for assets to be transferred to the sidechain, where they can be traded or processed with a different set of rules and then moved back to the mainchain in a secure and trustless manner.
By implementing trustless or minimal trust operations, blockchain platforms can improve the security of their cross-chain bridges and make them less vulnerable to attacks.