As new blockchains proliferate, users who want to swap assets between chains are dependent on bridges prone to problems and attacks.
Chainanalysis estimates that bridge attacks accounted for 69% of all cryptocurrency stolen in 2022, with over $2 billion siphoned from buggy cross-chain bridge platforms.
As blockchain developers increasingly recognize the problem of vulnerable bridges, some, like the Ethereum layer 2 network Starknet, are turning to “storage proofs” for help.
Storage proofs are a cryptographic method to allow users to “prove” that certain data, transactions or assets on a blockchain are true or valid, without having to rely on a third party.
“Today, you hand over money to third parties to transport over a bridge. Anyone can be lurking, waiting to ambush you and steal money,” Eli Ben-Sasson, co-founder of Starkware, the company behind the Starknet blockchain, explained in a statement. “Storage proofs will let you just press a button and more-or-less teleport liquidity from chain to chain. It’sa dramatic difference.”
According to Starknet, they will be the first network to have storage proofs natively integrated, after it goes through a security audit later this year. Currently, Starkware’s Goerli testnet has storage proofs built on it by a team called Herodotus, so project developers can experiment with the new setup.
Starkware is betting that rising demand for cross-chain transfers will soon bring storage proofs to more platforms.
How do Storage proofs work?
Storage proofs aim to enable “trustless”' cross-chain bridges, using cryptography to eliminate the need for third-party “oracles” to track assets between chains.
The method could be particularly useful for tracking assets between Ethereum and its growing community of “layer 2” chains – faster, cheaper networks that operate alongside Ethereum and rely on bridges to communicate with it and between each other.
With storage proofs, “You're basically proving mathematically – and using the integrity of math – to assert that you indeed own this asset on Ethereum,” Ben-Sasson told CoinDesk.”You don't need intermediaries, you just need the power of math.”
Ben-Sasson contends that storage proofs can, in some cases, even eliminate the need to transfer assets across different chains. Instead, users could use storage proofs to simply show on one chain that assets exist on another.
For instance, say a user has vote-bearing tokens on one blockchain, but a platform’s governance process takes place on another chain. The user can use a storage proof to show their assets on the first chain, and then vote on the second one, without having to move over the assets and pay high gas fees.
One team working on storage proofs is Herodotus, which is focused on bringing them to Ethereum’s layer 2 platforms.
Cryptographic proofs, like storage proofs, can be quite large and complex for computers to verify, making them difficult for space-constrained blockchain networks to handle. Previously, “what really made storage proofs economically unfeasible, is the fact that all the computation had to happen on the blockchain,” said Kacper Koziol, co-founder of Herodotus.
Starkware turned to zero-knowledge (ZK) cryptography to address this issue when building its storage proofs, allowing for smaller and more efficient computation.
“We can simply prove that it was computed in a valid manner and just do the verification of the computation,” Koziol said.
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