Durin & CCIP

Durin is the original version of CCIP-Read. It provides a way for Ethereum L1 contracts to specify offchain data lookup.

• EIP: https://eips.ethereum.org/EIPS/eip-3668
• Discussion: https://ethereum-magicians.org/t/durin-secure-offchain-data-retrieval/6728
• Examples:
  • @makoto: https://github.com/makoto/durin-examples/tree/master/examples/template
  • ccip-read: https://github.com/smartcontractkit/ccip-read

Rough diagram of core components:

Proofs

The trickiest part of the equation, proofs have the following properties:

• implementation dependant
• can't be faked by an attacker
• need to be validated on L1

An example from CCIP-Read repository using Optimism as the data source:

1. The gateway:
   1. gets the state batch header
   2. constructs a Merkle proof
   3. gets the L2 contract address and slot that contains the required data
   4. gets a proof from Optimism rollup (via eth_getProof) using address and slot
   5. returns the state, proof, and wintess
2. The client passes on the information to the L1 function functionNameWithProof
3. The L1 function:
   1. verifies the proof
   2. returns the data to the user