Obscuro and Ethereum Interaction

Obscuro is a confidential extension to Ethereum, and thus assets have to move freely between the two networks.

All sidechains and L2 solutions have developed solutions to the mismatches between the different models of the two networks, and typically there is a bridge contract that safeguards assets. The difference between sidechains and L2 solutions is that mismatches are more significant for sidechains because they have their own finality and security mechanisms, and thus the bridge logic is either very complex or centralised.

DepositsPermalink

The user deposits supported ERC tokens into the well-known address of the Bridge contract, and once the transaction is successfully added to a block, the Obscuro-enabled wallet automatically creates an L2 transaction, including proof of the L1 transaction. The exact amount is credited with wrapped tokens on the user’s account on Obscuro.

The fact that the finality of L1 transactions is probabilistic makes crediting the L2 account not straightforward. Most solutions solve this problem by waiting for a confirmation period before crediting the account. Obscuro takes a different approach and introduces a dependency mechanism between the L2 rollup and the L1 blocks.

The rule is that the L2 rollup that includes the transaction that credits the Obscuro account has a hard dependency on an L1 block, and the Bridge contract enforces that it is one of the ancestors of the current block. If the L1 deposit transaction is no longer in the canonical L1 chain, it automatically invalidates the rollup that contains the L2 deposit transaction, and the L1 deposit will only be recognised as the basis for an L2 rollup credit transaction when it has been included in the canonical L1 chain.