spv – Is the competition interval actually crucial for cross-chain transactions in 2-way-peg sidechains?
In keeping with the primary sidechain article (Hyperlink), the cross chain transaction course of will be briefly describe as follows:
Alice has a pockets on sidechain S1. She needs to ship some cash to sidechain S2. So she makes a transaction containing some cash, ship it to a sure locked-output on S1.
Look ahead to affirmation interval to finish.
After the transaction is confirmed, she submits a SPV proof to S2.
Once more, she has to attend for a contest interval.
After the competition interval ends, an equal quantity of cash is created and despatched to her pockets on S2.
I assume that each the sidechains are safe, in any other case there’s not a lot left to debate. If they’re safe, then after the affirmation interval in step 2 above, the sidechain S2 already is aware of that the transaction is confirmed on sidechain S1. For instance, if Alice purchases one thing utilizing Bitcoins, step 3 is the place she will be able to get the product she bought from a standard retailer.
In my view, after the affirmation interval, the transaction is already in a steady a part of S1. Thus, there can’t be any legitimate SPV proof that contradicts the SPV proof Alice despatched, except S1 doesn’t fulfill the persistence property.
Therfore, I want to ask, why is the competition interval crucial? Is there one thing I’m lacking in my argument? Thanks.