I'm building a system that allows a user to "claim" a ERC1155 NFT on Polygon/Matic if they own a certain ERC1155 NFT on the root network (ethereum). My current solution works off-chain, by authenticating root-network ownership via a website signature request and then transferring the token on Matic if the signature passes.

Since it is off-chain, there are race conditions in validating ownership. Is there an on-chain way to validate root-network NFT ownership from a Polygon/Matic contract? Any solution without race conditions is on the table.

  • Good question :-) I think the best place to ask would be in their Discord - their support team are more likely to know the answer. (Link at the bottom of page -> polygon.technology) May 17, 2021 at 9:49
  • Thanks! I did actually but unfortunately their discord is probably 100 questions for every 1 answer. I'll ping again and see if I get a response. May 17, 2021 at 17:25

1 Answer 1


In trying to solve this problem I have come across the "polygon state sync" (thank you 0xTomoyo :-)) https://docs.polygon.technology/docs/contribute/state-sync/state-sync/

It looks like this requires the addition of an emitter on the ETH contract side, but should do the trick.

Also, it looks like chainlink is heavily developing solutions for this problem with their cross chain interoperability protocol (CCIP) https://blog.chain.link/introducing-the-cross-chain-interoperability-protocol-ccip/

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