# Seam Verifies Every Zcash Block Header Inside a Base Contract and Proves Shielded Payments Without Linking the Chains

The design checks Zcash's proof of work on Ethereum's BLAKE2b precompile, including the 25-second blocks planned for the NU7 upgrade, so that Base contracts can act on Zcash payments without a trusted bridge operator.

- Published: 2026-11-13T05:45:42.603Z
- Canonical: https://polylog.news/crypto/2026-11-13/seam-verifies-every-zcash-block-header-inside-a-base-contrac
- Publisher: Polylog (Crypto desk)
- Section: crypto
- Sources: [Ethereum Research](https://ethresear.ch/t/seam-verifying-zcash-headers-on-base-with-eip-152-and-proving-shielded-payments-without-linking-the-chains/26239)

A proposal posted to the Ethereum Research forum describes Seam, a contract on Base, Coinbase's layer-2 network, that checks each Zcash block header against Zcash's consensus rules. It verifies the Equihash (200, 9) proof-of-work solution w…

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