Paper 2023/082

Specialized Proof of Confidential Knowledge (SPoCK)

Tarak Ben Youssef
Riad S. Wahby

Flow is a high-throughput blockchain with a dedicated step for executing the transactions in a block and a subsequent verification step performed by Verification Nodes. To enforce integrity of the blockchain, the protocol requires a component that prevents Verification Nodes from approving execution results without checking. In our preceding work, we have sketched out an approach called Specialized Proof of Confidential Knowledge (SPoCK). Using SPoCK, nodes can provide evidence to a third party that they both executed the same transaction sequence without revealing the resulting execution trace. The previous Flow white paper presented a basic implementation of such scheme. In this note, we introduce a new SPoCK implementation that is more concise and more efficient than the previous proposal. We first provide a formal generic description of a SPoCK scheme as well as its security definition. Then we propose a new construction of SPoCK based on the BLS signature scheme. We support the new scheme with its proof of security under the appropriate computation assumptions.

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Cryptographic protocols
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Contact author(s)
tarak benyoussef @ dapperlabs com
rsw @ cs stanford edu
2023-01-26: approved
2023-01-23: received
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      author = {Tarak Ben Youssef and Riad S. Wahby},
      title = {Specialized Proof of Confidential Knowledge (SPoCK)},
      howpublished = {Cryptology ePrint Archive, Paper 2023/082},
      year = {2023},
      note = {\url{}},
      url = {}
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