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Zendoo is the sidechain protocol designed by the Horizen team. Horizen is a private currency public chain that does not support smart contracts. The ZENDoo white paper was jointly written by the IOHK team and the Horiziz team. The main functions are:Send BT to the main blockchain, send FT to the side chain, verify the transaction is legal. A withdrawal certificate (WCert, Withdrawal Certificate) is a standardized posting. This requires at least 51% of the block producer signatures to prevent fraud.