“ZenCash is a “proof of work” (PoW) cryptocurrency based on the Equihash mining algorithm. On May 31, the ZenCash network experienced a 51 percent attack, meaning a single party gains control of the majority (51 percent) of the hash rate, enabling them to reorganize the blockchain and reverse blocks. According to a statement from the development team, this attacker was able to double spend two large transactions worth more than $550,000 at current rates.”
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