Privacy-focused proof-of-work blockchain Zcash, is supposedly under a spam attack and as a result is getting clogged.
According to Jameson Lopp, chief technical officer at crypto firm Casa, the attackers are spamming the Zcash blockchain, and since June it has tripled to more than 100 GB in size.
Jameson pointed out that the blockchain has processed a large volume of transactions that aim to disrupt the network. To accomplish this, the attacker took advantage of Zcash’s “shielded transactions,” meant for privacy. The estimated cost of the attack is roughly $10 a day in transaction fees.
Simply put, the attackers misused the shielding factor of the blockchain by using Zk-snarks to implement the attack. Since Zcash protects the input output values by using Zk-snarks to hide the senders and receivers addresses.
Zcash has not had any downtime, but due to high demand on the network, nodes are finding it hard to sync with the network.
Sean Bowe, an Engineer at Zcash tweeted “At this point, there only seems to be two problems with the spam: it’s bloating the chain size, and it’s making it harder for wallets to sync.”
The motive for this attack has not been determined yet, however the community has formulated a lot of theories.