Mandatory Software Upgrade: Download ZEN 2.0.21 NOW

ZEN 2.0.21 replaces the current version, ZEN 2.0.20, which is set to deprecate (no longer run). The focus of this version is general maintenance and includes the fixes and features listed below.

Please update your ZEN software before the 2nd of June.

ZEN 2.0.21, Sphere by Horizen 1.2.7, and Swing wallet updates are available now on our GitHub or through the APT repository.

ZEN 2.0.21 Updates

• •  Fix for upstream CVE-2020-8806
    • Changes how nodes enforce timestamp requirements on block headers. Miners and pools should make sure the blocks they generate conform to the new stricter timestamp requirements. Getblocktemplate will always provide a valid timestamp. For details see https://electriccoin.co/blog/new-releases-2-1-1-and-hotfix-2-1-1-1/
    • This change will be deployed by soft-fork on mainnet block 740600 (v2.0.20 mainnet deprecation +8d) and on testnet block 651100 (v2.0.20 mainnet deprecation -7d), pools have the opportunity to test on testnet in the 2 weeks leading up to the mainnet soft-fork.
  •  Removal of time adjustment
    • Prior to v2.0.21, zend would adjust the local time that it used by up to 70 minutes, according to a median of the times sent by the first 200 peers to connect to it. This mechanism was inherently insecure since an adversary making multiple connections to the node could effectively control its time within that +/- 70 minute window (this is called a “timejacking attack”). In the v2.0.21 release, in addition to other mitigations for timejacking attacks, as a simplification, the time adjustment code has now been completely removed. Node operators should instead simply ensure that local time is set reasonably accurately. If it appears that the node has a significantly different time than its peers, a warning will still be logged and indicated on the metrics screen if enabled.
  •  Introduce new optional parameter to zen-cli z_sendmany
    • The optional parameter “sendChangeToSource” has been introduced. 

      (boolean, optional, default = false) If true and fromaddress is a taddress return the change to it

  • The deprecation/release cycle has been changed to 26 weeks/biannually
    • next deprecation to occur 2 weeks before the next block reward halving

What happens if you do not upgrade before the 2nd of June?

• Exchanges and Partners: you will not be able to access your funds until you upgrade to the latest version.
• Pool operators: ZEND will not work and thus you will not be able to mine ZEN until you upgrade to ZEN 2.0.21.
• Node operators: ZEND will not work and thus you will not be eligible to earn ZEN until you upgrade to ZEN 2.0.21.
• Full node wallet users (Swing wallet, Sphere by Horizen): you will not be able to access your funds until you upgrade to the latest wallet version.

Download ZEN 2.0.21 NOW

Always download software from Horizen official channels. Read our Security Guidelines to keep your ZEN safe

Please let us know if you have any questions. Thank you for your continued support! As always, be sure to follow us on Twitter, Facebook, and Discord for the latest updates.