Zcash Used Chernobyl Radioactive Waste

Radioactive waste used to ensure the secrecy of Zcash network
30 January 2018   1060

The developers of anonymous cryptocurrency Zcash used radioactive waste from Chernobyl to ensure the secrecy of their network, CoinDesk reports.

As reported on the ZCash Foundation website, any calculation to create and confirm zero-disclosure evidence (zk-SNARKs) used in ZCash and a number of other anonymous crypto-currencies requires the specification of public parameters. If someone can unravel the algorithm for setting these parameters, he can create his own false evidence.

It is for this reason that ZCash developers conduct so-called Powers of Tau ceremonies, during which the most trusted persons, using complex procedures, set the initial parameters. This time, as an alternative to the generation of random parameters, radioactive waste was used.

According to the developer Andy Miller, the source of low-frequency radiation from gamma and beta particles was graphite, extracted from the reactor core of the Chernobyl nuclear power plant. The Geiger counter connected to the number generator helped to translate the radiation into numerical values, which were integrated into the code.

The entropy source was a hardware-based random number generator utilizing a Geiger tube and a radioactive source, constructed and programmed by Ryan Pierce. [The graphite emitted very low levels of radiation], falling substantially below all thresholds that might restrict its transportation by air, and posting no health risk.

Andrew Miller


To ensure the impossibility of interference in the procedure of third parties, it was conducted at an altitude of 900 m above sea level in a private aircraft over the states of Illinois and Wisconsin. Also, developers, as a rule, destroy all computers or, at least, the software used to create the code.

In theory, this procedure allowed developers to get an absolutely random and private code snippet, which they can use to further improve Zcash.

Zcash Privacy to Have Vulnerability, Researchers Say

Four researchers from University College London have identified patterns in certain kinds of Zcash transactions that weaken their anonymity
10 May 2018   828

George Kappos, Haaroon Yousaf, Mary Maller and Sarah Meiklejohn found that when coins move from "unshielded" to "shielded" and back to "unshielded" addresses, they lose much of the anonymity that zcash users expect. The team noted that "relatively simple heuristics ... reduce the size of the overall anonymity set by 69.1 percent." This is reported by Coindesk.

Note that ZCash, positioned as one of the most promising and respected confidential crypto currency, offers two types of addresses: "T-addresses" are transparent and unprotected, transactions and balances are publicly available. In turn, "Z-addresses" are protected and invisible to the general public.

Thus, transfers from one unprotected address to another are completely public, whereas transactions between protected addresses are almost anonymous (only time marks and commissions related to mining are displayed).

At the same time, researchers found that transactions involving different types of addresses are much less confidential. So, if you want, you can get information even about Z-addresses, the report says. 

Our heuristics would have been significantly less effective if the founders interacting with the pool behaved in a less regular fashion. In particular, by always withdrawing the same amount in the same time intervals, it became possible to distinguish founders withdrawing funds from other users.

The University College London Research Team

These transactions (as well as similar ones carried out by the miners) are caused by the necessity of holding ZCash coins through secure Z-address pools before they can be used for other operations.

Researchers also noted that they told the founders about the problems found before the publication of the report, which has already led to a change of patterns. In turn, the founder of ZCash Zooko Wilcox and marketing director Josh Swihart in the reciprocal message congratulated the university team.

It is valuable to understand how much privacy is lost when using shielded addresses as a pass-through mechanism, but using it in that way is not recommended. Instead, store your Zcash in a shielded address.

Zooko Wilcox and Josh Swihart


Wilcox and Swihart said that planned upgrades to the zcash protocol would lessen the risks to anonymity identified in the reasearch.