Noted whistleblower Edward Snowden has come out in support of the privacy-oriented cryptocurrency zcash, calling it the “most interesting alternative” to bitcoin.

Writing in response to a tweet from technologist Mason Borda which read: “Zcash is the only altcoin (that i know of) designed and built by professional and academic cryptographers. Hard to ignore,” Snowden replied, “Agree.”

He continued:

“Zcash’s privacy tech makes it the most interesting Bitcoin alternative. Bitcoin is great, but “if it’s not private, it’s not safe.'”

Snowden is a prominent privacy advocate and is most well known for his massive leak of classified NSA documents in 2013. Asked for his thoughts on monero, a competing private currency, Snowden said it was “amateur crypto” and pointed to traceability issues within the tech.

Snowden said that such design errors could put fellow whistleblowers at risk, stating: “Mistakes happen and have huge consequences for people like me.”

The statements fed into the existing rivalry between the competing currencies. In the resulting flood of Twitter responses, Monero developer Richard Spagni strongly defended his project’s technology, while the creator of litecoin, Charlie Lee, stated: “I own Monero but not Zcash”.

Zcash and monero are both geared towards providing privacy for their users, but use different tools to – arguably it seems – achieve the same end result.

While zcash is based on a cryptographic operation called zk-snarks, monero works by obfuscating information with ring signatures and stealth addresses.

Disclosure: CoinDesk is a subsidiary of Digital Currency Group, which has an ownership stake in Zcash Company, the for-profit entity supporting zcash’s development.

Snowden posters image via Shutterstock