My mistake. How ironic. Everything depends upon the red wheelbarrow. Here's that link without the trailing ": https://news.ycombinator.com/item?id=19181362

> My main problem with blockchain is the excessive energy consumption of PoW. I know there are PoS efforts, but they seem problematical.

One report said that 78% of Bitcoin energy usage is from renewable sources (many of which would otherwise be curtailed and otherwise unfunded due to flat-to-falling demand for electricity). But PoW really is expensive and hopefully the market will choose less energy-inefficient solutions from the existing and future blockchain solutions while keeping equal or better security assurances.

>> Proof of Work (Bitcoin, ...), Proof of Stake (Ethereum Casper), Proof of Space, Proof of Research (GridCoin, CureCoin,)

The spec should be: DDOS resiliant (without a SPOF), no one entity with control over API and/or database credentials and database backups and the clock, and immutable.

Immutability really cannot be ensured with hashed records that incorporate the previous record's hash as a salt in a blocking centralized database because someone ultimately has root and the clock and all the backups and code vulnerable to e.g. [No]SQL injection; though distributed 'replication' and detection of record modification could be implemented. git push -f may be detected if it's on an already-replicated branch; but git depends upon local timestamps. google/trillian does Merkle trees in a centralized database (for Certificate Transparency).

In quickly reading the git-signatures shell script sources, I wasn't certain whether the git-notes branch with the .gitsigners that are fetched from all n keyservers (with DNS) is also signed?

I also like the "Table 1: Security comparison of Log Based Approaches to Certificate Management" in the CertLedger paper. Others are far more qualified to compare implementations.