Comment by justin_ | Hacker News Reader

Comment by justin_ | Hacker News Reader

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Linus himself has credited Monotone with the content-addressing by SHA1: https://marc.info/?l=git&m=114685143200012

I think the main issue with Monotone was the performance. Linus also hates databases and C++.

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Hoare didn't come up with this idea either, but he did apply it to version control. He had potentially been influenced by his earlier work on distributed file systems and object systems. Here's his 1999 project making use of hashes: https://web.archive.org/web/20010420023937/venge.net/graydon...

He was in contact with Ian Clarke of Freenet fame (also 1999). There seems to have been a rise in distributed and encrypted communications around the time, as kragen mentions in his other post.

BitTorrent would also come to use hashes for identifying torrents in a tracker, and would come out in 2001, created by Bram Cohen, the author of the post here :)

thanks for digging up these links

interestingly it does say bk used md5 in some way; i'm not sure how i overlooked that when i was looking at the code earlier, but indeed md5 is used in lots of places (though apparently not for naming objects the way git and monotone do)

the crucial way bittorrent uses hashes actually is for identifying chunks of files (a .torrent file is mostly chunk hashes by volume); that's why it was immune to the poisoning attacks used against other p2p systems in the early 02000s where malicious entities would send you bogus data. once you had the correct .torrent file, you could tell good data from bad data. using the infohash talking to the tracker is convenient but, as i understand it, there isn't really a security reason for it; the tracker doesn't verify you're really participating productively in the swarm, it just sends your IP to other peers in case you might. so there isn't a strong reason to keep torrent infohashes from colliding

Right, bitkeeper doesn't name files with hashes like git does. But it uses sha1 (or similar) for decentralization: to tell if two remote files are the same.

Another player is tridge's rsync, which also uses hashes like that.

aha, thanks

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