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Transparent Logs for Skeptical Clients

research.swtch.com

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Re: Transparent Logs for Skeptical Clients

#2

Post by lachenmayer »

The hypercore[1] signed append-only log which is the heart of the Dat protocol[2] is an implementation of very similar ideas. The data structure consists of an append-only log, a Merkle tree (stored in the "inorder storage layout" described in Appendix B), and signatures for each of the root hashes of the Merkle tree. The public key ("read key") of the key pair which is used to sign the tree roots can be used as a unique identifier of the contents of the log, eg. for looking up peers in a DHT which can serve the contents. It features a replication protocol which is similar to the one described in the article (if you squint hard enough). A fantastic in-depth explainer of the data structure and the protocol is available at [3].

The current implementation is in Node.js, but a Rust port is under way. [4]

[1]: https://github.com/mafintosh/hypercore [2]: https://www.datprotocol.com/ [3]: https://datprotocol.github.io/how-dat-works/ [4]: https://github.com/datrs/hypercore

Re: Transparent Logs for Skeptical Clients

#4

Post by nickpsecurity »

flipp3r wrote: post #3

Literally just a usecase for a blockchain, reinvented..

It's a hashchain. They predate blockchains. I used them a long time as just signed, text files full of hashes. Trusted Timestamping used them. Blockchains were a highly-wasteful modification of hashchains for a different purpose. Databases, logs, and hashchains are still better for most things. Centralized services with decentralized checking of a signed log is still more efficient since centralized tech is itself more efficient.

Re: Transparent Logs for Skeptical Clients

#7

Post by rzzzt »

lachenmayer wrote: post #2

The hypercore[1] signed append-only log which is the heart of the Dat protocol[2] is an implementation of very similar ideas. The data structure consists of an append-only log, a Merkle tree (stored in the "inorder storage layout" described in Appendix B), and signatures for each of the root hashes of the Merkle tree. The public key ("read key") of the key pair which is used to sign the tree roots can be used as a un…

I wish other protocols were described in "How Dat Works"-style. Very nicely done.

Re: Transparent Logs for Skeptical Clients

#9

Post by geofft »

flipp3r wrote: post #3

Literally just a usecase for a blockchain, reinvented..

This is different from a blockchain because it's more efficient - the length of a log proof is O(log(N)) instead O(N). A blockchain in the Bitcoin sense does not satisfy properties 1, 2, and 3 in this article.

Re: Transparent Logs for Skeptical Clients

#10

Post by darkerside »

nickpsecurity wrote: post #4
flipp3r wrote: post #3

Literally just a usecase for a blockchain, reinvented..

It's a hashchain. They predate blockchains. I used them a long time as just signed, text files full of hashes. Trusted Timestamping used them. Blockchains were a highly-wasteful modification of hashchains for a different purpose. Databases, logs, and hashchains are still better for most things. Centralized services with decentralized checking of a signed log is still more efficient since centralized tech is itself mo…

I was hoping this would be more informative...

https://en.wikipedia.org/wiki/Hash_chain#Hash_chain_vs._bloc...

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