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Oak, a Free and Open Certificate Transparency Log (letsencrypt.org)
143 points by dankohn1 8 days ago | hide | past | web | 18 comments | favorite





Interesting model having a firm sponsor a specific part of the infrastructure. Don't think I've seen this before, reminds me of sports style sponsorships.

Great that lets encrypt gets funding, long may it continue!


The existing CT logs are (almost all) each run by individual companies.

https://crt.sh/monitored-logs

But this might be the first time that a company has sponsored a CT log without operating that log itself.


Awesome! I love CT logs and use a service called Cert Spotter [0] to notify me every time a new cert is generated for one of my domains. This knocks out their Q1 goal [1], I'm very excited about their Q2 goal of Multi-Perspective Validation [2]. It will make getting a cert issued to a malicious actor via BGP hijacking much more difficult. I'm also excited about them getting a ECDSA root certificate and was bummed out when it de-prioritized from being a 2018 feature, but Multi-Perspective Validation is certainly a better priority. All this provided for free, lets encrypt is certainly one of my favorite non-profits [3].

[0] https://sslmate.com/certspotter/

[1] https://letsencrypt.org/upcoming-features/

[2] https://letsencrypt.org/2018/12/31/looking-forward-to-2019.h...

[3] https://letsencrypt.org/donate/


Great use case for blockchain technology

I'd say "great replacement for blockchain technology" (in some applications)

CT logs are already chained

> Great use case for blockchain technology

>> CT logs are already chained

Trillian is a centralized Merkle tree: it doesn't support native replication (AFAIU?) and there is a still a password that can delete or recreate the chain (though we can track for any such inappropriate or errant modifications (due to e.g. solar flares) by manually replicating and verifying every entry in the chain, or trusting that everything before whatever we consider to be a known hash (that could be colliding) is unmodified (since the last time we never verified those entries)).

According to the trillian README, trillian depends upon MySQL/MariaDB and thus internal/private replication is as good as the SQL replication model (which doesn't have a distributed consensus algorithm like e.g. paxos).

A Merkle tree alone is not a blockchain; though it provides more assurance of data integrity than a regular tree, verifying that the whole chain of hashes actually is good and distributed replication without configuring e.g. SSL certs are primary features of blockchains.


There are multiple certificate issuers, multiple logs, and multiple log verifiers. With no single point of failure, that doesn't sound centralized to me?

Which components of the system are we discussing?

PKI is necessarily centralized: certs depend upon CA certs which can depend upon CA certs. If any CA is compromised (e.g. by theft or brute force (which is inestimably infeasible given current ASIC resources' preference for legit income)) that CA can sign any CRL. A CT log and a CT log verifier can help us discover that a redundant and so possibly unauthorized cert has been issued for a given domain listed in an x.509 cert CN/SAN.

The CT log itself - trillian, for Google and now LetsEncrypt, too - though, runs on MySQL; which has one root password.

The system of multiple independent, redundant CT logs is built upon databases that depend upon presumably manually configured replication keys.

Does my browser call a remote log verifier API over (hopefully pinned with a better fingerprint than MD5) HTTPS?


There are multiple issuers, so from an availability point of view, if one is down, you could choose another. They submit to at least two logs, so if one log is unavailable you could read the other one. This is a form of decentralization.

Now, from a security point of view, it only takes breaking into one issuer to issue bad certificates. But maybe classifying everything as either centralized or decentralized is too simple?


I'd say it's more of a tree than a chain, but yes. https://www.certificate-transparency.org/log-proofs-work

Blockchain is also a tree, it's just that every branch except one is (usually) abandoned rapidly.

That said, that's just because both use Merkle trees. CT isn't a blockchain.


Its creators also make it very clear that it is not a blockchain. It’s centralized and lacks the consensus mechanism that’s a hallmark of blockchains (PoW or PoS).

Unfortunately people have started taking the pre-existing components of the Blockchain, like Merkle Trees, and calling them "blockchain" too. See "permissioned blockchain".

If I had $1 for every time I’ve heard “did you know git is a blockchain”...



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