There is a massive security incident this week where an Indian certificate authority used 4 as the private key they used to sign encrypted internet traffic with.
Knowing their secret key lets anyone forge certificates that they can use to snoop on or modify internet traffic.
All 8 of their private keys were under 255, so could be trivially guessed. These certificates were accepted by all major browsers and operating systems, as well as many programming languages and tools.
I think it technically was not “brute forcing” (since it wasn’t found by searching the entire key space), but specifically someone tried generating CA cert private keys from numbers 0-255, and surprisingly found a few.
It’s just as arbitrary as any other number. You can pick at random, but starting with a dictionary attack of easy, non-random keys would probably be a better start.
I remember playing a game of dvd-deal or no deal, where you would pick random number from one to twenty and see if you won money. The people I was playing with were mad because I just started guessing 1, 2, 3, 4…
I told them statistically it was just as likely to be those numbers as anything else.
No it absolutely does, the method they used to generate private keys ended up having just 8 shannons of entropy which led to the discovery we are discussing
Nit: That that key doesn’t technically encrypt traffic, if I understand correctly. It’s used to verify the identify of a website. So someone with this private key can’t directly read internet traffic. They can set up a man-in-the-middle attack, but they’d also have to compromise DNS to pull it off.
It’s a little more complex than that. But if you want to encrypt, and you do want your site traffic encrypted, you use site certificate to give the client browser proof that you are who you say you are. You do this by establishing a chain of trust: “I got this proof that I am who I say I am from this major trusted certificate authority” you trust them and they trust me, so we’re all good. You’ve probably seen the warning that a site isn’t secure, and that’s because they let their certificate of trust expire.
This low entropy key means it’s trivial for me to fake that I have that major authority’s trust. The browser needs to be updated to no longer trust that authority. Until it does I can easily fake being anyone and say that compromised site vouches for me. I don’t even need to be a man in the middle, I just need to set up a way that your browser sends you to my fake server instead of the real one. Lots of ways to do that.
I just dont understand why they would do this? Putting so shitty key is like they wanted to make it as insecure as possible. Even if the ones responsible were criminally stupid, they still should have understood that this is like leaving the whole thing unlocked.
And for such critical thing. Imagine if this wasnt discovered like this but instead by some competent malicious actor that had resources to coordinate some large scale attack and kept it hidden until just the right moment when they can strike at everything.
I also dont understand how little outrage there even is about this, we were really close to huge catastrophe. Or maybe i have misunderstood the severity of what happened.
They are saying there were mistakes made with their key generation scripts:
We have done some preliminary assessment, there appears to be a flaw in the KGC script that was used on that specific day to create these ECC issuers. As for these ECC keys, our review of the KGC, assessment of the code and view of HSM keys so far indicate that a) a set of original ECC keys were created onboard as expected b) an approved deviation to our usual KGC to test a wrap/unwrap was introduced as these keys were meant for export for this instance c) a flaw in the code resulted in the second pair of keys being created onboard which were weaker d) these second pair of weaker keys were used by mistake to create the csr (because the key labels were similar) and signed by our root e) the CSR from these weaker keys were also sent over to Sectigo for cross signing (we verified the files sent over to Sectigo)
I’m not so sure. Because shortly after the above quote they answered this to the next question:
Is there any reason which may explain why the A and A-1 ECDSA keys appear to be unaffected by similar issues?
The A and A-1 series were created in Entrust HSMs and were meant for deployment only in India.
And previously in Comment 10 they said about the bad keys
These ICAs were generated from the same key ceremony on Apr 30, 2025. The G3B and G3C ICAs were created for European and US operations respectively but they were not put into production except #2 in the list below but no end entity certificates were issued from these. The Code Signing issuers were not put into production also did not issue any certificates.
That’s why I think somehow the intended place of use made a difference in their process. But it could be you’re right and they still mean HSM export, because the keys need to go to the region of use, and aren’t transported physically in the HSM.
Interesting question! Google spit this out and it makes sense:
The primary reason these specific keys/issuers were created was to solve data sovereignty and data residency requirements for customers in those regions.
Many European and US corporate clients operate under strict legal frameworks (like GDPR in Europe or various federal compliance standards in the US) that legally dictate where cryptographic infrastructure can live, where data can be decrypted, and who can possess the root or intermediate private keys.
Generating separate regional keys is a compliance mechanism to guarantee that a customer’s data or handshake traffic stays within their jurisdiction.
Google is wrong. There is no security benefit to using an SSL certificate signer in your jurisdiction because a hacked or malicious certificate authority in another jurisdiction can man-in-the-middle you or your customers just as effectively.
Certificate authorities do not decrypt data or even transfer it on behalf of customers.
There is a massive security incident this week where an Indian certificate authority used 4 as the private key they used to sign encrypted internet traffic with.
Knowing their secret key lets anyone forge certificates that they can use to snoop on or modify internet traffic.
All 8 of their private keys were under 255, so could be trivially guessed. These certificates were accepted by all major browsers and operating systems, as well as many programming languages and tools.
But, since nobody would expect an organization like that to have a one digit key, wouldn’t that make it extremely hard to guess?
Half kidding here.
Not if you’re brute forcing it.
I think it technically was not “brute forcing” (since it wasn’t found by searching the entire key space), but specifically someone tried generating CA cert private keys from numbers 0-255, and surprisingly found a few.
Ain’t no way I’m starting from 0 if the standard key is 256-bit
It’s just as arbitrary as any other number. You can pick at random, but starting with a dictionary attack of easy, non-random keys would probably be a better start.
I remember playing a game of dvd-deal or no deal, where you would pick random number from one to twenty and see if you won money. The people I was playing with were mad because I just started guessing 1, 2, 3, 4…
I told them statistically it was just as likely to be those numbers as anything else.
Well, someone did guess it so it’s not that hard. The entropy was really low.
‘Entropy’ doesnt apply here
No it absolutely does, the method they used to generate private keys ended up having just 8 shannons of entropy which led to the discovery we are discussing
Nit: That that key doesn’t technically encrypt traffic, if I understand correctly. It’s used to verify the identify of a website. So someone with this private key can’t directly read internet traffic. They can set up a man-in-the-middle attack, but they’d also have to compromise DNS to pull it off.
Yes, I think you’re correct
It’s a little more complex than that. But if you want to encrypt, and you do want your site traffic encrypted, you use site certificate to give the client browser proof that you are who you say you are. You do this by establishing a chain of trust: “I got this proof that I am who I say I am from this major trusted certificate authority” you trust them and they trust me, so we’re all good. You’ve probably seen the warning that a site isn’t secure, and that’s because they let their certificate of trust expire.
This low entropy key means it’s trivial for me to fake that I have that major authority’s trust. The browser needs to be updated to no longer trust that authority. Until it does I can easily fake being anyone and say that compromised site vouches for me. I don’t even need to be a man in the middle, I just need to set up a way that your browser sends you to my fake server instead of the real one. Lots of ways to do that.
I just dont understand why they would do this? Putting so shitty key is like they wanted to make it as insecure as possible. Even if the ones responsible were criminally stupid, they still should have understood that this is like leaving the whole thing unlocked.
And for such critical thing. Imagine if this wasnt discovered like this but instead by some competent malicious actor that had resources to coordinate some large scale attack and kept it hidden until just the right moment when they can strike at everything.
I also dont understand how little outrage there even is about this, we were really close to huge catastrophe. Or maybe i have misunderstood the severity of what happened.
They are saying there were mistakes made with their key generation scripts:
Source: https://bugzilla.mozilla.org/show_bug.cgi?id=2083449#c11
Personally I’m still a little confused why it makes any difference that the keys were intended for export to their European and US operations
By “export” I think they mean export off of the hardware security module (HSM). Not export geographically.
I’m not so sure. Because shortly after the above quote they answered this to the next question:
And previously in Comment 10 they said about the bad keys
That’s why I think somehow the intended place of use made a difference in their process. But it could be you’re right and they still mean HSM export, because the keys need to go to the region of use, and aren’t transported physically in the HSM.
Interesting question! Google spit this out and it makes sense:
The primary reason these specific keys/issuers were created was to solve data sovereignty and data residency requirements for customers in those regions.
Many European and US corporate clients operate under strict legal frameworks (like GDPR in Europe or various federal compliance standards in the US) that legally dictate where cryptographic infrastructure can live, where data can be decrypted, and who can possess the root or intermediate private keys.
Generating separate regional keys is a compliance mechanism to guarantee that a customer’s data or handshake traffic stays within their jurisdiction.
Google is wrong. There is no security benefit to using an SSL certificate signer in your jurisdiction because a hacked or malicious certificate authority in another jurisdiction can man-in-the-middle you or your customers just as effectively.
Certificate authorities do not decrypt data or even transfer it on behalf of customers.
It’s about compliance, not security.