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Trusted certificate authority Certigna leaks its private key

thinq.co.uk

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Re: Trusted certificate authority Certigna leaks its private key

#11

Post by EwanToo »

yuhong wrote: post #10
EwanToo wrote: post #8

I don't think this leak has included their own certificate authority key to allow you to generate your own key signed by the CA (which thinq claims), just the private key for the website, but it's certainly embarrassing for them. They seem to have modified all the files in the directory overnight, and removed the offending www.certigna.fr files from http://www.certigna.fr/crl/ (unless the website has an archived dire…

Well, unfortunately there are also other .pem files in the list.

But that doesn't mean their CA trusted root key has been disclosed - sure, the pem files could contain their trusted root key, but they normally wouldn't.

For example, the file named certigna.pem exists on most Linux machines, it's the public key not the private one, look at the ca-certificates package on debian.

Re: Trusted certificate authority Certigna leaks its private key

#12

Post by wladimir »

pagekalisedown wrote: post #9
wladimir wrote: post #3

Earlier quoted context omitted.

I'm not sure either. If it is encrypted, it would at least buy some time to replace all the certificates signed by this private key. Depending on the strength of the encryption key, obviously.

Just by looking at the PEM's number of lines you can tell it's a 1024 bit key.

That's the private key itself. I was somewhat unclear in my wording. We (I and the grandparent poster) were wondering if the private key was encrypted with a passphrase.

Re: Trusted certificate authority Certigna leaks its private key

#13

Post by zwp »

JoachimSchipper wrote: post #4

Of course, "just revoke" doesn't actually work: serving a outdated certificate revocation list, or preventing a connection to the OCSP ("is this cert revoked?") server causes browsers to trust "revoked" certificates. Worse, lots of software doesn't even bother to do this check. This is why the browsers hardcoded a list of compromised certificates last time. This is even worse, though, because a lot of "real" certific…

"a lot of "real" certificates depend on this CA"

How many? did you estimate from sequential serial number allocation?

I am surprised (even if it turns out this is "just" an encrypted webserver key) that they aren't using hardware keys: (a) it's their core business (b) they appear competent (CTO posts to technical mailing lists) (c) they have a /29 so aren't just a single IP on an inaccessible low-end VPS.

ssllabs.com gives them a C rating.

Re: Trusted certificate authority Certigna leaks its private key

#15

Post by jvehent »

This would actually be a problem.... if the private key was good for anything. Certigna's response says it is not:

"Certigna has issued a response claiming that the file represented a 'test' certificate that had long since expired. "The private key available on the server corresponds to a test certificate used on our website certigna.fr," the company claimed. "It is impossible to generate new valid user certificates from this key. Moreover, it is encrypted and is an SSL certificate expired since July 2010. This key does not affect our infrastructure security. The Certigna SSL authority’s private key is stored in HSM (Hardware Security Module) and hence can never be recovered. This useless file has been removed."

Re: Trusted certificate authority Certigna leaks its private key

#17

Post by verroq »

Robin_Message wrote: post #14

That level of blurring is almost certainly insufficient to actually redact the information, as discussed in http://dheera.net/projects/blur.php (discussed here http://news.ycombinator.com/item?id=1939607 )

I don't think so, it'd take way too long to dictionary attack/bruteforce the missing 64 x 9 characters of the blurred image. Which gives 64 ^ (64 x 9) combinations judging from the base64 encoding.

That is assuming you have the blurring algorithm and font perfect.

Re: Trusted certificate authority Certigna leaks its private key

#18

Post by ordinary »

jvehent wrote: post #15

This would actually be a problem.... if the private key was good for anything. Certigna's response says it is not: "Certigna has issued a response claiming that the file represented a 'test' certificate that had long since expired. "The private key available on the server corresponds to a test certificate used on our website certigna.fr," the company claimed. "It is impossible to generate new valid user certificates…

Just some sensationalist reporting without proper fact-checking, then. Again.

Re: Trusted certificate authority Certigna leaks its private key

#19

Post by pagekalisedown »

wladimir wrote: post #12
pagekalisedown wrote: post #9

Earlier quoted context omitted.

Just by looking at the PEM's number of lines you can tell it's a 1024 bit key.

That's the private key itself. I was somewhat unclear in my wording. We (I and the grandparent poster) were wondering if the private key was encrypted with a passphrase.

Good point. The strength of the private key isn't relevant. Only the encryption used to protect the key.

Re: Trusted certificate authority Certigna leaks its private key

#20

Post by meric »

verroq wrote: post #17
Robin_Message wrote: post #14

That level of blurring is almost certainly insufficient to actually redact the information, as discussed in http://dheera.net/projects/blur.php (discussed here http://news.ycombinator.com/item?id=1939607 )

I don't think so, it'd take way too long to dictionary attack/bruteforce the missing 64 x 9 characters of the blurred image. Which gives 64 ^ (64 x 9) combinations judging from the base64 encoding. That is assuming you have the blurring algorithm and font perfect.

What prevents you from doing it with only 5 letters at a time?
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