469 reputation
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bio website chiark.greenend.org.uk/~armb
location Cambridge, UK
age 50
visits member for 1 year, 8 months
seen 14 hours ago

1d
comment How can I know that the CA certificates in my computer have not been spoofed?
Thanks - link fixed
1d
revised How can I know that the CA certificates in my computer have not been spoofed?
Updated dead link
Oct
15
comment SSL3 “POODLE” Vulnerability
The SSL 3.0 symmetric cipher that doesn't use CBC mode is RC4, which may well be disabled for reasons also well explained by Thomas (and the NULL "cipher") - security.stackexchange.com/questions/32497/tls-rc4-or-not-rc4/…
Sep
17
comment Trying to understand why signatures in root certs “are not used”?
Or, from the other direction, if you can alter the root certificate store (for example by saying "employee, install this corporate root certificate if you want to keep your job", or by patching the browser), you can insert your own certificate regardless of which signature algorithm you use, and regardless of which algorithms legitimate CA certificates used.
Jul
10
comment Generic error message for wrong password or username - is this really helpful?
You could do it this way if your per-row salt was generated from the user name, say by feeding it into HMAC with a secret key. Obviously to avoid timing attacks you need to make sure the password hashing is done whether the username exists or not, but that's trivial.
May
22
comment What's to stop someone from 3D print cloning a key?
I know someone who works in a prison, and he once said he knew several prisoners capable of making a working copy of a key from having seen it across a room.
May
12
comment Key management in cloud datacenters
If the keys are kept on an HSM, VMs snooping on each other won't see the actual key operations. However technet.microsoft.com/en-us/library/dn440580.aspx suggests that all the HSM protected keys in a datacenter are in the same Security World, and that the "Bring Your Own Key" management still needs the key to be exported from your own world into Microsoft's. Security Worlds do allow separation of key protection within the world though, so other users shouldn't be able to use your keys.
May
2
comment Key management in cloud datacenters
Apparently the Microsoft Azure key import used to require you to fly to Redmond yourself, but that's no longer the case: blogs.technet.com/b/rms/archive/2014/03/05/…
May
2
answered Key management in cloud datacenters
Mar
26
comment How to securely share key between two remote devices?
For using standard per user CA signed client certificates, see developer.android.com/training/articles/… nelenkov.blogspot.co.uk/2011/11/using-ics-keychain-api.html
Mar
26
comment How to securely share key between two remote devices?
Actually it might not be necessary that each client have its own certificate. You can build a fixed private key and its associated certificate into the application, and that's sufficient for the server to be able to authenticate that a registration request is coming from a copy of the client (or that someone has reverse engineered the client). Depending on your registration scheme, you may be able to use that to bootstrap per-client certificates.
Mar
21
comment How can you prevent employees of your company from creating valid ssl certs?
As an aside, just an email address is enough to get a client SSL certificate, but it will be for that specific address, not the domain.
Jan
31
awarded  Yearling
Jan
14
comment Relative merits of Heimdal and MIT Kerberos?
True, it's not completely freely exportable, just much much more so than in the 1990s. en.wikipedia.org/wiki/… en.wikipedia.org/wiki/… The still embargoed countries are (I think) Cuba, Iran, Iraq, Libya, North Korea, Sudan, and Syria (though also I've seen lists which omit Iraq ans Libya - the US government page cited is 404 and I haven't bothered to track down where it moved to) cryptolaw.org/cls2.htm#us_terror
Sep
16
comment How can I know that the CA certificates in my computer have not been spoofed?
Something I didn't mention and should have - if your browser has been replaced by a patched copy, the list of root certificates it displays might not be the real list it effectively uses internally. And the certificate it displays when you say "show me details of the current connection" might not be the real one. If you aren't allowed to install new software, even inside a VM, nor run portable software from e.g. a USB memory stick, there's not much you can do about that. That's going further than the scenario in your original question though.
Sep
12
comment How can I know that the CA certificates in my computer have not been spoofed?
(Also, to a first approximation, OCSP doesn't work: imperialviolet.org/2011/03/18/revocation.html)
Sep
10
answered Relative merits of Heimdal and MIT Kerberos?
Sep
4
comment What is certificate pinning?
Fuller details of how it's done (or how it might be done when draft proposals are standardised): owasp.org/index.php/Certificate_and_Public_Key_Pinning tools.ietf.org/html/draft-ietf-websec-key-pinning tack.io/index.html imperialviolet.org/2011/05/04/pinning.html
Aug
22
revised How can I know that the CA certificates in my computer have not been spoofed?
Add certificate pinning/DANE
Aug
22
comment How can I know that the CA certificates in my computer have not been spoofed?
If someone has inserted a root CA, then it will point at an OCSP server they control.