Tag Info

Hot answers tagged

187

It is already done: It is the FPKI root CA, under explicit and full control of the US government. Windows already trusts it by default. Before you flip out and begin to delete root CA certificates, burn your computer's motherboard, or drink a gallon of vodka, think about what it means. It means that the US government could technically emit a fake ...


59

In essence, these certificates are necessary and required for backward compatibility with XP and Server 2003. If anything was signed with these certificates, even if they're expired now, your server needs the cert trusted in order to trust the thing that the cert signed. Source: http://support.microsoft.com/kb/293781 Some certificates that are listed in ...


33

The NSA could and probably already has gone -- using a USA PATRIOT Act demand letter, or other similar legislative tool -- to all the major CAs in the United States (e.g. VeriSign, GeoTrust, etc.) and demanded that they remit their private root keys to "No Such Agency", "for purposes of 'national security'". Of course, all such requests must (per PATRIOT ...


28

Mostly yes, any CA in your trusted root, (or subordinates) can issue a cert for any DNS name. Name constraints and Enhanced Key Usage can be used to mitigate this, but they aren't enforced everywhere. DANE, Certificate Pinning, and Certificate transparency are a few projects that help protect from this risk.


22

Certificates are signed and the cryptographic signature is verified; if the signature matches then the certificate contents are exactly as they were when the certificate was signed. This, of course, does not solve the problem, it merely moves it around. The complete structure is called a PKI. The certificates which are preinstalled in your computer (came ...


21

Solved. The problem was indeed triggered by installing Apple Mavericks/ML Security Update 2015-004. As mentioned in this Apple release note, it included updates to the certificate trust policy. There was a duplicate certificate installed (with a wrong serial no.), removing it fixed the problem. The serial number for the cert as published by Apple matched ...


17

Can any CA sign any cert for any domain? In general, yes. Trusted root certs are trusted for anything under the root. If the answer is yes, what prevents having two different CAs creating a valid cert for the same domain? Nothing - it's completely legitimate for you, the owner of example.com, to go get a certificate for www.example.com issued by ...


15

You can add, for example the -sha256 flag to the OpenSSL command line when generating the CSR. I don't believe any CA will change how they sign your CSR based on this, and it certainly won't affect the certificate chain. They're not resigning the cert chain for each key, the only signature operation they do is on your CSR itself. Any intermediate/root CAs ...


15

It's prevented through legal (contractual) and not technical means. What happens if a CA creates an certificate which is not duly authorized by the legitimate domain owner: Time passes, with users unknowingly trusting the fraud. Somebody notices and reports it. Browser vendors remove that CA's root certificate from the next update to the trusted list All ...


15

Google blogged about flagging Certificates using SHA-1 here -> Gradually sunsetting SHA-1 There's no reason to get a new certificate yet as Chrome won't be actually blocking the certificate just treated as “secure, but with minor errors”, I believe that some issuers are offering to reissue certificate but as always, YMMV.


14

There is nothing at all wrong with running your own internal certificate authority; the vast majority of large companies that I have interacted with have their own internal CA. Advantages The nominal cost of a cert becomes nearly zero when amortized over enough systems and users; when you purchase certificates from an external CA, this will never become ...


13

No. In addition to the obvious government Root CAs in your trust stores; the NSA is a spy agency and as such has likely already stolen the private keys of several other CAs. If they are devious, they'd steal the private keys of other government CAs for potential false flag operations. Additionally, unless every operating system and browser explicitly locks ...


10

It's not at all clear to me what you don't understand, so I'll take it very slowly. First some terminology. It's important to get this straight, because otherwise you can't know correctly what you're hearing and saying. Key pair: a private key and a corresponding public key which are mathematically related and used for public-key cryptography (PKC) also ...


10

So we had to install their root certificate "PrivateCompany Root CA" to our web server. Why? Globally trusted CAs are useful in general purpose clients like browsers. But if you consume specific web services from a custom client you can add that CA locally. Every decent SSL client allows you to influence certificate validation. For example by ...


10

There are multiple ways to exploit a compromised certificate. If you have a compromised website certificate, you need to get people onto your server when they type the address of the compromised one. This can be done: By getting control of a DNS server, there you can basically change the association of a website URL to your server IP address. By ...


10

First of, CRL do not cover root CA. By definition, a root CA is a root: it has no issuer except itself. A CRL conveys revocation information, which is a way for a certificate issuer to announce that a previously issued certificate should be considered as invalid even though it looks fine and its signature is correct and everything. Thus, a CRL that talks ...


8

... But in reality, a self-signed cert is not significantly less secure than a cert signed by a CA - in the sense that your traffic is encrypted and sent to the web server and decrypted there. It just means that no one "trusted" checked the identity of the webserver in question. This just is a very important part. If you don't verify, that the peer you ...


8

Public Key Cryptography designates the class of cryptographic algorithms that includes asymmetric encryption (and its cousin key exchange) and digital signatures. In these algorithms, there are two operations that correspond to each other (encrypt -> decrypt, or sign -> verify) with the characteristic that one of the operations can be done by everybody while ...


7

It's a rather short list: ‘admin’, ‘administrator’, ‘webmaster’, ‘hostmaster’, or ‘postmaster’ Now that's the fixed and static list. But: contact info from WHOIS is also legal. From the CAB-Forums' Baseline requirements, page 17: 11.1.1 Authorization by Domain Name Registrant For each Fully-Qualified Domain Name listed in a Certificate, the CA SHALL ...


7

You don't need to get another new certificate. In order to resolve this issue, you need to just reissue your certificate with SHA-2 signature. That's it.


6

The question is... a bit complex. The critical issues are existence and availability of intermediate CA certificates. Consider the following points: Root CA are not "revoked". Revocation is a mechanism by which the issuer for a given certificate specifies, directly or indirectly, that one of its issued certificates is not to be trusted and must not be used ...


6

From RFC 5280 3.3 Revocation An entry MUST NOT be removed from the CRL until it appears on one regularly scheduled CRL issued beyond the revoked certificate's validity period. If you have a lot of changes (people leaving etc.) it's best to not make the certificate validity too long otherwise the CRL can grow large (some CRLs are > 30MB which ...


6

There is only full trust with the CAs you've installed. This means, that there is no restriction which certificates a trusted CA can sign. So it can also sign fake certificates for sites they don't own (e.g. banking.com) and you will accept them. I don't know how you communicate with the partner, but with languages like Perl, Python etc you can specify a CA ...


6

If a virus installs a new root certificate on your computer, and a spoofed website presents you with a certificate with a valid signature chain from that root certificate, then your computer will accept it as a valid certificate. But this shouldn't be seen as a problem with SSL/TLS -- if you have a virus with that level of access, then there are lots of ways ...


5

To answer your first question: As far as I know, there is no way to circumvent this. It's a security feature. To answer your second question: Yes, non-default trusted root certs are definitely potentially problematic. They are often abused. They are sometimes used for workplace or traffic monitoring (which is potentially OK if adequately disclosed, ...


5

There is no global directory of all issued certificates (X.509 was designed to support the Directory, but it never existed in practice). You will have to contact "all CA" and ask them nicely. Basically, this would mean going to their site, and using the "I lost my password" feature so as to regain control of your account, if it exists. Details vary depending ...


5

It's safe as long as you understand the implications. Fiddler acts as a proxy / man in the middle to intercept and decrypt traffic between you and the target. For SSL sites, it does this by dynamically generating an SSL certificate with the name of the target. The problem is that your browser will not trust certificates issued by Fiddler, hence the ...


5

Others have mentioned mitigation techniques, here are some examples: Questionable Compromises Antivirus manufacturers like Kaspersky frequently install a CA in order to "protect" you by eavesdropping on all your connections, including SSL links. In February 2015, media covered the SuperFish adware / malware deliberately installed by Lenovo on its ...


5

Certificate Authorities cross-sign each other when they get married together. When CA Y issues a certificate for CA Z, then any system who trusts Y will indirectly gain confidence in everything that Z issues, since, for any certificate X issued (signed) by Z, a system that trusts Y will build the chain Y→Z→X. Thus, this cross-certification represents an ...


5

Within SSL/TLS, the server sends its certificate chain systematically to the client (well, unless the client wants to negotiate a cipher suite that uses no certificate at all, but that's pretty rare in practice). See the TLS standard, in particular this diagram, which says it all: Client Server ClientHello ...



Only top voted, non community-wiki answers of a minimum length are eligible