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12

In SSL/TLS the server is supposed to show its certificate as part of a chain. Theoretically, the server should make sure that the sent chain is correct, and the client is "morally entitled" to reject the connection if the exact chain sent by the server fails to validate. However, clients are allowed to make extra efforts; if they can validate the certificate ...


8

The first example is a normal SSL certificate meaning that it's a valid certificate issued by a trusted Certificate Authority, but there was no extended validation of the owner of the domain/site. This could mean that the certificate claims to be from Foo Inc. but the CA did not check that the person/entity applying for the certificate was indeed Foo Inc. ...


6

Once a computer boots, the operating system is given near exclusive control over the system resources (kernel access). After this occurs, if a program wants to run, it must ask the OS to let it run. Before iOS allows an application to run, it examines the code that is going to be loaded in to memory from the binary and checks it against a signed value that ...


6

This answer applies to SSL or PGP type digital certificates, which bind an identity to a public key. It has been pointed out to me that the question as originally asked did not specify what kind of certificate, so my answer may not fit the question. Digital certificates which bind an identity to a public key do not need special security because they ...


5

An app must be code signed with a certificate issued by Apple. Whenever an app is run this signature is checked using its public key. As long as the certificate chain is traced back to Apple as the Certificate Authority, then the app is authenticated. More info on Code Signing. This is a bit of a generalization. Detailed guide from Mac Developer Library ...


5

It's actually not a SHA1 hash in the CSR. It's a signature of the message. For simplicity, I'll assume we are talking about RSA certificates, where the public key is (N, e) (the modulus and public exponent which is typically 65537) and the private key is (N, d) (the modulus and the private exponent which can be easily calculated via Euclid's extended ...


5

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 ...


3

Advisories recommend 2048 for now. Security experts are projecting that 2048 bits will be sufficient for commercial use until around the year 2030. The main downside to using a large cert, such as 3072 or 4096, is that the algorithm is slightly slower (still fractions of a second, though). Current browsers should all support certs upto 4096. Some CAs ...


3

The server always sends a chain. As per the TLS standard, the chain may or may not include the root certificate itself; the client does not need that root since it already has it. And, indeed, if the client does not already have the root, then receiving it from the server would not help since a root can be trusted only by virtue of being already there. What ...


3

You can only use the ECDHE-RSA ciphers from that list if all you have is an RSA certificate. Same thing for ECDSA certificates, which only can be used with the ECHDE-ECDSA ciphers on that list. ECDH-* is fixed in the sense that your certificate contains the fixed public parameters for and key, which can be used for the key exchange. This certificate is then ...


3

According to Section 7.1 of the Extended Verification Guidelines a certificate verifies the following: (A) Legal Existence: The CA has confirmed with the Incorporating or Registration Agency in the Subject’s Jurisdiction of Incorporation or Registration that, as of the date the EV Certificate was issued, the Subject named in the EV Certificate ...


3

Browser usually cache intermediate certificates which they've seen once. This can be tested if you use firefox against a server which missing a common intermediate certificate. If the browser has seen this missing certificate already it will allow the connection. But, if you use a fresh firefox profile and retry it will complain, because the certificate ...


3

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 ...


2

When you access http://www.amazon.com and click Login, it redirects you to https://www.amazon.com which is secure. Note: This is susceptible to sslstrip and they should be forcing SSL/TLS using HSTS.


2

In such a case when multiple websites are served from the same server on the same port, that server differentiates between them by comparing the Host: header in the HTTP request. Once TLS negotiation has occurred, it is not possible to read anything inside that request. You further cannot swap between two simultaneous SSL connections because a simple ...


2

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 ...


2

A cookie has only one function: to be sent back to the server. It is stored on the client, but the client does not understand its contents; and the client does not use it except by sending it back. Which basically explains that the "answer" you quote is not a real answer: it tries to side-step the problem by stating that side-stepping the problem would be ...


2

You don't issue certificates with an SSL certificate -- you issue certificates with an intermediate CA certificate. That's a different beast; namely, contrary to what is colloquially known as "an SSL certificate", an intermediate CA certificate is granted CA power by virtue of including a Basic Constraints extension with the cA flag set to TRUE. Presence of ...


2

This could be due to the length restrictions on certificate keys. Microsoft enforced a minimum key length limit of 1024 bits in August 2012. Check that your self signed cert is created with a key length of at least 1024 bits. For more info you can check out this blog post What does the “This certificate has an invalid digital signature.” message actually ...


2

The "ValiCert Class 2 Policy Validation Authority" root from 1999, along with about a dozen other roots from ValiCert and other CAs, are being phased out because they're only 1024 bits. 1024-bit RSA is increasingly close to being breakable1, so the community has decided to get rid of them in an orderly manner by 20112 to prevent a major security incident and ...


2

The difference is that the lower bar indicates an Extended Validation certificate, and the upper bar doesn't. See the support page.


2

As far as I am aware there is not. I don't believe that CAcert.org was really ever accepted widely by browsers if I remember right. You can get second-level domain certificates for fairly cheap though through GlobeSSL or SSLs.com and by fairly cheap I mean for about $10.00/year. I personally find SSLS.com easier to use than Globe but both are good.


2

Pre-Snowden, I would have dismissed this question as being in the "tinfoil hat" category. Unfortunately, the NSA's pervasive misconduct (not to mention that of its "Five Eyes" junior partners, e.g. GCHQ, CSIS, and whatever the Australian and N.Z spook agencies are calling themselves these days), does indeed raise a troubling question. The specific ...


2

Key pairs are used for two things: Encrypting a secret value for symmetric encryption Signing data for validation Both RSA and DH are based in asymmetric algorithms. So we have two cases for a secure exchange to occur. RSA Alice signs a message to Bob, and encrypts the message with Bob's public key. Sends message to Bob. Bob decrypts with his ...


2

Expiration date is "baked" into certificate itself, so even if time on client is incorrect this wouldn't cause server to mistakenly accept the certificate. Server clock, on the contrary, have to be correct. Now, whether or not it is safe to remove expired certificates from the CRL depends on how server verifies certificates and, in particular, whether it ...


1

Your point 4 is a bit unclear: is it a problem if clients start to claim that they did not receive the "material", while in fact they did ? If it is not a problem, then what you basically need is: A SSL connection to your server. The server's certificate must be recognizable as valid by the clients. Since the client software is under your control, you ...


1

Authentication is about reliably recognizing who is at the other end. Since, from the server, you "see" the client only through network packets, and since everybody can buy the same kind of hardware, you may hope to properly authenticate a specific client only if that client is able to compute things that other systems would not. This implies that the client ...


1

Take into account that there are server software (like IBM HTTP Server) that will not start at all if the root CA is not included in the keystore.


1

I send the root when it is convenient to do so. If the client trusts the root, then it makes no difference whether you send it or not. When the client does not recognize the root, in my experience the MS Windows client produces much less confusing diagnostic messages if the untrusted root was provided in the chain. As for how it knows what root to use if ...


1

what does a browser use to compare against for validation since the server won't be supplying its root cert during the handshake The whole idea of certificate checking is that the clients has some root certificates it trusts (shipped with the browser or OS) and that it validates the certificate the browser sends against this local trust anchor. This ...



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