A piece of data used in public key cryptography that contains identifying information (i.e. email address or web address), a hash of a public key, and a digital signature that authenticates the data in the certificate.

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Can an intermediate CA be trusted like a self-signed root CA?

Is it possible within the limits of the X.509 specification to mark an intermediate CA as trusted for a specific purpose, e.g. to verify a VPN, HTTPS etc. server key, just like it would work with a ...
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What fields in a suspicious certificate should I look at?

Looking at a certificate for a web-site (in Windows/Google Chrome) I see it lists the following fields Version Serial number Signature algorithm Issuer Valid from Valid to Subject Public Key Basic ...
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Does checking the fingerprint of a self signed certificate improve security?

I am currently developing a component for an application that does TCP communication with a device inside a local area network. I use TLS to provide data encryption, integration and authorisation. ...
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243 views

SSL CipherSuite Choices

In SSL/TLS, is the CipherSuite chosen by the server or the client? Also, can the certificate in any way dictate or modify the CipherSuite?
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What are the benefits and drawbacks of the HTML5 Keygen element?

As of January 2013, what are the potential benefits and drawbacks of the HTML5 Keygen element?
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668 views

Digital Signature and Verification?

AFAIK , When Alice wants to write a message to Bob -- she uses Bob's public key and encrypt the message - and then Bob - using his private key - use to decrypt it. So public key is used to decrypt ...
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99 views

Is it possible to have multiple key lengths in PKI?

Is it possible to have multiple key lengths in a PKI? For example, use a 1024-bit key for the issued certificate, a 2048-bit key for the intermediate certificate, and 4096-bit key for the root ...
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Does a CA need to have the same type of key as the certificates it is signing? RSA / Elliptic Curve (EC/ECDH/ECDSA)

I am making a CA that I hope to be able to sign RSA and Elliptic Curve-capable (EC) keys with. I was wondering if the best approach was: CA with RSA keys capable of signing RSA and EC CSRs CA with ...
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960 views

Why are Certificate Revocation List periodically renewed?

While studying a security course I have been asked this very question: Why are CRL periodically renewed, even if there are no new revoked certificates to add to the list? Honestly I can't find the ...
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380 views

Which attributes of a X509v3 certificate are never really used?

Are there any extensions/extended key usage attributes of a X.509Certificate that are rarely or never used in practice? Either due to never being part of an issued certificate or because they are ...
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782 views

Thunderbird - what happens if Gmail SSL cert gets spoofed?

I use a good MUA: Thunderbird [to read/reply to my emails on Gmail]. So: what happens, if i go to a place, where is public wifi, and someone tryes to sniff my password/username/emails? Questions: ...
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Issuing SSL certificates for device automation software package without domain names

We are developing the automation software for Windows which communicates with the certain devices via our own private connection protocol. That software package consists of several server (including ...
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How is an X509 certificate signer verified?

Lets say I create a self-signed certificate A and use it to issue certificate B. I put certificate A in my trusted root authorities so that all certificates signed by it are accepted. My question is, ...
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Is there an SSL Certificate state-cache on Windows, IE, and Outlook and how it it managed?

Today I changed the SSL certificate that 3,000+ Outlook clients are using. In doing this I changed the certificate to an "older" one that had the same subject name, expiration and everything else. ...
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673 views

Root SSL certificates and browser support

I have given three certs to be install on nginx AddTrustExternalCARoot.crt PositiveSSLCA2.crt www_example_com.crt So I concat them into a chained cert cat www_example_com.crt PositiveSSLCA2.crt ...
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Avoiding MITM attacks when using HTTPS over mobile

There are a variety of other questions that address elements of this security issue, but none that seem (to a non-expert) to address the substantial core of the issues raised in this article: ...
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514 views

Why do we allow SSL certificates to be replaced before their expiry date, without revokation of others?

Imagine a situation where a rogue CA creates a certificate for your site. Since the user's browser trusts the CA, it will accept the certificate without any fuss. However, the site's real certificate ...
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251 views

'Trusted CA Certificates' and 'Trusted remote Certificates'

What is the difference between Trusted CA Certificates and Trusted remote Certificates?
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387 views

Certification authority only for certain domains

Is it possible to make a certification authority certificate (even unsigned), which only allow to sign certificates for specific domain(s)?
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39k views

Chrome is telling me I am receiving a forged certificate for Gmail, is someone trying to hack me?

I went to log on to https://mail.google.com this morning and I got the following error. Is someone trying to attack me or is this just a bug? I'm on a WPA2 encrypted wireless connection using Chrome ...
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How to use OpenSSL generated keys in Java?

I have my pair of Public and Private keys and my certificate. Those where created in OpenSSL (why? because I was asked to do it in OpenSSL). Now I want to use those things to make a Java app that ...
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Dealing with expired or revoked signing certificates with Infopath documents

Suppose I have an Infopath form that is digitally signed today by a valid, and active user. When that user leaves the company, we disable the account and revoke the certificate. This causes a problem ...
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What damage could be done if a malicious certificate had an identical “Subject Key Identifier”?

I'm looking at the the Subject Key Identifier attribute of a CA certificate and am trying to understand the role it plays in validation and infer how validating client software could get it wrong. ...
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884 views

Adding custom data in X.509 certificate

I am using SSL with client authentication. I need to send some extra data while sending the client certificate? Can I send it in the certificate? Can I use the extension fields in certificate for that ...
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694 views

Two certificates on smart card

I have a question regarding Swedish gov eID (but I guess it is a pki/smart card general question); Why is there two certificates/keys on the card? Background: In Sweden you can have a "citizen ...
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ECDHE_RSA and gmail

I'm using Chrome on Ubuntu Linux to connect to Gmail. The connection info says that ECDHE_RSA is used for the https symmetric key exchange. Based on my understanding of TLS and Gmail, my client ...
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How can a certificate be valid in the Hybrid Model but not in the Chain Model?

All dates in European format! I am learning about validity models, but the solution for this assignment confuses me. Translation: The relevant data for the applicable certificates are shown ...
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208 views

What issues might exist with TLS-OBC's emulation of Browser Certificates?

TLS-OBC is an RFC proposal that increases SSL/TLS security by using certificates on both ends of the TLS connection. What's special here is that the client is permitted to dynamically create a local, ...
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612 views

google certificates correct CA [closed]

I view certificates of https://www.google.com.ua/ So I thought, when requesting via cURL, if I point by CURLOPT_CAINFO to those certificates (GeoTrust Global CA and Google Internet Authority G2 in ...
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481 views

Retrieving client certificate using Tcpdump results in zero length certificate

I am trying to proxy a mobile app (with Fiddler), which sends a client certificate to the server it connects to. I would think that capturing traffic with Tcpdump, retrieving the client certificate ...
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116 views

Authentication by Signing or MAC?

I'm still new to security, so I'm sorry if this question doesn't make sense or if I'm completely off base with something. I've got some messages I want to encrypt (probably with AES-256-CBC) and send ...
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833 views

How do I make or get computer certificates to use with IPSEC user authentication on Windows?

I am having trouble and need some direction using computer certificates with Windows 7 firewall IP Security rules, using certificates only for user authentication. I can get everything to work ...
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What is updated with “Update Root Certificates” enabled? What is the equivalent in Windows 2008R2?

What root certificates are/are not updated when the following checkbox is checked? Additional questions If I manually remove a root certificate, will this service replace that very certificate? ...
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Are SSL certificates from a CA necessary for secure communication?

Am I right in thinking that SSL certificates from a CA are purely for identification purposes and serve no purpose in the actual encryption of data? In other words if I were to create a self signed ...
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What data should I validate when validating X.509 certificates using Java?

Well I began with PKI a year ago with RFID system at school. Now I'm asked to implement this in my job. I understand most part of the idea. The doubt is about the certificate validation. I know it ...
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Is it possible to create a self signed certificate authority?

Would it be possible to create a legitimate certificate with the CA bit set? I dont have a usecase associated with this, I'm merely curious. To explain my question : Suppose I sign a public ...
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Internal SSL Certificates?

As a developer I really like the idea of using OpenSSL to get perfectly good, free, SSL certs. Unfortunately, from all the research/analysis I've done so far, it doesn't look like there is any way to ...
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What is an intermediate certificate authority?

What is meant by an "intermediate certificate authority?"
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Who is this strangely named Certificate Authority?

I'm researching certificate authorities, and I just have no idea what to think of the CA named x00Ax00-x00Tx00rx00ux00sx00tx00 x00Gx00ex00sx00.x00 x00fx00xFCx00rx00 ...
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How to distribute client certificates without exposing private key?

I'm desgining a B2B web service based on WCF. As the number of clients is relatively small and security is a priority, i have chosen to go with X509 client certificates for client authentication. I'm ...
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Is it possible to detect SSL private key changes?

I wonder if it would be possible to detect a change of an SSL private key? If you change the key, then I think one must issue a new certificate, but new certificates could be issued without changing ...
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How do you verify a certificate belongs to a domain?

I'm using PHP and trying to verify a SSL certificate belongs to the SMTP domain/IP I'm connecting to. Currently I can verify the certificate is valid using the following code $resource = fsockopen( ...
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Certificate Transparency

From what I read here, if the intermediate CA has been compromised, a fake cert can be issued and the privacy of the end-users could be compromised as well. In order to remediate this situation, ...
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206 views

How to verify certificate with very little information

Lets assume there is a server and a client and you want to connect those two. Server has a self-signed certificate, and prior to establishing the connection for the first time (enrollment) the server ...
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Are Windows Updates susceptible to tampering, eg. using a MiTM attack.

My real question is how are patches and updates authenticated in general. But for example how does windows know a windows update is really a windows update, does it just trust the URL or is there some ...
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What does it mean for a digital certificate to be “signed”?

When someone says that a particular digital certificate (like an SSL cert) has been "signed with a key", what does that imply? Does that mean the certificate simply includes a key that should be used ...
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407 views

Is possible that a TLS server send more than one certificate to the client for the same site?

What I'm trying to archive is enable ECDSA and DSS ciphers in my site, but at the same time not depend just of self signed certificates, so I could sent to my client more than one certificate and them ...
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Can the client certificate authentication process treated as a user digitally signed the content(and then get verified on the server)?

The authentication was triggered by certain event (like approving button) on the form. In the process of client certificate authentication (in IIS), user was asked to use their PIN (private key) and ...
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How powerful are top Verisign executives?

I believe that VeriSign has issued a big share of world's SSL certificates. Many corporations and governments use them. Is it possible for a person that has access to Verisign private keys to sneak a ...
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Does Authenticode still work offline and with a “fake” certificate

Here's our story: We're developing some software (written in C#/.NET) and we're already signing the assemblies with strong names, I do this in Visual Studio with a pfx file that is protected by a ...