X.509 is an standard for a public key infrastructure used for authentication and access control. X.509 specifies standard formats for certificates, revocation lists, attribute certificates, and path validation.

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Trusted CA / smart card authentication on Ubuntu

For SSH connections, I want to validate a smart card certificate against a trusted CA and CRLs. I found tons of documentation on how to enable smart card authentication but most of them focus on ...
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Can a SSL certificate have longer validity period than its parent in X.509 chain?

When a X.509 certificate chain is composed of X1, X2 ... Xn and Xn is root CA, Can a certificate in lower level have longer validity period than its parents? I think that lower level should be proper ...
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Restricting Issuing CA's choice of keyUsage and extendedKeyusage

I am currently designing a private PKI for my family and some close friends for use in E-Mail, VPN, file sharing etc. The PKI will be 3-tiered: Root CA -> Policy Authority -> Issuing Authority ...
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832 views

How long can X.509 certificate chains be?

Usually, I only see certificate chains with a root CA, an intermediate one, and a third one for the particular SSL/TLS website; but can X.509 certificate chains be deeper than 3 levels? Is there a ...
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84 views

Can Passpoint X.509 certificates be used to MITM SSL connections on Passpoint networks?

Passpoint/Hotspot 2.0 public networks like LinkNYC require users to install X.509 certificates, for EAP authentication. Can these certificates be used by the provider to execute man-in-the middle ...
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34 views

Questions regarding CRLs (producedAt and not modified)

I have two questions regarding the safety of requesting CRLs. My first question is: shouldn't CRLs contain a producedAt field just like OCSP responses? This would make sure a hacker doesn't send an ...
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27 views

Can there be two certificates with a same serial number in the world? [duplicate]

Recently I came across this odd question. I hope, Serial number is unique across certificates signed by a particular CA. So is there any chance that two different CAs sign two different certificates ...
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101 views

Sign GnuPG master key with own X.509 certificate?

Can I use a trusted X.509 digital certificate to facilitate the expansion of my personal web of trust? To be more specific: Can I use my X.509 certificate to sign my personal GnuPG master key? Will ...
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105 views

TLS - How to know a CRL URL is not changed

If a hacker would manage to sign a certificate with a stolen (private) key of a CA and would remove or change the URL in the CRL Distribution Points extension, and later the certificate would be ...
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113 views

When can I commit an OpenSSL Certificate (.pem) to source control?

That is to say, in what cases does it make sense to commit .cer files, or a stack of .cer files in a .pem, to internal source control like SVN or Git? If it's just a list of signed public keys, I ...
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35 views

For X.509 Certificates where is the actual digital signature?

When you open up the certificate information from your browser and go to the details tab there is a bunch of information for various certificate fields. I am wondering which field contains the actual ...
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71 views

Does X.509 standard claim to check client certificate's expiration date on server side?

Does the X.509 standard claim to check client certificate's expiration date on server side? Consider an expired client certificate in the trust store of web server. If some client tries to ...
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Does TrustManager PKIX (or RFC 3280/X.509) really check client certificate expiration date?

It was noticed that default java implementation of TrustManagerFactory for PKIX trust manager algorithm (X509ExtendedTrustManager) doesn't really check expiration date of client's certificate during ...
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44 views

Which CRL should an intermediate CA crlDistributionPoint contain?

Given a root certificate authority (CA) and an intermediate CA signed by the root: Which CRL should the crlDistributionPoints contain to for the intermediate CA? The root CA's CRL or the ...
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1answer
42 views

Role of X.509 in signature verification

My requirement is signing the message with private key on one side and verifying it on other side using public key. SHA256, rsa:2048 are the algorithms i need to use. May i know whether X.509 is ...
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822 views

SSL/TLS Certificate Update?

We had a setup which used openssl0.9.8 so it had only support for SSLv2 and TLSv1.0. We had a script which generates self-signed X.509 certificates and uses openssl library. Now we have upgraded ...
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285 views

Gmail X.509 certificate chain

I have asked about this on several forums but never got a straight answer. If the root certificate on a certificate chain has a different fingerprint to the root certificate available for download on ...
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1answer
73 views

Cross-certification between worlds like X.509 and PGP?

Sometimes it can be advantageous to use existing trust relationships in one certification world - X.509 or PGP - to create trust in the other world. At the lowest level I can always take an X.509 cert ...
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28 views

Validating the ROA certificate

Suppose I have a system, where the server requires the clients to attach their ROA certificate to prove that they have the right to that IP Prefix. Now if the client attaches the ROA certificate ( ...
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39 views

TLS Certificates only for Clients

I'm aware that sites like StartSSL use Client-Certificates, I opened mine in Firefox and it showed me: "SSL-Client-Certificate", "E-Mail-Receiver-Certificate", "E-Mail-Signer-Certificate". Now I'm ...
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1answer
117 views

Limiting a CA to only issue valid certificates to internal web sites and clients

What are the possible defense measures that can be applied to a simple PKI (no intermediate CAs, etc.) used to authenticate clients and servers over TLS on an internal network only? Certificates ...
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1answer
160 views

Security Structure of an API

I've been developing a web application and APIs for 8 months. I implemented OAuth 2.0 client credentials for authentication. And now I have to implement TLS to my APIs. I've been dealing with SSL/TLS ...
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1answer
939 views

Is Man-In-The-Middle necessary for a CA to read HTTP plaintext?

Although I understand the basic theory behind certificates and asymmetric cryptography, I'm not quite sure on the details of the X.509 protocol. I'm wondering what attacker model a given CA requires ...
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784 views

What is the difference of TrustManager PKIX and SunX509?

Java's JSSE provides two different TrustManagers: PKIX and SunX509 I tried to find out what the differences between both are, but couldn't find any in the documentation. Can you tell me the ...
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2k views

Relationship between RSA, Diffie-Hellman Key Exchange, PKI and X.509?

I am getting confused with RSA, Diffie-Hellman Key Exchange, PKI and X.509v3. I took a look of RSA's mathematics algorithm, it seems like a encryption algorithm, right? Generating public key and ...
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Sign PKCS#7 and verify PKCS#7 signature with OpenSSL

If someone have to transfer X.509 certificates in a single bundle, usually, it is recommended to pack them into PKCS#7. And content of PKCS#7 can be signed. OpenSSL allows to pack certificates into ...
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181 views

Why do private networks use both X.509 and User/Password authentication

For example, the school network I am on requires both a name & password to log in along with having its X.509 certificate installed in my browser. Why does it need both? Shouldn't name and ...
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280 views

How to determine if an X.509 certificate is a renewal of another known certificate?

In my application, the human user accepts the server's X.509 certificate, verifying the fingerprint during the first-time connection. The fingerprint is stored in the client software. At later ...
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540 views

cross-signed end-entity certificates: usage in apache/openssl/gnutls

A previous question, What is the use of cross signing certificates in X.509? described cross-signed certificates well. I have a situation where the clients trust CA1 xor CA2, and both need to reach a ...
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What's the difference between X.509 and PKCS#7 Certificate?

Am I correct calling file with .p7b file extension saved as 'Cryptographic Message Syntax Standard - PKCS#7 Certificates (.P7B)' in Windows - a 'PKCS#7 certificate'? Or is it better called 'X.509 ...
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362 views

The reason to insert Subject Alternative Names into CA certificate

I am trying to understand meaning of the Subject Alternative Name extension. The reason of usage it in SSL X.509 certificates or other end-entities certificates is mostly clear for me. However, I ...
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697 views

Self-signing client certificates and distributing them, is the following a sound procedure?

I have a case at hand as follows: There is a number of clients in Internet (i.e. untrusted channel), initially in hundreds but growing in numbers. There is a server doing processing related to these ...
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1k views

How to safely renew user and CA certificates in a PKI

I am currently developing my own PKI where x.509-client-certificates are issued by a public server. At the moment, the CA-public key is distributed with the binary and there are no routines for ...
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578 views

What is the difference between openssl and mkcert and IIS self signed certificate

What is the difference between openssl and mkcert. Which one should I prefer. I want to create an IIS hosted WCF service. Which one should I use to create an SSL certificate. Also, there is another ...
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305 views

determine X.509 certificate class

I am very familiar with OpenPGP but don't even use X.509 / S/MIME. I know that there are several classes for certificates (from email check to personal ID check). I would like to know how you ...
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906 views

Do SSL / X.509 certs cover all ports for a host?

Or are certs both host- and port-specific (excepting wildcard certs)? I would assume they aren't, because they're supposed to verify a domain, but at the same time I've never seen anyone run HTTPS on ...
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311 views

How to encode a username in PKIX certificate?

I was reading through RFC 5280, PKIX Certificate and CRL Profile, Section 4.2.1.6, Subject Alternative Name: The subject alternative name extension allows identities to be bound to the subject ...
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675 views

Can a certification authority sign another CA's certs?

Disclaimer: I have low knowledge of X.509 and PKI, so I would appreciate an answer that is not entirely technical, i.e. by using real-life example scenarios.) I was searching for information ...
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286 views

Certificate request - why does the requester have to create a private key?

If remember right, then before I send a CSR (Certificate signing request) to the CA, I have to create private and public keys. Then I use the public key to encrypt my personal details before I send ...
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Kohnfelder Certificate [closed]

The Kohnfelder certificate standard is very similar to that of X.509 certificate standard. Comparing the two standards, does one have an advantage edge over the other? or what are the pros and cons of ...
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412 views

can a x.509 certificate alone be used for user authentication?

we have a scenario for implementing SSO using x.509 certificates. A secure client will download a x.509 certificate (only certificate...no private key is available) upon user logs into the windows ...
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4k views

Certificate verified using two different paths

StartSSL has an intermediate certificate that they use to sign their EV certificates: sub.class4.server.ca.pem. This certificate's issuer is shown by openssl x509 to be /C=IL/O=StartCom ...
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Deploying software that requires X.509 certificates

I have a self-hosted WCF application, with a server application running on the server (obviously) and a client application that will be installed on the users PC. Up until this point I have been ...
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Why do public key certificate “Trust anchor”? Does this introduce a single point of failure?

When you look at currently used concept of Root CA (primarily in SSL/TLS context), you can see a single-point-of-failure vulnerability, which means, if your private key is disclosed, you automatically ...
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384 views

Can anyone explain how to use an X509 client certificate to securely authenticate a user?

Bit of background. Web Application that can generate Pub/Priv Keys and X.509 certificates. How would I make use of the certificate in a web application, username and password login form to provide ...
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5answers
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inquiry about SHA1 with RSA for certificate signature

As you all know, plenty of X.509 Certificates use (PKCS#1 SHA1 with RSA encryption) as the Certificate Signature Algorithm for generating the signature of 2048 Bits long. We know that SHA1 hash ...
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Is is typical to create both x509 and OpenPGP key pairs?

I'm looking into increasing my use of signed and encrypted "things" - LibreOffice Documents, Off-the-record chat, PDFs, emails, etc. I'm finding that some things only support x509 format-certificates, ...
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1answer
1k views

How is an Authenticode timestamp verified?

For an Authenticode signed file to be verifiable by Windows after the original signing certificate has expired (typically 1-3 years after issue), the file also needs to have a cryptographically signed ...
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Choosing the right X.509 certificate infrastructure for securing LAN communications between a PC and a device

Edit: seems like I was quite hasty when typing in my question at first, so here is an updated version of it. I am developing an application that runs on PCs which are on the same LAN as other ...
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user identity certificate

I want to create a new scheme for user identification, like X.509 certificates, but not X.509. Is it possible to use this new certificate over the existing Internet? and if yes, what are basic ...