Questions tagged [x.509]

X.509 is a 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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How to get public prime from DHE from TLS v1 DHE-RSA x.509 certificate?

I can view the certificate using openssl s_client -showcerts -connect www.masaood.com:443 </dev/null I can view the public key of a RSA, but cannot find any information for DHE: openssl ...
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X.509 Why is the signature algorithm added twice in the Attribute Certificate?

As I read some parts of the X.509 specification I found the signature added twice - first in the AttributeCertificate as signatureAlgorithm and second in the AttributeCertificateInfo as signature. ...
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Verify that a second TLS connection comes from the same client

I would like to implement kind of a trust-on-first-use (TOFU) scheme with TLS: A client creates a key and a self-signed certificate. The client connects to the server with this certificate. The ...
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WPA2 Enterprise EAP-TLS Key Exchange

I'm in the process of implementing 802.1x WPA2 Enterprise Authentication using FreeRadius and EAP-TLS (Mutual TLS Cert Based Auth). I am keen to understand how to actual protocols work together and ...
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X.509 certificate renew vs. rekey

What is the difference from CA perspective between renewal and rekeying of the certificate previously issued by this CA?
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RSA or ECDHE for key establishment?

Recently, i have been looking at PKI and certificates, and TLS 1.2 as part of my study of cryptography. I have the understanding that the public key included in the certificate of a website is the key ...
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RSA or ECDHE for x.509 certificates-what does each do?

I am relatively new to x.509 certificates, but recently i have been looking at the https connection padlock at the top of the screen. On certain websites, clicking on the pad informs me that the site ...
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Missing X509 extensions with an openssl-generated certificate

My goal is to create a certificate with opensslsimilar to this one generated with cfssl Certificate: Data: Version: 3 (0x2) Serial Number: 60:44:dc:0d:80:f4:54:55:e8:...
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Could governments and banks become CAs?

When you apply for a passport, driver's license, home mortgage, bank account, credit card, etc., the issuing organization must verify your identity. In the course of doing so, would it be feasible for ...
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How are ECDSA signatures computed for X509 Certificates?

I am trying to verify a certificate signature on my own. To do this, I created a self-signed certificate using OpenSSL with the two following command lines: openssl ecparam -name secp256k1 -genkey -...
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Using short hostname in X509 certificates

We are using an internal Certificate Authority for our company. We noticed that it is possible to add as subjectAltName the hostname without the domain. We are using example.org for internal servers ...
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OpenSSL Verify: Difference Between “unable to get issuer certificate” and “unable to get local issuer certificate”

From the man pages: 2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate the issuer certificate of a looked up certificate could not be found. This normally means the ...
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How to restrict a X509 certificate to be used only for a web server

I would like to restrict the X509 certificate for a site to be used strictly for a web service, as opposed to code signing or certificate signing. Which basicConstraints and keyUsage usage attributes ...
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Does openssl refuse self signed certificates without basic constraints?

I have two extremely similar self signed certificates, generated via two different methods. To test them I have: Added an entry in my hosts file for local.mydomain.com Set up an nginx server to ...
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Can I revoke a CRL-signing certificate by using split CRLs?

I'm setting up an X.509 certificate authority that will issue only three types of certificate: Subordinate CA certificates, CRL-signing certificates, and OCSP responder certificates I'm interested ...
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What's the difference between “Public Key Algorithm” and “Signature Algorithm” in OpenSSL output?

If the output is:- ➜ $?=0 % openssl x509 -noout -in ./cert -text | grep Algo Signature Algorithm: sha256WithRSAEncryption Public Key Algorithm: id-ecPublicKey Signature ...
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Certificate chain mantainance [closed]

According to standard rfc5280 , when user wants to validate a certificate, one step is to build a certificate chain, then check whether it is complete. I understand the idea to make a list to ...
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One certificate for both client and server authentication

Is there any reason why I shouldn't issue end entity certificate with both TLS Web Server Authentication and TLS Web Client Authentication? What should happen if the client certificate which should ...
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Certificate verification worries

I am having trouble getting a SSL connection to work. I did a lot of research on the web, but i am still missing some understanding it seems. I hope you can help me. I generate a development ...
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Testing Digital signature on an incoming request via Apache

I am creating an API endpoint that receives payload from a third party. The third party is signing the request with there X509 Certificate(Private Key). I have been provided with their Public ...
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How issuer's certificate is found to verify a given certificate?

I'm trying to understand how digital signing using x509 certificates works. I read a few articles and related answers on the web, but still there are a few questions left to confirm my understanding: ...
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Reason for Subject name in an X.509 Certificate

For my studies, I'd like to dive a bit deeper into PKI and X.509. Talking about certificates, one always gets the following sentence: "Digital certificates map public keys to entities" This means, ...
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Where is the version number in an x509 version 1 certificate?

I'm parsing x509, versions 1 and 3. I found the version field in the v3 cert, but I have two v1 certs (one from my organization, one I generated via OpenSSL) and in both of these the first non-...
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Certificate Validation [duplicate]

Sorry if this has been asked before, but I couldn't find an answer anywhere. Maybe I overlooked something, but I just can't wrap my head around how certificate validation works. This post details how ...
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Who was in the first set of CAs

I am currently digging into the history of SSL/TLS. I found that netscape introduced SSL around 1994/1995. They obviously decided to go with a X.509 PKI to mitigate MitM attacks. I, however, could not ...
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Is there an imbalance of issuer and responders in OCSP verification?

I'm trying out OCSP verification, and I'm not sure I'm following all that's going on. The requester can send 1-N certificate IDs, each has issuer hashes/serial no. The responder generates the counter-...
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How to properly create and use cross-signed CAs and certificates

I'm trying to create an environment with cross-signed CAs, and verify a certificate issued against one of the CAs, all using openssl. The best I got so far is getting openssl into an endless loop ...
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How TLS certificate chain is verified

Assume the verification of a TLS certificate chain. Suppose the chain has certificates A-B-C-D where D is the root certificate and A is signed by B, B by C, C by D. Suppose the intermediate ...
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1answer
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Establishing trust between a device and a developer, TLS signal vs X.509, GnuPG (or both)

Let's say you wanted to implement a "secure sideloading" mechanism for your embedded device so that the device could establish trust with authorized 3rd party developers. Developers would have local ...
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Why are there leading 0x00 bytes in the subjectPublicKey field of a DER X.509 cert?

For a simple example, I'm using a 512-bit RSA cert to illustrate my question. The cert can be found in both DER and PEM form here. I've been going through the certificate using this ASN.1 decoder (the ...
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Why one should prefer EST protocol instead of SCEP?

For many years SCEP was a simple and widely used protocol for obtaining X.509 certificates. However, not too so long ago another protocol called EST (RFC 7030) was developed. What are the main ...
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Is it secure to distribute Certificate Revocation Lists over HTTP? [duplicate]

I'm still trying to understand the functionality of a Certificate Authority, so if this obvious, I apologize. I understand CRLs play a role when the CA wants to invalidate a certain SSL certificate. ...
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1answer
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Generate Subject Key Identifier by hand using openssl command sequence

When creating a signed certificate I get the lines inside the certificate that identify the keys used: X509v3 extensions: X509v3 Subject Key Identifier: D8:D7:3F:99:CC:D7:20:AF:62:31:...
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Firefox refuses to use X509 certificate, complaining “Cound not verify this certificate for unknown reasons”

I stumbled upon this question and answer. I have the same problem as the OP, and am sorry to report that the proposed answer does not resolve it. Certificate in question has been verified by OpenSSL-1....
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Certificate based Access Control for Pub Sub messaging

I'm extending an existing p2p/master Pub Sub framework to support additional security measures, via over the wire encryption and topic based access control. I'd like to use the x.509 certificates that ...
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Why would I need to use the PRIVATE key to verify a file signature?

I use JavaScript to open CAPICOM store to choose certificate. After that I export selected certificate, public key and private key of that certificate and put them in three hidden fields. var ...
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Trusting the “subject” of an x509 certificate

A bit of background. Our organization is working on a document format that will be ingested by our software. We're using the CMS format to verify the integrity (by validating the signature). The CMS ...
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What advantage would someone gain by installing my root certificate?

The answer to this is probably simple, but it eludes me. Here's the scenario: At the moment, I have a server with a certificate issued to it using HTTPS that a customer POSTs responses to after ...
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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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3answers
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Is it possible to prove that a TLS server key has changed?

I know of a site that is currently using SSLv2 and I'm refusing to connect to them until they Disable SSLv2 Re-key their servers I'm insisting on #2 because due to DROWN, servers running SSLv2 ...
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Extract X509 client certificates from TCPdump files

I have the following question: assuming I have a TCPDump file containing a number of HTTPS connections using TLS mutual authentication, is there a way to extract all client certificates sent to the ...
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Java / Android Client-Server application. Digital certificates and CAs

I'm currently developing an application for Android that will allow users to back up their data on a server, which I am also developing in Java. I've pretty much completed the development of the ...
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1answer
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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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Use openssl to individually verify components of a certificate chain

This is related to another question, How to verify a signature of one entity by another using OpenSSL CLI? I used openssl s_client -showcerts -connect www.google.com:443 to collect three certificates ...
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How to verify a signature of one entity by another using OpenSSL CLI?

I'm teaching a class about certificate chains, so I download the chain from www.google.com which has 4 certs. I want to demonstrate how the dependencies work from issuer to subject by showing that ...
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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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Can a CN-only certificate bypass a name constraint if the CA goes rogue?

I am trying to cross-certify an internal issuer certificate, adding a name constraint for our domain. However, it seems that an attacker could bypass this protection by putting the desired host name ...
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Finding the EMSA-PKCS1-v1_5 DigestAlgorithm field in the x509 certificate

From the RFC - https://www.ietf.org/rfc/rfc3447.txt A.2.4 RSASSA-PKCS1-v1_5 For each OID, the parameters field associated with this OID in a value of type AlgorithmIdentifier shall have a value ...
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Why don't banks sign their email using S/MIME?

If email sent by my bank included S/MIME signatures that my mail client can verify, then I would have the assurance that the mail was not tampered with or sent by some malicious third-party. Most ...
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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 ...