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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IP address in SubjectAltName

Is it allowed to specify IP as DNS name for SAN certificate ?
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1answer
94 views

X.509 - How Is Certificate Chain of Trust “Subject Name”-“Issuer Name” Match Comparison Made?

I keep reading that in an X.509 certificate chain of trust that the "Issuer Name" in a certificate that has been signed by the Issuer must "match" the "Subject Name" of ...
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How should I sign a CSR using a signature created in HSM, in C# .NET Core? [migrated]

I'm exhausted after looking for an answer for 3 days. I don't know if my suggested flow is wrong or my Google skills have really deteriorated. My API needs to create a valid certificate from a CSR it ...
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1answer
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Are The ca Policy Values In the OpenSSL Configuration File Applied When Both Creating AND Signing Certificates?

Are the 'ca' policy values that are present in the OpenSSL configuration file applied when the 'ca' command is used to create a certificate AND when the 'ca' command is used to sign an existing ...
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1answer
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pfx file encryption algorithm

This seems like it should easily documented but I am unable to find. My c# code does this to create a pfx file. X509Certificate2 cert = store.Certificates.Find(X509FindType.FindByThumbprint, ...
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Where can I find a list of all government agencies with CAs in PKI root stores?

Is there a source that monitors popular root stores for CAs controlled by government agencies? There are several "root stores" that maintain a list of trusted root CAs. These root stores are ...
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1answer
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Where are field names of decoded human readable X.509 certificates specified?

The ASN.1 module for X.509 certificates as specified in RFC 5912 - Section 14 is as follows: TBSCertificate ::= SEQUENCE { version [0] Version DEFAULT v1, serialNumber ...
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3answers
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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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Are X.509 nameConstraints on certificates supported on OS X?

I have the following "chain" of certificates on a test machine right now: A self-signed CA cert, in my Keychain and trusted & trusted by Firefox. A CA cert with with the following, X509v3 Name ...
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Why does generating a self-signed X509 certificate not require my public key?

Let's say I have an RSA (2048) keypair that I generated private.key public.key For testing purposes I'd like to generate a self-signed X509 certificate. My understanding of a certificate is that it ...
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1answer
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How to fully view cross-signed certificate signatures

Long story short: Security scan raised a flag about a cert, found that it was an expired root on a cross-signed cert. Yadda yadda, updated intermediates, fixed issue. However, I noticed that openssl ...
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2answers
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Can public keys in digital certificates be used to verify name of certificate holder?

I recently had a conversation with a teacher who argued that in a digital certificate (x509), the public key is used to verify the name of the certificate holder. From my understanding, there are ...
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1answer
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Process and order of verification of a X.509 certificate chain

While going through the rfc5280 Certificate Path Validation to understand how the X.509 certificate chain is validated, I found out that the X.509 path processing Algorithm processes the chain in an ...
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x.509 certificate chain verification in Linux kernel prior to 4.12

I am trying to use certificate chain verification in Linux kernel. The purpose is to use IMA/EVM with public keys that are included in x.509 certificates signed by an own root CA. For this purpose I ...
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2answers
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Subject Alternative Name in Certificate Signing Request apparently does not survive signing

So I have been able to create a Certificate Signing Request with a Subject Alternative Name of the form subjectAltName=IP:1.2.3.4 by following the recipe in a previous (splendid) answer. When I ...
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openSSL shows a revoked certificate as secure

I downloaded a revoked certificate from the website https://www.ssl.com/sample-valid-revoked-and-expired-ssl-tls-certificates/. Specifically, the revoked certificate of the site https://revoked-rsa-ev....
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3answers
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Can X.509 Authentication be subject to brute force attacks?

I am working on an application (using Spring Security) that has two possible user authentication mechanisms: either X.509 certificate (using mutual SSL handshake) or user + password For user+...
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2answers
796 views

is the certificate signature a hash of just the public key?

Is the X.509 Certificate Signature an encrypted hash of just the public key or is it a hash of more then the just the key?
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1answer
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Migrate a x509 key using KSP (CNG) to CSP (CryptoAPI) in Windows

I have a code signing certificate issued to me by a commercial CA, and the key was generated on my local development machine using the new Cryptography Next Generation storage providers. ...
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2answers
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keyUsage Extensions on a Certificate Authority

I have a question about what key usage should I choose when creating a private CA (root or subordinate). I have inspected some root and issuing web certificate authorities and they tend to use ...
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1answer
346 views

Using NameConstrains in a CA certificate

I am trying to do something similar to what has been pointed out in this nice answer by Jonathon Reinhart. I have a CA certificate with Name Constrains (RFC): Permitted [1]Subtrees (0..0): ...
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1answer
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How does client verify the certificate provided by the server which is signed by different intermediate CA

I am creating a c++ secure client-server application using openssl library. I am still not clear about some aspects of the SSLHandshake procedure I have enabled Mutual TLS in-order verify the both ...
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Determine if private key belongs to certificate?

Given a certificate¹ and a private key file², how can I determine if the public key on the certificate matches the private key? My initial thought was to simply encrypt some text with the public key ...
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2answers
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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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How to set up OpenSSH to use x509 PKI for authentication?

I do not mean simply putting the public RSA key of a x.509 certificate into ~/.ssh/authorized_keys - I'm looking for a way to set up a ssh such that x.509 certificates signed by a pre-defined CA will ...
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Why don't folks seem to use ECC for TLS root certificate signature?

I looked around, and all I see is websites using RSA2048 for Root signature, and a few using ECC for encryption. Are there any reasons folks don't seem to use ECC for TLS root signature? Are there ...
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Why is /cacerts request necessary in RFC 7030 Enrollment Over Secure Transport?

In RFC 7030 Enrollment Over Secure Transport (EST) https://tools.ietf.org/html/rfc7030, the /cacerts request (Section 4.1 of RFC 7030) is used by the client to request the current CA certificates. The ...
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3answers
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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 does Cloudflare negotiate its server certificate?

When I access https://example.com on my company's laptop that has a X509 client certificate installed, using my home internet connection, without using a VPN, the requested page is signed using the ...
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1answer
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What are the sources of “SEC_ERROR_REUSED_ISSUER_AND_SERIAL” errors when using self-signed x509 Certificates in PKCS#12 files?

As part of an internal Client/Server application, I have created my own (self-signed) Certificate Authority (CA), as well as both Client and Server certificates signed by my CA. Loading my CA ...
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1answer
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How to add subject alternative name when converting PEM certificate to DER format?

Is it possible to add a subject alternative name when converting PEM certificate to DER format. openssl x509 -outform der -in Certificate.pem -out Certificate.der -extensions SAN -subject-alternative-...
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1answer
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When will CMP be part of OpenSSL? [closed]

CMP means Certificate Management Protocol. CMP for OpenSSL is currently a fork of OpenSSL. Do you know when it will be part of OpenSSL? https://github.com/mpeylo/cmpossl
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1answer
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openssl: does -keyform engine enables accessing TPM persistent handles with any key arguments ? Even with third party plugin like CMP?

If I use the tpm2tss-engine coupled with openssl, can I substitute, optionally any file path to a private key by a TPM persisent handle ? Will it work with extensions, like CMP for OpenSSL, for ...
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1answer
202 views

Differences in certificate verification between ssl libraries

I've been playing with x509 certificates to better understand them and I've hit a strange issue which makes me think I have a misunderstanding. Initially I tested everything with libressl 2.8.3 and ...
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1answer
126 views

Why generate dedicated issuer CA for TSU certificates?

I've observed the practice of generating dedicated issuer CAs for signing TSU (Time-Stamping Unit) certificates instead of just using another existing issuer CA, for example, one used to sign S/MIME ...
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2answers
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Client Certificates from Public Certificate Authorities

I'm looking into mutual TLS authentication for a B2B API. Is it possible to use mutual TLS authentication using X.509 certificates while relying on Public CAs? I see that some Public CAs (from CA/...
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1answer
152 views

Can I concatenate multiple x509 certificates?

I have a very large cluster I am building of over 100 nodes, there are various types but I will use the Elasticsearch nodes as an example. I am encrypting mesh connections between nodes with TLS. ...
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0answers
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OCSP invalidation of intermediate CA using OCSP_SIGNING

I'm implementing an OCSP server to answer OCSP requests for my custom CA. I already implemented the invalidation of leaves certificates, with the intermediate CA certificate signing the OCSP response,...
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0answers
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RDP with self-signed cert requiring password before launching display

I've noticed that the search engine Shodan grabs screenshots from hosts running an RDP service, even if they offer a certificate. To my understanding, the certificate is used to authentify the server,...
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1answer
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Attribute certificate to model subject-object-action for access control

I am using Attribute Certificate (along with X509 PKC) for access control. What I really want to model is an access control semantic where a subject has a privilege to perform certain action on ...
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2answers
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Difference between public key and private key validity period

In the section about certificate extensions, the ITU-T X.509 recommendation writes: The private key corresponding to a certified public key is typically used over a different period from the ...
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1answer
287 views

OPC-UA Certificate Handling

I am currently developing and extending an OPCUA-Server based on "node-opcua". The next steps would require to add certificate handling and that's also the point that makes me the most problems. My ...
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1answer
152 views

SSL certificate with IP

I have an embedded device and it is running a https server. This device will be accessed from a standard web browser using the IP address. I am generating a TLS certificate. I have added a commonName (...
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4answers
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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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1answer
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What is required to verify that an x509 cert matches a key?

Imagine that we have an x509 cert (if it matters, in .pem format) and a key supposed to certified with it. How can I validate, that the cert certifies exactly that key? My impression is that it is ...
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1answer
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Which properties of a X.509 certificate should be critical and which not?

RFC5280's section 4.2 states Each extension in a certificate is designated as either critical or non-critical. A certificate-using system MUST reject the certificate if it encounters ...
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Can you make a device certificate expire after the root certificate?

I have created a CA root certificate and a device certificate to go on my device signed by the CA certificate. My question is as follows: Can you make the device certificate last for 30 years, and ...
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2answers
8k views

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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2answers
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If you revoke a certificate authority's certificate, do all of the certificates it issued become invalid as well?

If you revoke a certificate authority's certificate, do all of the certificates it issued become invalid as well? What about for certificates issued by an authority beneath it? For example, if root ...
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Can a revoked certificate be re-instated?

If a certificate is revoked, can it be re-instated, or is the only option to generate a new one?

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