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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Distrusting a cross signed certificate

Consider the following scenario OpenSSL and x.509v3 is used. You have 2 CA's: CA1 and CA2. Both CA's have cross signed each other, meaning CA1 has signed CA2 and CA2 has signed CA1. When CA1 signed ...
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How to create and embed Signed Certificate Timestamp (SCT) in certificate

I have deployed a Certificate Transparency (CT) log server that uses Google's CTFE (named "certificate-transparency-go" on Github) and Trillian Projects. And I have issued a pre-certificate, ...
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What can happen if lifetime info is not included into an X.509 certificate?

When a certification authority generates a signature, but if the message to be signed does not include the lifetime information (period of validity), what can happen in terms of security being ...
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ChaCha Single-Use RNG with All Zero Plaintext + Nonce

I am creating an internal application that will be used to generate and manage self-signed certificates and certificate authorities. Its primary use will be for generating certificates used in SSL ...
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Name Constraints, empty sets in permitted subtree (RFC 3280 vs RFC 5280)

I'm trying to understand the effect of empty sets in permittedSubtrees in both, RFC 5280 and RFC 3280. There is something that doesn't compile in my head. Scenario: We have a CA certificate with the ...
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What happens when you ignore HTTPS warning?

I’m setting up a router at home, and I just created a CA and signed a cert with it. The first time I navigated to the router console, I was greeted with the familiar scary Safari warning about ...
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What is the best practice for relying parties to selectively trust certificates in a corporate pki hierarchy?

I have a pki infrastructure for internal company use. In this pki there are multiple registration authorities whose responsibility is to. receive certificate issuance requests verify the identity of ...
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application of key usage extension

I understand how Key Usage Extension of x.509 certificate works. I have gone through the Key Usage section of RFC5280 and I know of all the valid values and what they mean. But what I don't understand ...
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How can I recover the full certificate chain knowing the final X.509 certificate?

Given Final X.509 certificate A in PEM format. Access to the certificate store of the server, which encloses all certificates, including singing chain for the certificate A. OpenSSL shows following ...
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Can an EAP-TLS Server X.509 certificate authenticate an mDNS Avahi/ZeroConf/Bonjour name?

Using an internal CA, can valid X.509 certificates be created for mDNS domain names (as distinct from conventional DNS domain names)? E.g. a hostname like radius.local? Would such a certificate be ...
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Best practice for "stateOrProvinceName" in certificate

In RFC-4519 stateOrProvinceName is abbreviated to ST. Should we assume that it is best practice to put ST=<name-of-state> in the certificate if the state or province is indicated? After all X-...
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Is it must to have "Key Usage" extension in the selfsigned root certificate?

I have gone through multiple questions but still I am confused. RFC X.509 also does not clarify it. Conforming CAs MUST include this extension in certificates that contain public keys that are ...
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How can I prevent non-SAN TLS certificates from bypassing name constraints?

I'm trying to create a private CA and want it to only be able to issue certificates for my domain via name constraints. However, even if I create the CA with restrictions on DNS names as well as ...
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How to protect private key for client cert in machine store? Is it acceptable for it to be exportable?

Is it acceptable to store a client cert's private key as exportable in the computer's certificate store? I have a .NET desktop app that installs client certificates in local machine\personal. The ...
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Why do the X.509 certificates need the public key?

I am currently reading about X.509 certificates from RFC 5280 and there is a thing in section 3.1 that I cannot understand. It says: Users of a public key require confidence that the associated ...
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Difference between -CAfile and -trusted in OpenSSL verify

openssl verify can be executed with both flag -CAfile <FILE> and -trusted <FILE>. The explanations from OpenSSL 1.1.1 manual: -CAfile <FILE> A file of trusted certificates. The file ...
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Role of public and private keys of client certificate in mTLS [duplicate]

I'm curious to know how mTLS works in more detail in regard to client authentication. Firstly, I issued 3 certificates: root CA, server and client. The last two are signed with the root CA. Secondly, ...
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Client authentication using X509 certificates behind the scenes

In my application I've successfully implemented client authentication using X509 certificates Here's what I've done: Issued a self-signed CA root certificate with a private key Issued a web-server ...
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Why does Microsoft SmartScreen require OV certificates to be signed by a trusted CA?

Signing your applications with an OV code signing certificate enables them to build reputation together in Microsoft SmartScreen, rather than each binary building reputation separately. This allows ...
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Avoid re-encrypting persisted cipher texts when using certificates

An application uses RSA to encrypt small texts before persisting in database, using public key of the end node of the application. Only these end nodes must be able to decrypt thge ciphers and only ...
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mTLS Client Authentication by Signing Arbitrary Message using Browser

this is my first post here in the area of ​​security and encryption. I will try to be succinct, and let you know that I am not an expert in security. Context: My client (visitor) has an X509 ...
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Hot to validate X.509 Certificate [duplicate]

A client wants to show a stream of his Motobix Webcam on his website. Its easy to show a jpg stream. But the problem is: The stream source is not protected with a valid ssl certificate. On the camera ...
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Can a SHA2 x509 cert thumbprint be spoofed/specified?

Looking at a potential solution where the thumbprint of a client cert is used to identify individual users and provide access control. Supposing someone was able to view the thumbprint of a cert ...
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What happens if one certificate path is valid while the other one is not?

I have recently figured out that Lets Encrypt provides "invalid" certificate chain in it's certificates that are pointing to the root certificate that has expired a month ago (they did it ...
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X.509 certificate's signature algorithm vs. algorithm used in key derived from it to verify a signature

I have the following from Google's public certs for verifying JWT ID -----BEGIN CERTIFICATE----- MIIDHDCCAgSgAwIBAgIIW4K0b18ff70wDQYJKoZIhvcNAQEFBQAwMTEvMC0GA1UE ...
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Why my certificate does not have OCSP must-staple extension even when CSR contains it, is OCSP must-staple still used?

We received recently security report with [low] security issue: Missing "Must-Staple" extension on certificate. With help of old article oscp-must-staple I managed to create CRA with ...
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How should I securely rsync to a host with a self-signed certificate on a private network?

I have a backup server that has a self-signed certificate (x509) and another server on the same network. I would like to rsync data to the backup server from the other server. However, I prefer not to ...
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How best to cryptographically sign scientific papers?

Academia has had some high profile cases of forged identity; for instance, in the last decade the publisher Springer has had to retract 62 papers for this reason alone. Usually these aren't high-...
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Ramifications of including "localhost" in the subject alternative field of a x509 certificate?

Are we inviting any problems if we add localhost and 127.0.0.1 to the subject alternative name field of an x509 certificate? We are still trusting the appropriate root CA, but relaxing the rules of ...
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How to reliably identify a certificate as intermediate certificate?

As per the title, is there a way to reliably identify a certificate as an intermediate certificate? I can identify if a certificate is a root certificate. But i can not tell the difference between an ...
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TLS: Verify server certificate before sending client certificate?

I am wondering if there is any harm in having a TLS client send its certificate to a server before having established trust with that server. I have found a similar question, however that mostly ...
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Software signing : multiple certificates

I'm quite new to the cryptography field, and I'm trying to understand a few things: I used binwalk on Linux to analyse Minecraft.msi, and I found multiple certificates in the .msi See below: I'm ...
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Is the RSA Public Key size always the same as the private key size? [duplicate]

When working with x509 certificates and a public and private key pair, let's say you generate a private key that is 4096 bits. Is it possible to have a public key that is only 2048 bits then? Or are ...
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How may I check if an expired certificate was valid at the time?

I have an old let's encrypt (but disregard that, it could be any) certificate that is no longer active. How may I check if it was valid at the time?
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Do X.509 Certificate Serial Numbers Change When A Cert Is Renewed?

Do X.509 certificate serial numbers change when a certificate is renewed? I understand the thumbprint changes, but I am unsure about the serial number. I suspect so since it's a new cert, but if you ...
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What sort of RSA private key format is this and how are they generared [duplicate]

I am used to seeing a regular private key, with the standard key block, but I just came across this type which carries extra information as you can see. What format is this and how are these generated ...
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Obtaining .p12 certificate from PEM file and CRT file provided by GoDaddy

A few months ago a colleague who left generated a CA certificate from GoDaddy. I am not sure the exact steps he took but currently we would like to install the CA certificate on a server to fully ...
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x509 validation check service

I would like to check validity of x509 certificates of my clients. I would like to trust the certificates what big companies trust. For example I would like to trust what Microsoft Edge, Chrome ...
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Key differences between X509 TLS Client certificate and server certificate

Is there any difference between a X509 TLS client cert and a server cert? I had been implementing certificate-based mutual authentication and hence trying to get/use certificates for IoT devices. ...
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Generating a DER-encoded DSA public key of a particular file size

I am reverse engineering a binary that contains a raw, DER-encoded X.509 certificate containing a DSA public key. I want to replace this certificate with one that I have generated so that I have ...
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How to verify a x509 certificate from Apple on a Ubuntu server?

I'm trying to verify GameCenter authentication on an iOS app with GameKit. The fetchItems API returns a URL for the public key needed to do this. Steps 3 and 4 of that API say: Use the publicKeyURL ...
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Is it possible to use X509 to verify other information, like a vacination?

Background: Germany has decided to implement the proof of vacination for Corona based on 5 Blockchains. It's supposed to be anonymus and safe and the verification could hapen with a QR-Code. My Idea: ...
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Windows X.509 certificate private keys lost

Have the same certificates installed on several machines, but this happens on only one of them. The certificates are self-signed certificates. The certificates are used for WCF message security. ...
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Can a man-in-the-middle replay a valid X.509 certificate? [duplicate]

Consider the following scenario: M (who will later be the man-in-the-middle) connects via https to bank.com. He saves the X.509 certificate (or certificate chain) received from bank.com. Alice ...
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Exporting a JKS entry to X509 certificate - why public key differs?

There is a JKS file containing an entry named "mycert": https://filebin.net/l93faa9qa3rkt32h Password is test123 Based on the following screenshot, mycert has a public key (RSA 2048 bits) ...
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Is it possible to update the contact info (FN/LN, OU, Organization,..) of a certificate?

When creating a self-signed certificate you are asked to enter some information (First Name, Last Name, Organization Unit, Organization, City, State,...). Is it possible to update any of those fields ...
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openssl SubjectDN parameter, abbreviaton of argument keys and how to add extra ones

openssl command allows to create x509 certificates, and to add subjectDN using the -subj parameter. The parameter accepts a string of slash-delimited values in the form of: "/...
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X509 certification and communication

I am having trouble understanding the concept of X509 encryption and its application to web service communication. The situation is that I (client) would like to communicate with another party (server)...
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Real world X.509 v2 certificate examples?

Just out of curiosity, could you provide (old) real world X.509 v2 certificate examples that include the deprecated (in some version of X.509) and forbidden (in RFC 5280) issuerUniqueIdentifier or ...
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What client-cert validation can be gleaned from DNS/reverse DNS lookup?

I'm learning about X509 certs used in client-cert authentication to https endpoints. I have a nice Python script that checks many facets of the client-cert. Is there any validation that can be ...

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