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Questions tagged [certificates]

A certificate consists of a public key and information about the owner (e. g. the name of a person or server).

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57 views

Do people sign my subkey?

So, I've generated my GPG key pair. Created a subkey for signing and a subkey for encryption. Exported the whole thing, removed my master key pair to a secure place, re-imported only the subkeys. Now, ...
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630 views

Are any Certificate Authorities using 4096 bit keys for their intermediate and root certificates? [closed]

Are any Certificate Authorities using 4096 bit keys for their intermediate and root certificates? I know you can, of course, use a 4096 bit key for your server certificate, but I usually see 2048 bit ...
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1answer
45 views

Shortest Path for Certificate Network

I was reading an example from my textbook about verifying a certificate from a client using a certificate network. The example in the book is as follows: A issues a certificate to B. A issues ...
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2answers
719 views

Could someone reuse client certificates?

To my understanding, if a server “cert+key” (RSA) is compromised, than the SSL/TLS network traffic can be decrypted. What about a client “cert+key” (RSA)? Could someone reuse client certificates? ...
2
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1answer
177 views

Creating certificate: Where is my private key stored?

I have some problems to understand the storage of my private key when a CA generates my key pair. Let's assume the CA creates my key pair, issues the certificate with my public key and signs it with ...
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3answers
2k views

X509 certificate

I am studying the X509 certificate structure and here is an OpenSSL configuration file for generating the certificate. ("sth" just mean the actual string is removed) ...
2
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1answer
76 views

What key is used to encrypt the certificate and certificate verify message in TLS1.3?

Which key is used to encrypt certificate and certificate verify message in TLS1.3? I could not figure out which one it is reading section 4.4.2 of RFC 8846 and I only saw a vague mention on page 11.
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1answer
73 views

CAs are pre-loaded on the system, but how is it able to get intermediate certs?

I have the following X509 certificate: ...
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2answers
1k views

Parsing of X.509 certificates

I'm working on a firmware for a platform with limited resources with C as programming language. There are a set of cryptographic primitives to be implemented, including AES, GCM/GMAC, ECDSA, ECDH. ...
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1answer
697 views

Can I apply “encrypt with public key and decrypt with private key concept” using ECC certificate?

If Alice wants to send encrypted message to Bob, she can use Bob's public key to encrypt the plain message. Once Bob reliably gets encrypted message, he can decrypt it with his private key. In this ...
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3answers
87 views

Is there a method/protocol to validate a self-signed certificate by comparing a shortened hash?

I'm working on a solution where an iPad should connect to a server software running on a laptop using TLS with a self-signed certificate that was automatically generated on the laptop during the ...
2
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2answers
256 views

Authenticating code securely and generating a certificate

I'm working on a product with strong security. Essentially there is an App, downloaded from the iTunes App Store. When the App starts up, it generates a strong RSA keypair and stores it in the ...
2
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1answer
399 views

How to identify RSASSA-PSS from rsaEncryption OID?

Following the RFC 8446 it states that: RSASSA-PSS RSAE algorithms: Indicates a signature algorithm using RSASSA-PSS [RFC8017] with mask generation function 1. The digest used in ...
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1answer
271 views

Find hash and signature algorithms used in an X.509 certificate signed with RSASSA-PSS

I'm trying to understand the new PSS scheme, but having trouble figuring out how to parse it properly. When receiving a certificate with OID of RSASSA-PSS, how can I know which hash and signing ...
2
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1answer
211 views

How to generate a certificate/PEM from specific plain text keys?

Is there a way to generate a certificate with a pre-stablished public/private plaint text keys? Explaning: I generated some keys on a web site for development propurses, but now one of the parties ...
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2answers
104 views

Transferable ownership certificate

Is there a crytpographic way to assert ownership of an asset (let's say a piece of stone)? As an example, a number (public key) could be engraved in the stone, and the owner could keep a private key (...
2
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1answer
789 views

What is the maximum length of a X.509 OID?

I'm working on a feature for a project to determine if a given X.509 certificate is an EV Certificate, and if so, who is the authority behind that certificate. To do this, I grabbed the list of EV ...
2
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1answer
107 views

Any case that can require to encrypt a certificate revocation list before distribution

As far as we know certificate revocation lists (CRLs) include public information so they do not have to be encrypted before distribution. Is there a case that can require to encrypt it before ...
2
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1answer
155 views

Would SHA-1 be safe for certificates with short validity?

There are articles floating around the topic of SHA-1 deprecation. The gist of it is that in (mostly) developing countries, people are still using mobile/computing devices that are 5 years old (or ...
2
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1answer
186 views

Certificate for the public key

I am new to Network Security and learning about various security features like Diffie-Helmann and others. I understand that the Public key send by the server to the client needs to certified that it ...
2
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1answer
792 views

How can Bob validate Alice’s certificate?

Suppose that Alice has a certificate CA1 << Alice >> issued by the certification authority CA1, and Bob has a ...
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2answers
105 views

What data Certificate Authority encrypt for CSR?

I have been searching for a detailed explanation but can’t seem to find a low level one. 1) When CA sign the data with its private key, the encrypted data is APPENED to the csr or the whole cert ...
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3answers
4k views

Is there a complete list of Signature Algorithm names?

I need to analyze the output of rbsec's sslscan which reports a server's SSL/TLS configuration as reported by OpenSSL. I'm interested in the Certificate's Signature Algorithm in particular, and I was ...
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1answer
355 views

Can (EC)DH keys be used as the signed content in X.509 certificates?

From Wikipedia's article on ECDH: The public keys are either static (and trusted, say via a certificate)… Also see this question on this very site. These indicate to me that a certificate (maybe ...
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1answer
233 views

CRL number generation sequence: can I use a time stamp?

RFC 5280 states that the CRL number should monotonically increase. I have seen this common practice of incrementing the CRL number by 1, every time a new CRL is generated. But can I use a Unix (epoch ...
2
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1answer
549 views

Reusing PGP key when generating SSL Certificate Authority?

Does it make sense to reuse some of the keys from my PGP (gnupg, gpg) keyblock when generating my own SSL Certificate Authority (a toy one for myself and a few web services of mine)? In an ideal ...
2
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1answer
520 views

Digital Certificate Chain Verification

Does a certificate contain the complete chain of all certificates up to the trusted root certificate, or does the program that verifies certificates have to fetch each parent certificate individually ...
2
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1answer
174 views

Revoke a GPG key using previously generated revoke certificate after renewd (change expiration date)

I have few sub-questions Do secret keys get expired, or just the public key gets expired? Do I have to back up the master sec key each time I renew it? For an ...
2
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1answer
55 views

Secure scheme to share symmetric key using asymmetric keys and certificates with N parties

I need to distribute symmetric AES key into number of end points which will use it to decrypt data. The AES key will be the same on all end points, it is not possible to generate unique on every end ...
2
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1answer
123 views

X.509 strong authentication protocols

Is there also a protocol definition in X.509? In "Handbook of Applied Cryptography" by A. Menezes there is a reference to X.509 strong authentication protocol, nevertheless, I could not find the ...
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1answer
385 views

X509 CertificatePolicies, IssuerAlternativeNames, BasicConstraints extensions. What is done when Issuer signs?

I have got one theoretical question related to extensions of X509 Certificate. More precisely I have question about what is happening when issuer signs subject's certificate with has several ...
2
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1answer
458 views

Why does Apple create a certificate for my push notification key [closed]

Brief rundown of how Apple Push Notifications (APN) work: Generate a keypair, generate a CSR for it Upload the latter to your Apple Developer account and associate it with your mobile app In the ...
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1answer
164 views

How to pass an arbitrary signature to a certificate

I am trying to sign certificate (X509) using secret sharing. That is shareholders combine their signatures to produce the final signature which will be in this case the signed certificate. However ...
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1answer
2k views

Verification of identity by certification authority

I have question about how a user's identity is verified by a Certification Authority. As I understand it, the process works as follows: User generates his private key and (with the help of private ...
2
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1answer
655 views

Generate an insecure public / private key pair

I am looking for a way to generate an "insecure" public key pair. and by insecure I actually mean a pair that is breakable using brute-force (or other encryption) methods. As far as I know PGP ...
2
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0answers
54 views

What security is provided by a certificate? [closed]

I've been working on the topic of certificates for a little while, and here is what I understand: A certificate is basically a public key + some data about the owner of the certificate + a signature ...
2
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1answer
71 views

How does a receiver treat X.509 self-certificate with unknown the Signature Algorithm ID?

As I know X.509 self-certificate is a mechanism that the host generates public and private keys, the public key will insert to a certification and the private key will be used to sign the ...
2
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0answers
62 views

Compromised Issuing CA [closed]

I'm configuring a PKI infrastructure with an offline root CA and several issuing CAs. Among other topics, I'm struggling to decide how the revokation of an Issuing CA certificate works. My Root CA ...
2
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1answer
128 views

x509 CA trust question

I'm trying to understand the logic of CAs, trust and client certificates. I have a general understanding but am having a tough time bridging some gaps. In a hypothetical situation a software system ...
2
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0answers
575 views

Creating colliding x509 certificates: Crafting RSA moduli step

I am trying to generate 2 x509 certificates with the same signature but different values in the common name field, based on md5 collisions, as it was specified in this paper (page 7). Now I have ...
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2answers
3k views

Is Common Name encoded in the certificate?

When I make a certificate like so cd /etc/openvpn/easy-rsa/2.0/ source ./vars . /etc/openvpn/easy-rsa/2.0/build-key client1 Then ...
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1answer
5k views

Trying to understand the use of ECC in TLS certificates

I was looking the certificate of this website: https://www.cloudflare.com that has an ECC based certification. I'm just curious to know if is possible to understand which elliptic curve is used and ...
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1answer
689 views

What happens when a root CA loses its private key?

Certificate Authorities normally keep their private keys inside dedicated Hardware Security Modules (HSMs). What happens when such a device is lost (fire, electronic fault, stolen, etc)? How would ...
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3answers
164 views

Digital Certificates genereted from Hardware Security Module

Software library without hardware based source of entropy will provide enough security to generate digital certificates. However Hardware security Modules provide hardware based source of entropy and ...
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3answers
740 views

How does the certificate trust model work in detail?

How does the whole achitecture between the certificate authority (e.g VeriSign) and its clients (e.g foo.com) work. How does my browser know that foo.com hasn't created its own certificate, wrote "...
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1answer
128 views

How are all necessary parameters shared between signer and verifier in the ED25519 signature scheme?

I want to use the ED25519 signature scheme in my application which requires frequent sharing of secret data between two entities in the public domain. I know that the Schnorr signature scheme has a ...
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2answers
639 views

Why is the signature field in X.509 a BIT STRING, despite there being ASN.1 (DER) data inside?

As can be seen from the following ASN.1 definition of an X.509 certificate, the Signature field is a BIT STRING. ...
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1answer
122 views

What should I think about these unique certificate serial numbers [closed]

I was looking at the serial numbers of the certificates for www.google.com and wordpress.com. Wordpress was listed by openssl as: 04:0B:D4:F8:25:88:C5 This serial is listed as the serial for both ...
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1answer
119 views

How android apk file signing works?

There are a number of pages on web to tell how to sign apk file for Android. But none I've found telling how it works under-the-...
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1answer
44 views

How are certificate status obtained on browsers?

There are two ways of checking the status of a digital certificate:- Offline Authentication (CRL) Online Authentication (OCSP, SCVP) Several browsers (like Mozilla Firefox) have given up the use of ...