Questions tagged [certificates]

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

Filter by
Sorted by
Tagged with
3
votes
2answers
822 views

X.509 CSR: Why does CA remove signature?

I just read this article on Wikipedia: Certificate Signing Request I'm not a PKI or Crypto expert. As I understand, a CSR (certification request) is always signed by the PKCS#10-Request creator. ...
3
votes
1answer
105 views

How can I validate a given Server-Certificate behind a HTTPS-connection?

I know more or less about how TLS works in principle. But how can I be sure, that the certificate behind a server's web site (e.g. tele-banking from my bank) has been issued to my bank and not to ...
3
votes
3answers
446 views

Does the Shappening mean HTTPS can be broken?

For years we've been warned that SHA-1 is weaker than originally thought and should not be used. This reached its peak with the Shappening and experts from Schneier on down have been warning that we ...
3
votes
2answers
2k views

TLS Handshake : Server authentication or only Server ‘s Certificate authentication?

I have some difficulty understanding the way in which the Server is really authenticated by Client in TLS handshake (in case of using RSA key exchange). When Client receives Server ‘s Certificate and ...
3
votes
1answer
71 views

Allowed key types in an SSL certificate

What are the valid key types which can get signed (or generated and signed) by a CA to constitute an SSL certificate? For the keys used in TLS, the key types I have seen are RSA and EC. Anything else? ...
3
votes
1answer
52 views

Enforce weak RSA in TLS

I'm going to give a small talk on the mathematical background of RSA. My audience will consist mostly of software engineers and to make the mathematical stuff tangible, I wanted to demonstrate how to ...
3
votes
2answers
163 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 (...
3
votes
4answers
142 views

Possible to use an accumulator to “license” or restrict the qty of certificates being used?

Suppose in a future version of x509 PKI, it is possible to limit the quantity of certificates being used, what would that look like? Here is a concept that won't work in the real world, but ...
3
votes
1answer
144 views

Manually creating a GPG Public Key

I want to manually create a GPG public key that can be imported into GPG, i.e. I want to create a file with a Public-Key Packet, a User ID Packet and a Signature Packet (for an example see here). I ...
3
votes
1answer
131 views

What is the RFC order of peer certificate verification, trust chain or expiry first?

If a certificate received from a peer: Is expired, has a valid signature, but from an untrusted root CA What error should be thrown? Untrusted certificate or expired certificate? I can't seem to ...
3
votes
1answer
5k views

Extra attributes in a certificate signing request

When creating a certificate signing request, there is a part where openssl says "Please enter the following extra attributes to be sent with your certificate request". One of these is a challenge ...
3
votes
1answer
714 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 ...
3
votes
1answer
146 views

X509 certificates: Two Algorithm Identifiers?

I'm wondering why there are two Algorithm Identifiers in a X509 certificate. One is in the "to be signed" part and the other one is at the end right before the actual signature. Are they used for the ...
3
votes
1answer
115 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, ...
3
votes
2answers
413 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 ...
3
votes
0answers
643 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 ...
3
votes
1answer
48 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 ...
2
votes
3answers
5k 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
votes
2answers
508 views

openSSL created CSR signature size of 73 bytes but should't it be 70 bytes

after creating CSR using openSSL with secp256r1 curve inspecting the file using openssl asn1parse -i -in ecTest.csr the size of ...
2
votes
2answers
1k 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
votes
2answers
4k 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 ...
2
votes
1answer
198 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 ...
2
votes
1answer
1k 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 ...
2
votes
1answer
105 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.
2
votes
1answer
86 views

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

I have the following X509 certificate: ...
2
votes
2answers
2k 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. ...
2
votes
1answer
2k 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-...
2
votes
1answer
1k 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 ...
2
votes
3answers
95 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
votes
2answers
263 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
votes
1answer
1k 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 ...
2
votes
1answer
866 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
votes
1answer
1k 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 ...
2
votes
1answer
1k views

RSA certificate needed in CVC format

I had a client requirement asking me to provide an existing base64 encoded certificate in a CVC format. Could someone point me in the right direction here to understand what this format is? How can I ...
2
votes
1answer
162 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
votes
1answer
171 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
votes
1answer
252 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
votes
1answer
1k 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 ...
2
votes
2answers
223 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 ...
2
votes
1answer
267 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
votes
1answer
615 views

Reusing PGP key when generating SSL Certificate Authority?

Does it make sense to reuse some of the keys from my PGP (GnuPG, GPG) key block when generating my own SSL Certificate Authority (a toy one for myself and a few web services of mine)? In an ideal ...
2
votes
1answer
528 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
votes
3answers
1k views

What exactly is the contents of the LDAP userSMIMECertificate attribute?

I'm trying to setup an LDAP with user certificates. I have already learned that certificates can be stored in either the userCertificate attribute in DER format, or ...
2
votes
1answer
120 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
votes
1answer
224 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 ...
2
votes
1answer
611 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
votes
1answer
519 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 ...
2
votes
1answer
172 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 ...
2
votes
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
votes
1answer
739 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 ...