42 votes
Accepted

What's the point of certificates in SSL/TLS?

The signed CA response you envision is a certificate. Maybe not a classical X.509 certificate that we currently use, and maybe much more short-lived, but conceptually, it serves the exact same purpose ...
Ja1024's user avatar
  • 4,569
27 votes

Do subdomains of a TLD with mandatory HTTPS require a wildcard certificate?

Many new TLDs have mandatory HTTPS requirements. Is there a way to disable that for subdomains? No. Mandatory means that TLS is not only required for the "bare" domain but also for the ...
Steffen Ullrich's user avatar
17 votes

How does the SSL/TLS protocol determine if a certificate is expired or not?

how the SSL/TLS protocol does it The SSL/TLS protocol does not define how certificates are validated. You need to look instead RFC 5280, which is about certificates in general. SSL/TLS just makes use ...
Steffen Ullrich's user avatar
15 votes

Do subdomains of a TLD with mandatory HTTPS require a wildcard certificate?

A single certificate can cover a large number of domains through the Subject Alternative Name (SAN) extension. The maximum number may vary between different CAs, but Let's Encrypt supports up to 100 ...
Ja1024's user avatar
  • 4,569
12 votes
Accepted

.exe with Digital Signature, showing SHA1 but the Certificate is SHA384, is it secure?

The other answers correctly point out that SHA1 is not a watertight hashing algorithm: SHA1 is vulnerable to collision attacks. However, there are no known vulnerabilities to SHA1's preimage ...
Alex W's user avatar
  • 235
11 votes

.exe with Digital Signature, showing SHA1 but the Certificate is SHA384, is it secure?

It is not ok to use SHA1 authenticode signatures in 2023, they are not considered secure. Because of quite realistic SHA1 collision, the code might be tampered in the way that it will produce same ...
Crypt32's user avatar
  • 6,281
10 votes
Accepted

What is the current (April 2023) browser support for Ed25519 certificate signatures?

You are correct, currently neither Chrome nor Firefox support the EdDSA signature scheme (i.e. neither Ed25519 nor Ed448). For Firefox, there is a Bugzilla ticket open regarding support for Ed25519 in ...
Nummer378's user avatar
  • 186
9 votes

What's the point of certificates in SSL/TLS?

Think of the certificate as an official signed statement confirming that the public key belongs to a particular host. The CRL/OCSP systems are there so that you can confirm that the official signed ...
ARGYROU MINAS's user avatar
5 votes

.exe with Digital Signature, showing SHA1 but the Certificate is SHA384, is it secure?

As for understanding the 'nested construction', it might help to understand the sequence of operations in this process: Phase to Phase created a key pair consisting of a private key and a public key. ...
mti2935's user avatar
  • 23.4k
5 votes
Accepted

Restrict VPN access to only authorised machines

Different VPN clients have different methods for accomplishing this. some issue device-bounded clients that are generated from a base server, so users only get one, and the client is machine-bound, ...
schroeder's user avatar
  • 129k
5 votes

Missing X509 extensions with an openssl-generated certificate

2023 edition of the answer to this question is to use -copy_extensions=copyall as the bug in openssl is fixed in v3 as one of the commenter has mentioned. Given the private key already exists, we can ...
Anton Golubev's user avatar
4 votes

Leaving SSH access to deployed on prem server -- why is this bad?

The question is less about SSH vs. HTTPS as the transport protection, but about what actually can be done with the access. SSH typically provides a powerful shell to run arbitrary commands, although ...
Steffen Ullrich's user avatar
4 votes

self signed certificate

If you have a company VPN, it's very likely that you will have a company CA. If this is true, you can create a Certificate Request, send to the team/group/person managing the company CA and have the ...
ThoriumBR's user avatar
  • 53.9k
3 votes
Accepted

Are certificates persistent outside of where it's created?

Cloudflare doesn't issue its own certificates. It's merely a reseller for certificate authorities (CAs) like DigiCert, Let's Encrypt or Google Trust Services. This means the certificates are perfectly ...
Ja1024's user avatar
  • 4,569
3 votes
Accepted

Does a certificate revocation list (CRL) keep it's entries at least as long as the certificate would have been valid?

Is every CRL issued by this CA guaranteed to include its revocation, as long as the original certificate would still be valid? Well, of course nothing is ever guaranteed, but that is at least ...
mkl's user avatar
  • 1,093
3 votes

is mTLS authentication alone considered secure for authentication

Yes, mutual TLS (mTLS) is sufficient for client authentication. With mutual TLS, the client knows it is actually talking to the server, and the server is actually talking to the client. Both parties ...
Sjoerd's user avatar
  • 30.4k
2 votes

Is NordVPN changing my security cerificates? Could this be a MiTM attack?

I came across the same issue yesterday on a computer I was supporting. Given that NordVPN is one of the biggest VPN providers I'd say this is probably not a MitM attack. That being said, there's a few ...
Fake user's user avatar
2 votes

Why cannot I see google's root certificate in certificate manager?

I don't know what browser or OS you're using, or what website you visited, but: GTS Root R1 has self-signed certificates, but it also has a certificate issued by GlobalSign's GlobalSign Root CA, an ...
Matt Nordhoff's user avatar
2 votes
Accepted

openssl ca -revoke causes `Can't open ./demoCA/cacert.pem`

Partial dupe How do I revoke the certificate and generate a CRL? and compare to Revoke a certificate without index.txt The openssl ca command does three related but different things to manage ...
dave_thompson_085's user avatar
2 votes
Accepted

Suitable method of encryption for user-hosted chat platforms

Suitable method of encryption for user-hosted chat platforms ... but it needs to be safe from a MITM attack because passwords are sent over the connection No method of encryption protects by its own ...
Steffen Ullrich's user avatar
2 votes
Accepted

How do TLS clients validate intermediate CA certificates?

Verifying the trust chain is an essential part of the certificate validation, the one which involves the intermediate certificates. It means to build the trust path from the peers leaf certificate to ...
Steffen Ullrich's user avatar
2 votes
Accepted

what is the difference between the root CA certificate and the intermediate CSR certificate

You need to read one step further in the tutorial. The CSR is the Certificate Signing Request, not a certificate. This CSR is then passed to the CA to produce a certificate signed by the CA. So we're ...
Ja1024's user avatar
  • 4,569
2 votes

what is the difference between the two openssl commands below

The difference is that the second command uses the entire CA “infrastructure” defined in the CA configuration and consisting of, for example, a certificate database, a counter for the serial numbers, ...
Ja1024's user avatar
  • 4,569
2 votes
Accepted

How to identify certificate package type?

The file is in PKCS #7 format. You can read it with openssl pkcs7 -in Cadeia_FIREFOX.der -inform der -print_certs -noout The file is a chain of certificates, not just a single CA certificate. To ...
Ja1024's user avatar
  • 4,569
2 votes

What's the point of certificates in SSL/TLS?

"A valid certificate cannot guarantee that I'm not being MITM'd right now, since the certificate may have been compromised" In practice, this is mostly a non issue, as for all practical ...
Bruno Rohée's user avatar
  • 5,507
2 votes

What's the point of certificates in SSL/TLS?

I think it's important to look at the historical context here, because successful protocols are generally built on what came before, not designed from scratch. Netscape first released SSL to the ...
IMSoP's user avatar
  • 3,860
2 votes
Accepted

Is Certificate Pinning safe and worthwhile for an API server that will only accept requests from an android application?

I don't understand that while Pinning itself might be obsolete ... It is not. The sources you cite are only about HPKP, which is a very specific type of pinning where the negative impact of doing it ...
Steffen Ullrich's user avatar
2 votes
Accepted

How to set/modify "positive trust attributes" in a certificate for openssl

In my question I stated that "there is no information about how to set" trust attributes. This is not correct as man openssl-x509 describes how to set these attributes: -addtrust arg ...
Cris's user avatar
  • 83
2 votes

Website returns different certificate on my home network to mobile hotspot

If this is only about a single site this might be a misconfiguration. A common problem is to have the right configuration with IPv4 but a wrong configuration with IPv6. Check SSLLabs. It might also be ...
Steffen Ullrich's user avatar
2 votes
Accepted

openssl: genrsa vs req -newkey private keys. What's the difference?

By default, the openssl genrsa in both OpenSSL 1.1.1f & 3.0.9 generates a 2048-bit RSA key, as well as the openssl req -newkey rsa. If you examine the resulting private keys with openssl rsa -text ...
Esa Jokinen's user avatar
  • 18.9k

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