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98 votes
Accepted

Why is there no certificate error while visiting google.net although it presents a certificate issued to google.com?

SNI hole You've fallen into a "SNI hole". Google will present a different certificate if there is no "Server Name Indication" given in the client's TLS handshake part. OpenSSL will not set this ...
StackzOfZtuff's user avatar
50 votes
Accepted

Are SSL certs auto-revoked if their Not-Valid-After date is reached without renewing?

No. Revocation is an active event, not something that passively or automatically happens. Expiration is passive, though. An expired cert is no longer valid, so there's no need to stick it in a CRL or ...
CBHacking's user avatar
  • 48.5k
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
  • 6,131
40 votes
Accepted

Missing X509 extensions with an openssl-generated certificate

According to the bugs section of the x509 command documentation, Extensions in certificates are not transferred to certificate requests and vice versa. To work around this, I manually added the ...
rwm's user avatar
  • 516
40 votes
Accepted

The difference between Subject Key Identifier and sha1Fingerprint in X509 Certificates

The subject key identifier (SKID) is an x509 extension and thus actually part of the certificate. The fingerprint instead is not part of the certificate but instead computed from the certificate. A ...
Steffen Ullrich's user avatar
39 votes
Accepted

Can a SSL certificate have longer validity period than its parent in X.509 chain?

This is an historically disputed point. In the validation algorithm from RFC 5280 (that supersedes RFC 2459, by the way), there is no requirement of validity range nesting. However, some historical ...
Tom Leek's user avatar
  • 173k
39 votes

Why don't folks seem to use ECC for TLS root certificate signature?

There's a slide deck on NIST by Rick Andrews, Senior Technical Director and Distinguished Engineer of Symantec, titled Symantec’s View of the Current State of ECDSA on the Web (published 2015) ...
phbits's user avatar
  • 1,052
35 votes
Accepted

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

CA A revokes CA B, does certificate C become invalid? Yes, revocation cascades down to the tree. If CA certificate is revoked, all certificates below (regardless of how many levels are below CA) are ...
Crypt32's user avatar
  • 6,381
30 votes

Could governments and banks become CAs?

I know of at least one government that has a root CA: The state of the Netherlands. As far as I know they don't use it to identify people when they come pick up their driver license. I think ...
Sjoerd's user avatar
  • 30.7k
30 votes
Accepted

Is it possible to update the contact info (FN/LN, OU, Organization,..) of a certificate?

No, if you changed those informations on the certificate, the fingerprint changed, and the signature is invalid. You will need to issue a new certificate.
ThoriumBR's user avatar
  • 54.3k
27 votes

Why don't folks seem to use ECC for TLS root certificate signature?

TL;DR: There is nothing technically wrong with ECC; in fact it has better bandwidth and server CPU load than RSA (but higher CPU load on browsers, thanks @CodesInChaos), but for historical reasons it ...
Mike Ounsworth's user avatar
21 votes

Are SSL certs auto-revoked if their Not-Valid-After date is reached without renewing?

You MUST check the expiration date first. You can do that locally, without creating a connection to the OCSP server and spending network resources at both your end and OCSP server's end. (And yes, I ...
fraxinus's user avatar
  • 3,568
20 votes

Could governments and banks become CAs?

To complement Sjoerd's answer: some countries even give every single citizen and resident their own certificates, stored inside an ICC that is also the primary identity document. For illustration, ...
Constantino Tsarouhas's user avatar
17 votes

Determine if private key belongs to certificate?

The accepted answer is correct, but it only works for RSA keys. At least since openssl 1.1.1 it is possible to test validity of all types of private keys and here's a one-liner that works for all ...
Manish's user avatar
  • 199
17 votes

Can a SSL certificate have longer validity period than its parent in X.509 chain?

Hmm, I agree that I would have expected to find this info in RFC 5280 4.1.2.5. Validity. (By the way, RFC 5280 obsoletes RFC 3280, which obsoletes RFC 2459, so you really shouldn't be looking at 2459 ...
Mike Ounsworth's user avatar
17 votes

Is it possible to update the contact info (FN/LN, OU, Organization,..) of a certificate?

I like to compare certificates to driver's licenses. Can you take a sharpie and change the First Name, Last Name, Address on your driver's license? No, you need to contact the government and get a new ...
Mike Ounsworth's user avatar
16 votes

How long can X.509 certificate chains be?

Theoretically, X.509 chains are unlimited in length. The Basic Constraints extension can apply a per-chain limit; this is used mostly for CA that agree to issue a sub-CA certificate but want to ...
Thomas Pornin's user avatar
16 votes
Accepted

Generate Subject Key Identifier by hand using openssl command sequence

From http://certificateerror.blogspot.se/2011/02/how-to-validate-subject-key-identifier.html. Extract SKI from cert: #!/bin/bash ...
Konrad Eisele's user avatar
16 votes
Accepted

Why one should prefer EST protocol instead of SCEP?

What is SCEP? Simple Certificate Enrollment Protocol is a certificate enrollment protocol originally defined by Cisco in the 2011 IETF Internet-Draft draft-nourse-scep, and more recently in the 2018 ...
Mike Ounsworth's user avatar
15 votes
Accepted

Definitions for CRL Reasons

[Disclaimer: I work as a software developer on the software that powers one of the trusted public CAs, and many corporate internal PKIs] tl;dr: to my knowledge, there are no formal guidelines for ...
Mike Ounsworth's user avatar
15 votes
Accepted

Why don't folks seem to use ECC for TLS root certificate signature?

It's uncommon to see a signature by a root certificate using ECDSA, because most root certificates contain RSA public keys, not ECC public keys. Moreover, because root certificates must be installed ...
mti2935's user avatar
  • 23.5k
14 votes
Accepted

How long can X.509 certificate chains be?

There is no technical/specification limit imposed on the length of certificate chains. (However, there are X509v3 attributes which can impose policy-based limits on the length of a certificate chain ...
Castaglia's user avatar
  • 560
14 votes
Accepted

How TLS certificate chain is verified

(1) Does the verification of the chain end there or does it continue on until we get to D? it depends on a certificate chaining engine (CCE) implementation. Different platforms have different ...
Crypt32's user avatar
  • 6,381
13 votes
Accepted

One certificate for both client and server authentication

From a normative point of view, RFC5280 does not put any constraint on having both extended key usages set at the same certificate. From the security point of view, there is also no crypto/protocol ...
CristianTM's user avatar
  • 2,580
13 votes

Could governments and banks become CAs?

•Is there any reason (from a security standpoiny) that a government, bank, or credit card company should not be part of PKI? Mixing business and worldwide government interests isn't something most ...
Matthew1471's user avatar
  • 1,144
13 votes
Accepted

CRL over HTTPS: is it really a bad practice?

I generally agree with Steffen Ulrich, I just want to add few cents, since OP references my own answer which I consider proper and valid. However OSCP responses are also signed by a revocable entity ...
Crypt32's user avatar
  • 6,381
12 votes
Accepted

Subject Alternative Name in Certificate Signing Request apparently does not survive signing

The following command apparently resolves the issue: openssl x509 -req -days 365 -CA ca.crt -CAkey ca.key -CAcreateserial \ -extensions SAN \ -extfile <(cat /etc/ssl/openssl.cnf \ <(...
Drux's user avatar
  • 391
12 votes
Accepted

Key differences between X509 TLS Client certificate and server certificate

Structurally, client and server certs are the same. Both will need keyUsage: digitalSignature and will contain the same type of RSA or ECDSA key. They chain to an intermediate and root CA via Issuer ...
Mike Ounsworth's user avatar
11 votes
Accepted

Why don't banks sign their email using S/MIME?

It's usually a costs vs. benefits decision. Costs: Create your own CA infrastructure or buy a public certificate for each sender Teach employees how to use it Teach employees how not to use it, ...
Steffen Ullrich's user avatar
11 votes

Are X.509 nameConstraints on certificates supported on OS X?

Yes, OS X / macOS supports this since 10.13.3. According to the https://nameconstraints.bettertls.com archived tests, 10.13 failed some tests but 10.13.3 passes all in with both Safari and Chrome. ...
Gabriel's user avatar
  • 163

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