Invalid self signed SSL cert - "Subject Alternative Name Missing"

Recently, Chrome has stopped working with my self signed SSL certs, and thinks they're insecure. When I look at the cert in the DevTools | Security tab, I can see that it says

> Subject Alternative Name Missing The certificate for this site does > not contain a Subject Alternative Name extension containing a domain > name or IP address. > > Certificate Error There are issues with the site's certificate chain > (net::ERR_CERT_COMMON_NAME_INVALID).

How can I fix this?

To fix this, you need to supply an extra parameter to openssl when you're creating the cert, basically

-sha256 -extfile v3.ext

where v3.ext is a file like so, with %%DOMAIN%% replaced with the same name you use as your Common Name. More info here and over here. Note that typically you'd set the Common Name and %%DOMAIN%% to the domain you're trying to generate a cert for. So if it was www.mysupersite.com, then you'd use that for both.

v3.ext

authorityKeyIdentifier=keyid,issuer
basicConstraints=CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names

[alt_names]
DNS.1 = %%DOMAIN%%

Note: Scripts that address this issue, and create fully trusted ssl certs for use in Chrome, Safari and from Java clients can be found here

Another note: If all you're trying to do is stop chrome from throwing errors when viewing a self signed certificate, you can can tell Chrome to ignore all SSL errors for ALL sites by starting it with a special command line option, as detailed here on SuperUser

Following solution worked for me on chrome 65 (ref) -

Create an OpenSSL config file (example: req.cnf)

[req]
distinguished_name = req_distinguished_name
x509_extensions = v3_req
prompt = no
[req_distinguished_name]
C = US
ST = VA
L = SomeCity
O = MyCompany
OU = MyDivision
CN = www.company.com
[v3_req]
keyUsage = critical, digitalSignature, keyAgreement
extendedKeyUsage = serverAuth
subjectAltName = @alt_names
[alt_names]
DNS.1 = www.company.com
DNS.2 = company.com
DNS.3 = company.net

Create the certificate referencing this config file

openssl req -x509 -nodes -days 730 -newkey rsa:2048 \
 -keyout cert.key -out cert.pem -config req.cnf -sha256

The Issue

As others have mentioned, the NET::ERR_CERT_COMMON_NAME_INVALID error is occurring because the generated certificate does not include the SAN (subjectAltName) field.

RFC2818 has deprecated falling back to the commonName field since May of 2000. The use of the subjectAltName field has been enforced in Chrome since version 58 (see Chrome 58 deprecations).

OpenSSL accepts x509v3 configuration files to add extended configurations to certificates (see the subjectAltName field for configuration options).

---

Bash Script

I created a self-signed-tls bash script with straightforward options to make it easy to generate certificate authorities and sign x509 certificates with OpenSSL (valid in Chrome using the subjectAltName field).

The script will guide you through a series of questions to include the necessary information (including the subjectAltName field). You can reference the README.md for more details and options for automation.

Be sure to restart chrome after installing new certificates.

chrome://restart

---

Other Resources

• The Docker documentation has a great straightforward example for creating a self-signed certificate authority and signing certificates with OpenSSL.
• cfssl is also a very robust tool that is widely used and worth checking out.
• mkcert is a tool written in GoLang. It seems simple to use and great for local development.

I simply use the -subj parameter adding the machines ip address. So solved with one command only.

sudo openssl req -x509 -nodes -days 3650 -newkey rsa:2048 -sha256 -subj '/CN=my-domain.com/subjectAltName=DNS.1=192.168.0.222/' -keyout my-domain.key -out my-domain.crt

You can add others attributes like C, ST, L, O, OU, emailAddress to generate certs without being prompted.

I had so many issues getting self-signed certificates working on macos/Chrome. Finally I found Mkcert, "A simple zero-config tool to make locally trusted development certificates with any names you'd like." https://github.com/FiloSottile/mkcert

• Make a copy of your OpenSSL config in your home directory:

    cp /System/Library/OpenSSL/openssl.cnf ~/openssl-temp.cnf
  

  or on Linux:

    cp /etc/ssl/openssl.cnf ~/openssl-temp.cnf
  

• Add Subject Alternative Name to openssl-temp.cnf, under [v3_ca]:

    [ v3_ca ]
    subjectAltName = DNS:localhost
  

  Replace localhost by the domain for which you want to generate that certificate.

• Generate certificate:

    sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
        -config ~/openssl-temp.cnf
        -keyout /path/to/your.key -out /path/to/your.crt
  

You can then delete openssl-temp.cnf

Here is a very simple way to create an IP certificate that Chrome will trust.

The ssl.conf file...

[ req ]
default_bits       = 4096
distinguished_name = req_distinguished_name
req_extensions     = req_ext
prompt             = no

[ req_distinguished_name ]
commonName                  = 192.168.1.10

[ req_ext ]
subjectAltName = IP:192.168.1.10

Where, of course 192.168.1.10 is the local network IP we want Chrome to trust.

Create the certificate:

openssl genrsa -out key1.pem
openssl req -new -key key1.pem -out csr1.pem -config ssl.conf
openssl x509 -req -days 9999 -in csr1.pem -signkey key1.pem -out cert1.pem -extensions req_ext -extfile ssl.conf
rm csr1.pem

On Windows import the certificate into the Trusted Root Certificate Store on all client machines. On Android Phone or Tablet download the certificate to install it. Now Chrome will trust the certificate on windows and Android.

On windows dev box the best place to get openssl.exe is from "c:\Program Files\Git\usr\bin\openssl.exe"

I was able to get rid of (net::ERR_CERT_AUTHORITY_INVALID) by changing the DNS.1 value of v3.ext file

[alt_names] DNS.1 = domainname.com

Change domainname.com with your own domain.

on MAC starting from chrome Version 67.0.3396.99 my self-signed certificate stopped to work.

regeneration with all what written here didn't work.

UPDATE

had a chance to confirm that my approach works today :). If it doesn't work for you make sure your are using this approach

v3.ext
authorityKeyIdentifier=keyid,issuer
basicConstraints=CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names
 
[alt_names]
DNS.1 = <specify-the-same-common-name-that-you-used-while-generating-csr-in-the-last-step>
$

copied from here https://ksearch.wordpress.com/2017/08/22/generate-and-import-a-self-signed-ssl-certificate-on-mac-osx-sierra/

END UPDATE

finally was able to see green Secure only when removed my cert from system, and added it to local keychain. (if there is one - drop it first). Not sure if it maters but in my case I downloaded certificate via chrome, and verified that create date is today - so it is the one I've just created.

hope it will be helpful for someone spend like a day on it.

never update chrome!

Updated June 2021 - Windows 10 - Chrome v91 answer is here

If you want to run your server localhost, you need to setup CN = localhost and DNS.1 = localhost.

[req]
default_bits = 2048
default_md = sha256
distinguished_name = req_distinguished_name
prompt = no
prompt = no
x509_extensions = v3_req

[req_distinguished_name]
C = BR
CN = localhost
emailAddress[email protected]
L = Sao Paulo
O = example.com
OU = example.com
ST = Sao Paulo

[v3_req]
authorityKeyIdentifier = keyid, issuer
basicConstraints = CA:FALSE
extendedKeyUsage = serverAuth
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names

[alt_names]
DNS.1 = localhost