How can I create a self-signed cert for localhost?

Question

I've gone through the steps detailed in How do you use https / SSL on localhost? but this sets up a self-signed cert for my machine name, and when browsing it via https://localhost I receive the IE warning.

Is there a way to create a self-signed cert for "localhost" to avoid this warning?

Answer 1

Since this question is tagged with IIS and I can't find a good answer on how to get a trusted certificate I will give my 2 cents about it:

First use the command from @AuriRahimzadeh in PowerShell as administrator:

New-SelfSignedCertificate -DnsName "localhost" -CertStoreLocation "cert:\LocalMachine\My" -NotAfter (Get-Date).AddYears(100)

Added Valid to 100 years so that the cert for localhost hopefully does not expire. You can use -NotAfter (Get-Date).AddMonths(24) for 24 months if you want that instead or any other value.

This is good but the certificate is not trusted and will result in the following error. It is because it is not installed in Trusted Root Certification Authorities.

Solve this by starting mmc.exe.

Then go to:

File -> Add or Remove Snap-ins -> Certificates -> Add -> Computer account -> Local computer. Click Finish.

Expand the Personal folder and you will see your localhost certificate:

Copy the certificate into Trusted Root Certification Authorities - Certificates folder.

The final step is to open Internet Information Services (IIS) Manager or simply inetmgr.exe. From there go to your site, select Bindings... and Add... or Edit.... Set https and select your certificate from the drop down.

Your certificate is now trusted:

Answer 2

Although this post is post is tagged for Windows, it is relevant question on OS X that I have not seen answers for elsewhere. Here are steps to create a self-signed cert for localhost on OS X:

# Use 'localhost' for the 'Common name'
openssl req -x509 -sha256 -nodes -newkey rsa:2048 -days 365 -keyout localhost.key -out localhost.crt

# Add the cert to your keychain
open localhost.crt

In Keychain Access, double-click on this new localhost cert. Expand the arrow next to "Trust" and choose to "Always trust". Chrome and Safari should now trust this cert. For example, if you want to use this cert with node.js:

var options = {
    key: fs.readFileSync('/path/to/localhost.key').toString(),
    cert: fs.readFileSync('/path/to/localhost.crt').toString(),
    ciphers: 'ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES256-SHA384',
    honorCipherOrder: true,
    secureProtocol: 'TLSv1_2_method'
};

var server = require('https').createServer(options, app);

Answer 3

You can use PowerShell to generate a self-signed certificate with the new-selfsignedcertificate cmdlet:

New-SelfSignedCertificate -DnsName "localhost" -CertStoreLocation "cert:\LocalMachine\My"

Note: makecert.exe is deprecated.

Cmdlet Reference: https://learn.microsoft.com/en-us/powershell/module/pki/new-selfsignedcertificate?view=windowsserver2022-ps

Answer 4

After spending a good amount of time on this issue I found whenever I followed suggestions of using IIS to make a self signed certificate, I found that the Issued To and Issued by was not correct. SelfSSL.exe was the key to solving this problem. The following website not only provided a step by step approach to making self signed certificates, but also solved the Issued To and Issued by problem. Here is the best solution I found for making self signed certificates. If you'd prefer to see the same tutorial in video form click here.

A sample use of SelfSSL would look something like the following:

SelfSSL /N:CN=YourWebsite.com /V:1000 /S:2

SelfSSL /? will provide a list of parameters with explanation.

Answer 5

If you are trying to create a self signed certificate that lets you go http://localhost/mysite Then here is a way to create it

makecert -r -n "CN=localhost" -b 01/01/2000 -e 01/01/2099 -eku 1.3.6.1.5.5.7.3.1 -sv localhost.pvk localhost.cer
cert2spc localhost.cer localhost.spc
pvk2pfx -pvk localhost.pvk -spc localhost.spc -pfx localhost.pfx

From http://social.msdn.microsoft.com/Forums/en-US/wcf/thread/32bc5a61-1f7b-4545-a514-a11652f11200

Answer 6

I would recomment Pluralsight's tool for creating self-signed-certs: http://blog.pluralsight.com/selfcert-create-a-self-signed-certificate-interactively-gui-or-programmatically-in-net

Make your cert as a .pfx and import it into IIS. And add it as a trusted root cert authority.

Answer 7

Fastest Way to generate localhost certificate.

openssl req -x509 -out localhost.crt -keyout localhost.key \
  -newkey rsa:2048 -nodes -sha256 \
  -subj '/CN=localhost' -extensions EXT -config <( \
   printf "[dn]\nCN=localhost\n[req]\ndistinguished_name = dn\n[EXT]\nsubjectAltName=DNS:localhost\nkeyUsage=digitalSignature\nextendedKeyUsage=serverAuth")

Answer 8

Yes and no. Self signed certificates result in that warning message because the certificate was not signed by a trusted Certificate Authority. There are a few options that you can consider to remove this warning on your local machine. See the highest ranked answers to this question for details:

What do I need to do to get Internet Explorer 8 to accept a self signed certificate?

Hope this helps!

---

EDIT:

Sorry, I wasn't initially aware that you were constrained to localhost. You can attempt to follow the directions on the the link below to "Generate a Self Signed Certificate with the Correct Common Name."

http://www.sslshopper.com/article-how-to-create-a-self-signed-certificate-in-iis-7.html

Answer 9

In a LAN (Local Area Network) we have a server computer, here named xhost running Windows 10, IIS is activated as WebServer. We must access this computer via Browser like Google Chrome not only from localhost through https://localhost/ from server itsself, but also from other hosts in the LAN with URL https://xhost/ :

https://localhost/
https://xhost/
https://xhost.local/
...

With this manner of accessing, we have not a fully-qualified domain name, but only local computer name xhost here.

Or from WAN:

https://dev.example.org/
...

You shall replace xhost by your real local computer name.

None of above solutions may satisfy us. After days of try, we have adopted the solution openssl.exe. We use 2 certificates - a CA (self certified Authority certificate) RootCA.crt and xhost.crt certified by the former. We use PowerShell.

1. Create and change to a safe directory:

cd C:\users\so\crt

2. Generate RootCA.pem, RootCA.key & RootCA.crt as self-certified Certification Authority:

openssl req -x509 -nodes -new -sha256 -days 10240 -newkey rsa:2048 -keyout RootCA.key -out RootCA.pem -subj "/C=ZA/CN=RootCA-CA"
openssl x509 -outform pem -in RootCA.pem -out RootCA.crt

3. make request for certification: xhost.key, xhost.csr:

C: Country
ST: State
L: locality (city)
O: Organization Name
Organization Unit
CN: Common Name

    

openssl req -new -nodes -newkey rsa:2048 -keyout xhost.key -out xhost.csr -subj "/C=ZA/ST=FREE STATE/L=Golden Gate Highlands National Park/O=WWF4ME/OU=xhost.home/CN=xhost.local"

4. get xhost.crt certified by RootCA.pem:

openssl x509 -req -sha256 -days 1024 -in xhost.csr -CA RootCA.pem -CAkey RootCA.key -CAcreateserial -extfile domains.ext -out xhost.crt

with extfile domains.ext file defining many secured ways of accessing the server website:

authorityKeyIdentifier=keyid,issuer
basicConstraints=CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names
[alt_names]
DNS.1 = localhost
DNS.2 = xhost
DNS.3 = xhost.local
DNS.4 = dev.example.org
DNS.5 = 192.168.1.2

5. Make xhost.pfx PKCS #12,

combinig both private xhost.key and certificate xhost.crt, permitting to import into iis. This step asks for password, please let it empty by pressing [RETURN] key (without password):

openssl pkcs12 -export -out xhost.pfx -inkey xhost.key -in xhost.crt

6. import xhost.pfx in iis10

installed in xhost computer (here localhost). and Restart IIS service.

IIS10 Gestionnaire des services Internet (IIS) (%windir%\system32\inetsrv\InetMgr.exe)

7. Bind ssl with xhost.local certificate on port 443.

Restart IIS Service.

8. Import RootCA.crt into Trusted Root Certification Authorities

via Google Chrome in any computer that will access the website https://xhost/.

\Google Chrome/…/Settings /[Advanced]/Privacy and Security/Security/Manage certificates

Import RootCA.crt

The browser will show this valid certificate tree:

RootCA-CA
  |_____ xhost.local

No Certificate Error will appear through LAN, even through WAN by https://dev.example.org.

Here is the whole Powershell Script socrt.ps1 file to generate all required certificate files from the naught:

#
# Generate:
#   RootCA.pem, RootCA.key RootCA.crt
#
#   xhost.key xhost.csr xhost.crt
#   xhost.pfx
#
# created  15-EEC-2020
# modified 15-DEC-2020
#
#
# change to a safe directory:
#

cd C:\users\so\crt

#
# Generate RootCA.pem, RootCA.key & RootCA.crt as Certification Authority:
#
openssl req -x509 -nodes -new -sha256 -days 10240 -newkey rsa:2048 -keyout RootCA.key -out RootCA.pem -subj "/C=ZA/CN=RootCA-CA"
openssl x509 -outform pem -in RootCA.pem -out RootCA.crt

#
# get RootCA.pfx: permitting to import into iis10: not required.
#
#openssl pkcs12 -export -out RootCA.pfx -inkey RootCA.key -in RootCA.crt

#
# get xhost.key xhost.csr:
#   C: Country
#   ST: State
#   L: locality (city)
#   O: Organization Name
#   OU: Organization Unit
#   CN: Common Name
#
openssl req -new -nodes -newkey rsa:2048 -keyout xhost.key -out xhost.csr -subj "/C=ZA/ST=FREE STATE/L=Golden Gate Highlands National Park/O=WWF4ME/OU=xhost.home/CN=xhost.local"

#
# get xhost.crt certified by RootCA.pem:
# to show content:
#   openssl x509 -in xhost.crt -noout -text
#
openssl x509 -req -sha256 -days 1024 -in xhost.csr -CA RootCA.pem -CAkey RootCA.key -CAcreateserial -extfile domains.ext -out xhost.crt

#
# get xhost.pfx, permitting to import into iis:
#
openssl pkcs12 -export -out xhost.pfx -inkey xhost.key -in xhost.crt

#
# import xhost.pfx in iis10 installed in xhost computer (here localhost).
#

To install openSSL for Windows, please visit https://slproweb.com/products/Win32OpenSSL.html

Answer 10

you could try mkcert.

macos: brew install mkcert

Answer 11

If you are using Visual Studio, there is an easy way to setup and enable SSL using IIS Express explained here

Answer 12

Here's what I did to get a valid certificate for localhost on Windows:

1. Download mkcert executable (https://github.com/FiloSottile/mkcert/releases) and rename it to mkcert.exe
2. Run "mkcert -install"
3. Open Windows certificate manager (certmgr.msc)
4. Right click on "Trusted Root Certification Authorities" -> Import
5. Import Root cert (rootCA.pem) from C:\Users[username]\AppData\Local\mkcert\
6. Create a *.p12 certificate for specified domain(s): "mkcert -pkcs12 [name1] [name2]"
7. Rename *.p12 certificate into *.pfx
8. In IIS -> Server Certificates -> Import (pfx) in "Personal" group [default password: "changeit"]
9. Assign certificate to Default Web Site (binding -> https (443) -> modify -> SSL certificate)

Answer 13

Solution for Windows 10

None of the above worked for me but this one:

1. Follow these steps

$cert = New-SelfSignedCertificate -Subject local.YourDomain -DnsName local.yourdomain.co.uk

then

Format-List -Property *

or steps under Creating A Certificate With a Single Subject here: https://adamtheautomator.com/new-selfsignedcertificate/

You can also try SAN (Creating A Subject Alternative Name (SAN) Certificate).

2. Open mmc

Open Windows search and type mmc

then follow these steps:

Open File > Add/Remove Snap-in, select Certificates and click Add. Select Computer account, click Next and then Finish.

3. Copy certificate from Personal to Trusted

Expand Personal under Certificates in mmc

Copy your new certificate from Personal to Trusted Root Certification Authorities

4. Select the new certificate for your domain binding in IIS

5. Restart the domain/ site