Configure SSL/HTTPS on Tomcat with Self-Signed Certificate

16 11 2014

Regarding security, the https with SSL is a minimum requirement. Moreover it has relatively low cost in implementation. Thanks to it your transport layer will be encrypted, preventing sniffing and main in the middle attack. Thanks to it your server validity will be verified with a certificate (In this tutorial I will use self-signed certificate. If you need trusted certificate, follow the trust agency instructions).

1. Generate keystore with self-signed certificate in it

You can generate keystore with java’s keytool. Open the windows command line or shell and check if you have keytool command in your path. If command is not recognized, find keytool app in your %java_home%\bin directory.

Execute this command:

keytool -genkey -alias keyAlias -storetype PKCS12 -keyalg RSA -keysize 2048 -keystore myKeystore.p12 -validity 3650

The keytool will generate key (-genkey) with alias (-alias), PKCS12 storetype (-storetype), RSA algorthm 2048 bytes long stored under myKeystore.p12 file with validity equal to 3650 days (10 years).

Executing this command will ask you few identity questions:

Enter keystore password: keyPwd
Re-enter new password: keyPwd
What is your first and last name?
What is the name of your organizational unit?
  [Unknown]:  LooksOK!
What is the name of your organization?
  [Unknown]:  LooksOK!
What is the name of your City or Locality?
  [Unknown]:  Minsk Mazowiecki
What is the name of your State or Province?
  [Unknown]:  mazowieckie
What is the two-letter country code for this unit?
  [Unknown]:  PL
Is CN=, OU=LooksOK!, O=LooksOK!, L=Minsk Mazowiecki, ST=mazowieckie, C=PL correct?
  [no]:  yes

2. Check keystore contents – find your certificate in there

Issue list command to ensure that keystore contains certificate:

keytool -list -keystore keystore.p12 -storetype PKCS12

This is the output:

Keystore type: PKCS12
Keystore provider: SunJSSE

Your keystore contains 1 entry

keyalias, 2014-11-14, PrivateKeyEntry,
Certificate fingerprint (SHA1): 5A:3C:63:EC:CD:A9:AE:AA:D1:92:B3:3A:68:5A:95:C2:98:E3:69:01

So, the certificate is truly there!

3. Copy your keystore file to Tomcat dir

You can put your keystore file whenever you want, providing you will enter the path in tomcat config. I encourage you to put it under %Tomcat_home%/conf/myKeystore.p12.

4. Configure Tomcat

Tomcat configuration file is located in %Tomcat_home%/conf/server.xml. Find this section:

<!-- Define a SSL HTTP/1.1 Connector on port 8443
   This connector uses the BIO implementation that requires the JSSE
   style configuration. When using the APR/native implementation, the
   OpenSSL style configuration is required as described in the APR/native
   documentation -->

And uncomment the configuration below it. I will use the default 443 port (not the suggested 8443) and add four green lines specific to myKeystore:

<Connector port="443" protocol="org.apache.coyote.http11.Http11Protocol"
  maxThreads="150" SSLEnabled="true" scheme="https" secure="true"
  clientAuth="false" sslProtocol="TLS" 

5. Test it

Start Tomcat and go to the:


Your browser will probably warn you about the untrusted certificate:


6. Verify the CN (Common Name)

The Common Name is the url I provided when creating keytool: If this particular address is used in a browser, the browser will not warn you. If you’ll open the


instead, the browser will warn you also that the url entered does not match the url provided on certificate creation.

Note: Don’t use Self_signed certificates in production! Use it only in test / dev environment

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3 responses

14 12 2014
SSL Certificate with Subject Alternate Names | Looks OK!

[…] post is a continuation of Creating HTTPS SSL Self Signed certificate. SSL Certificates are created for one particular ‘cn’. This can be your domain name […]

4 06 2015
Diogo Souza (@diogosouzac)

Great post. Thank you.

Just one fix: We need to access the URL as with the port included…

20 07 2015

Nice step by step instructions, great posts. Only thing is that you have mismatching name in “keytool -list” command i.e. keystore.p12 versus myKeystore.p12 in “keytool -genkey” command. Best wishes :)

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