Configuring Spring Oauth2 with JWT & asymmetric RSA keypair

Step 1: Generate RSA key pair.

Here are the steps I took to create my RSA key pairs with Java keytoolcommand. Although I did this to configure my spring oauth2 jwt application, of course, it is not only restricted to that.

Lets create our java keystore(.jks) file:

$
keytool -genkeypair -alias mytestkey -keyalg RSA \

-dname "CN=Web Server,OU=Unit,O=Organization,L=City,S=State,C=US" \

-keypass changeme -keystore server.jks -storepass letmein

We generated a keypair named mytestkey with an RSA algorithm.
Option -keypass changeme is to access the specific keypair, which is mytestkey in
our case & -storepass letmein is to access the whole keystore file.

Export public key certificate file.

$
keytool -export -keystore server.jks -alias mytestkey -file example.cer

With this certificate file we can find get our public key in the next section.

Using openssl to
print the public key.

openssl
x509 -inform der -in example.cer -pubkey -noout

This command will show the public key:

-----BEGIN
PUBLIC KEY-----

MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA3Kd1vQNTLHLVhyMR0JHj

Q3CxJ9Roi6aZTzUk/HDerxJ+1ey8CdX4zf8bFA9Fh21KTo
4000
jw87yt76A6GpCuru6P

zxCou0GLPwFwKCS1SFcsysOMSxRAhgIssjujGnbC2Q0XPDpsGYJVavnHGZ7cI7Hn

sXqHcL0dmbgEfI7NR7wCGHoo1NxjfwOQXtCGH3w/Tg2BLA3HNyRclrCfJuS3aj0y

tr7tOWdzgguztH6E4xoqKdn7FEMMtBEsggw7Z4H8uziUy37Z7iOMTdmwZvbpMrns

IUZElqnYcRFYLPRH5xsSl1Y129fAbW03WW63agzy9DWO5HhT44ePJDrkZqsEaHKw

/QIDAQAB

-----END PUBLIC KEY-----

Another way to achieve this using java code, which is bit more complex, is:

This code was inspired by 

spring
oauth2

s 

JwtAccessTokenConverter

.

Step 2: Configure Spring Oauth2

Authorization server:.

Resource Server:

In your 

application.yml

 file(note
that spacing is messed up below, you should have a proper spacing):

spring:

  oauth2:

    resource:

      jwt:

        keyValue: |

          —–BEGIN PUBLIC KEY—–

          MIIBIjANBgkqhkiG9…

          —–END PUBLIC KEY—–