OAuth2 with Asymmetric Approache

I have implemented a resource server and authorization server with spring cloud oauth2. When I implemented the OAuth application by using the default approach (without using asymmetric or symmetric approach) then the default token is generated by the authorization server and when I have to communicate with the resource server and the authorization server then the following properties can be used in the resource server config file.

resource-server.yml with default

security:
  oauth2:
    client:
      client-id: web
      client-secret: *****
    resource:
      token-info-uri: "http://localhost:9092/oauth/check_token"

When I use an asymmetric approach to sign the token with the private key in the authorization server and use the public key to validate the token in the resource server with the following property security:jwt:public-key: classpath:public.txt then the following unauthorized response has occurred when I call the resource from the resource server.

resource-server.yml with asymmetric

security:
  jwt:
    public-key: classpath:public.txt

API Endpoint

http://localhost:9090/user?Authorization=bearer **********

Response

{
"error": "invalid_token",
"error_description": "Cannot convert access token to JSON"
}

Note - when I use client and token-info-uri properties with an asymmetric approach in the resource-server.yml then the following error has occurred.

Method springSecurityFilterChain in org.springframework.security.config.annotation.web.configuration.WebSecurityConfiguration required a single bean, but 2 were found:
	- tokenServices: defined by method 'tokenServices' in class path resource [com/benz/resource/api/config/ResourceServerConfiguration.class]
	- remoteTokenServices: defined by method 'remoteTokenServices' in class path resource [org/springframework/boot/autoconfigure/security/oauth2/resource/ResourceServerTokenServicesConfiguration$RemoteTokenServicesConfiguration$TokenInfoServicesConfiguration.

I have to clarify the following question

1. Without using token-info-uri and client properties how does the resource server identify the particular authorization server?.

2. why does the unauthorized error has occurred (which is mentioned in the above)?

ResourceServerConfig class

@Configuration
public class ResourceServerConfiguration extends ResourceServerConfigurerAdapter {

    @Value("${security.jwt.public-key}")
    private Resource publicKey;

    private TokenStore tokenStore;


    @Override
    public void configure(ResourceServerSecurityConfigurer resources) throws Exception {
        resources.tokenStore(tokenStore());
    }

    @Bean
    public DefaultTokenServices tokenServices(TokenStore tokenStore)
    {
        DefaultTokenServices tokenServices=new DefaultTokenServices();
        tokenServices.setTokenStore(tokenStore);
        return tokenServices;
    }

    @Bean
    public TokenStore tokenStore() throws Exception
    {
        if(tokenStore==null)
            tokenStore=new JwtTokenStore(tokenConverter());

        return tokenStore;
    }

    private JwtAccessTokenConverter tokenConverter() throws Exception
    {
        JwtAccessTokenConverter converter=new JwtAccessTokenConverter();
        converter.setVerifierKey(getPublicKeyAsString());
        return converter;
    }


    private String getPublicKeyAsString() throws Exception
    {
        return IOUtils.toString(publicKey.getInputStream(),UTF_8);
    }
}

Github link for

resource-server-implementation

authorization-server-implemetation

If you need more details please comment it then I can update

I have solved the issue. In my case, tokenConverter method is called at the time of JwtTokenStore bean instance created. I have changed the approach to create the bean instance for JwtAccessTokenConverter separately by adding @Bean annotation. In that case, it is worked without any interruption.

    @Bean
    public JwtAccessTokenConverter tokenConverter() throws Exception
    {
        JwtAccessTokenConverter converter=new JwtAccessTokenConverter();
        converter.setVerifierKey(getPublicKeyAsString());
        return converter;
    }