This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Security 6.1.11! |
OAuth 2.0 Resource Server JWT
Minimal Dependencies for JWT
Most Resource Server support is collected into spring-security-oauth2-resource-server
.
However, the support for decoding and verifying JWTs is in spring-security-oauth2-jose
, meaning that both are necessary to have a working resource server that supports JWT-encoded Bearer Tokens.
Minimal Configuration for JWTs
When using Spring Boot, configuring an application as a resource server consists of two basic steps. First, include the needed dependencies. Second, indicate the location of the authorization server.
Specifying the Authorization Server
In a Spring Boot application, you need to specify which authorization server to use:
spring:
security:
oauth2:
resourceserver:
jwt:
issuer-uri: https://idp.example.com/issuer
Where idp.example.com/issuer
is the value contained in the iss
claim for JWT tokens that the authorization server issues.
This resource server uses this property to further self-configure, discover the authorization server’s public keys, and subsequently validate incoming JWTs.
To use the |
Startup Expectations
When this property and these dependencies are used, Resource Server automatically configures itself to validate JWT-encoded Bearer Tokens.
It achieves this through a deterministic startup process:
-
Hit the Provider Configuration or Authorization Server Metadata endpoint, processing the response for the
jwks_url
property. -
Configure the validation strategy to query
jwks_url
for valid public keys. -
Configure the validation strategy to validate each JWT’s
iss
claim againstidp.example.com
.
A consequence of this process is that the authorization server must be receiving requests in order for Resource Server to successfully start up.
If the authorization server is down when Resource Server queries it (given appropriate timeouts), then startup fails. |
Runtime Expectations
Once the application is started up, Resource Server tries to process any request that contains an Authorization: Bearer
header:
GET / HTTP/1.1
Authorization: Bearer some-token-value # Resource Server will process this
So long as this scheme is indicated, Resource Server tries to process the request according to the Bearer Token specification.
Given a well-formed JWT, Resource Server:
-
Validates its signature against a public key obtained from the
jwks_url
endpoint during startup and matched against the JWTs header. -
Validates the JWTs
exp
andnbf
timestamps and the JWTsiss
claim. -
Maps each scope to an authority with the prefix
SCOPE_
.
As the authorization server makes available new keys, Spring Security automatically rotates the keys used to validate the JWT tokens. |
By default, the resulting Authentication#getPrincipal
is a Spring Security Jwt
object, and Authentication#getName
maps to the JWT’s sub
property, if one is present.
From here, consider jumping to:
Specifying the Authorization Server JWK Set Uri Directly
If the authorization server does not support any configuration endpoints, or if Resource Server must be able to start up independently from the authorization server, you can supply jwk-set-uri
as well:
spring:
security:
oauth2:
resourceserver:
jwt:
issuer-uri: https://idp.example.com
jwk-set-uri: https://idp.example.com/.well-known/jwks.json
The JWK Set uri is not standardized, but you can typically find it in the authorization server’s documentation. |
Consequently, Resource Server does not ping the authorization server at startup.
We still specify the issuer-uri
so that Resource Server still validates the iss
claim on incoming JWTs.
You can supply this property directly on the DSL. |
Overriding or Replacing Boot Auto Configuration
Spring Boot generates two @Bean
objects on Resource Server’s behalf.
The first bean is a SecurityWebFilterChain
that configures the application as a resource server. When including spring-security-oauth2-jose
, this SecurityWebFilterChain
looks like:
-
Java
-
Kotlin
@Bean
SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
http
.authorizeExchange(exchanges -> exchanges
.anyExchange().authenticated()
)
.oauth2ResourceServer(OAuth2ResourceServerSpec::jwt)
return http.build();
}
@Bean
fun springSecurityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
return http {
authorizeExchange {
authorize(anyExchange, authenticated)
}
oauth2ResourceServer {
jwt { }
}
}
}
If the application does not expose a SecurityWebFilterChain
bean, Spring Boot exposes the default one (shown in the preceding listing).
To replace it, expose the @Bean
within the application:
-
Java
-
Kotlin
@Bean
SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
http
.authorizeExchange(exchanges -> exchanges
.pathMatchers("/message/**").hasAuthority("SCOPE_message:read")
.anyExchange().authenticated()
)
.oauth2ResourceServer(oauth2 -> oauth2
.jwt(withDefaults())
);
return http.build();
}
@Bean
fun springSecurityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
return http {
authorizeExchange {
authorize("/message/**", hasAuthority("SCOPE_message:read"))
authorize(anyExchange, authenticated)
}
oauth2ResourceServer {
jwt { }
}
}
}
The preceding configuration requires the scope of message:read
for any URL that starts with /messages/
.
Methods on the oauth2ResourceServer
DSL also override or replace auto configuration.
For example, the second @Bean
Spring Boot creates is a ReactiveJwtDecoder
, which decodes String
tokens into validated instances of Jwt
:
-
Java
-
Kotlin
@Bean
public ReactiveJwtDecoder jwtDecoder() {
return ReactiveJwtDecoders.fromIssuerLocation(issuerUri);
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return ReactiveJwtDecoders.fromIssuerLocation(issuerUri)
}
Calling |
Its configuration can be overridden by using jwkSetUri()
or replaced by using decoder()
.
Using jwkSetUri()
You can configure an authorization server’s JWK Set URI as a configuration property or supply it in the DSL:
-
Java
-
Kotlin
@Bean
SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
http
.authorizeExchange(exchanges -> exchanges
.anyExchange().authenticated()
)
.oauth2ResourceServer(oauth2 -> oauth2
.jwt(jwt -> jwt
.jwkSetUri("https://idp.example.com/.well-known/jwks.json")
)
);
return http.build();
}
@Bean
fun springSecurityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
return http {
authorizeExchange {
authorize(anyExchange, authenticated)
}
oauth2ResourceServer {
jwt {
jwkSetUri = "https://idp.example.com/.well-known/jwks.json"
}
}
}
}
Using jwkSetUri()
takes precedence over any configuration property.
Using decoder()
decoder()
is more powerful than jwkSetUri()
, because it completely replaces any Spring Boot auto-configuration of JwtDecoder
:
-
Java
-
Kotlin
@Bean
SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
http
.authorizeExchange(exchanges -> exchanges
.anyExchange().authenticated()
)
.oauth2ResourceServer(oauth2 -> oauth2
.jwt(jwt -> jwt
.decoder(myCustomDecoder())
)
);
return http.build();
}
@Bean
fun springSecurityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
return http {
authorizeExchange {
authorize(anyExchange, authenticated)
}
oauth2ResourceServer {
jwt {
jwtDecoder = myCustomDecoder()
}
}
}
}
This is handy when you need deeper configuration, such as validation.
Exposing a ReactiveJwtDecoder
@Bean
Alternately, exposing a ReactiveJwtDecoder
@Bean
has the same effect as decoder()
:
You can construct one with a jwkSetUri
like so:
-
Java
-
Kotlin
@Bean
public ReactiveJwtDecoder jwtDecoder() {
return NimbusReactiveJwtDecoder.withJwkSetUri(jwkSetUri).build();
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return NimbusReactiveJwtDecoder.withJwkSetUri(jwkSetUri).build()
}
or you can use the issuer and have NimbusReactiveJwtDecoder
look up the jwkSetUri
when build()
is invoked, like the following:
-
Java
-
Kotlin
@Bean
public ReactiveJwtDecoder jwtDecoder() {
return NimbusReactiveJwtDecoder.withIssuerLocation(issuer).build();
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return NimbusReactiveJwtDecoder.withIssuerLocation(issuer).build()
}
Or, if the defaults work for you, you can also use JwtDecoders
, which does the above in addition to configuring the decoder’s validator:
-
Java
-
Kotlin
@Bean
public ReactiveJwtDecoder jwtDecoder() {
return ReactiveJwtDecoders.fromIssuerLocation(issuer);
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return ReactiveJwtDecoders.fromIssuerLocation(issuer)
}
Configuring Trusted Algorithms
By default, NimbusReactiveJwtDecoder
, and hence Resource Server, trust and verify only tokens that use RS256
.
You can customize this behavior with Spring Boot or by using the NimbusJwtDecoder builder.
Customizing Trusted Algorithms with Spring Boot
The simplest way to set the algorithm is as a property:
spring:
security:
oauth2:
resourceserver:
jwt:
jws-algorithms: RS512
jwk-set-uri: https://idp.example.org/.well-known/jwks.json
Customizing Trusted Algorithms by Using a Builder
For greater power, though, we can use a builder that ships with NimbusReactiveJwtDecoder
:
-
Java
-
Kotlin
@Bean
ReactiveJwtDecoder jwtDecoder() {
return NimbusReactiveJwtDecoder.withIssuerLocation(this.issuer)
.jwsAlgorithm(RS512).build();
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return NimbusReactiveJwtDecoder.withIssuerLocation(this.issuer)
.jwsAlgorithm(RS512).build()
}
Calling jwsAlgorithm
more than once configures NimbusReactiveJwtDecoder
to trust more than one algorithm:
-
Java
-
Kotlin
@Bean
ReactiveJwtDecoder jwtDecoder() {
return NimbusReactiveJwtDecoder.withIssuerLocation(this.issuer)
.jwsAlgorithm(RS512).jwsAlgorithm(ES512).build();
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return NimbusReactiveJwtDecoder.withIssuerLocation(this.issuer)
.jwsAlgorithm(RS512).jwsAlgorithm(ES512).build()
}
Alternately, you can call jwsAlgorithms
:
-
Java
-
Kotlin
@Bean
ReactiveJwtDecoder jwtDecoder() {
return NimbusReactiveJwtDecoder.withIssuerLocation(this.jwkSetUri)
.jwsAlgorithms(algorithms -> {
algorithms.add(RS512);
algorithms.add(ES512);
}).build();
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return NimbusReactiveJwtDecoder.withIssuerLocation(this.jwkSetUri)
.jwsAlgorithms {
it.add(RS512)
it.add(ES512)
}
.build()
}
Trusting a Single Asymmetric Key
Simpler than backing a Resource Server with a JWK Set endpoint is to hard-code an RSA public key. The public key can be provided with Spring Boot or by Using a Builder.
Via Spring Boot
You can specify a key with Spring Boot:
spring:
security:
oauth2:
resourceserver:
jwt:
public-key-location: classpath:my-key.pub
Alternately, to allow for a more sophisticated lookup, you can post-process the RsaKeyConversionServicePostProcessor
:
-
Java
-
Kotlin
@Bean
BeanFactoryPostProcessor conversionServiceCustomizer() {
return beanFactory ->
beanFactory.getBean(RsaKeyConversionServicePostProcessor.class)
.setResourceLoader(new CustomResourceLoader());
}
@Bean
fun conversionServiceCustomizer(): BeanFactoryPostProcessor {
return BeanFactoryPostProcessor { beanFactory: ConfigurableListableBeanFactory ->
beanFactory.getBean<RsaKeyConversionServicePostProcessor>()
.setResourceLoader(CustomResourceLoader())
}
}
Specify your key’s location:
key.location: hfds://my-key.pub
Then autowire the value:
-
Java
-
Kotlin
@Value("${key.location}")
RSAPublicKey key;
@Value("\${key.location}")
val key: RSAPublicKey? = null
Using a Builder
To wire an RSAPublicKey
directly, use the appropriate NimbusReactiveJwtDecoder
builder:
-
Java
-
Kotlin
@Bean
public ReactiveJwtDecoder jwtDecoder() {
return NimbusReactiveJwtDecoder.withPublicKey(this.key).build();
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return NimbusReactiveJwtDecoder.withPublicKey(key).build()
}
Trusting a Single Symmetric Key
You can also use a single symmetric key.
You can load in your SecretKey
and use the appropriate NimbusReactiveJwtDecoder
builder:
-
Java
-
Kotlin
@Bean
public ReactiveJwtDecoder jwtDecoder() {
return NimbusReactiveJwtDecoder.withSecretKey(this.key).build();
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
return NimbusReactiveJwtDecoder.withSecretKey(this.key).build()
}
Configuring Authorization
A JWT that is issued from an OAuth 2.0 Authorization Server typically has either a scope
or an scp
attribute, indicating the scopes (or authorities) it has been granted — for example:
{ ..., "scope" : "messages contacts"}
When this is the case, Resource Server tries to coerce these scopes into a list of granted authorities, prefixing each scope with the string, SCOPE_
.
This means that, to protect an endpoint or method with a scope derived from a JWT, the corresponding expressions should include this prefix:
-
Java
-
Kotlin
@Bean
SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
http
.authorizeExchange(exchanges -> exchanges
.mvcMatchers("/contacts/**").hasAuthority("SCOPE_contacts")
.mvcMatchers("/messages/**").hasAuthority("SCOPE_messages")
.anyExchange().authenticated()
)
.oauth2ResourceServer(OAuth2ResourceServerSpec::jwt);
return http.build();
}
@Bean
fun springSecurityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
return http {
authorizeExchange {
authorize("/contacts/**", hasAuthority("SCOPE_contacts"))
authorize("/messages/**", hasAuthority("SCOPE_messages"))
authorize(anyExchange, authenticated)
}
oauth2ResourceServer {
jwt { }
}
}
}
You can do something similar with method security:
-
Java
-
Kotlin
@PreAuthorize("hasAuthority('SCOPE_messages')")
public Flux<Message> getMessages(...) {}
@PreAuthorize("hasAuthority('SCOPE_messages')")
fun getMessages(): Flux<Message> { }
Extracting Authorities Manually
However, there are a number of circumstances where this default is insufficient.
For example, some authorization servers do not use the scope
attribute. Instead, they have their own custom attribute.
At other times, the resource server may need to adapt the attribute or a composition of attributes into internalized authorities.
To this end, the DSL exposes jwtAuthenticationConverter()
:
-
Java
-
Kotlin
@Bean
SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
http
.authorizeExchange(exchanges -> exchanges
.anyExchange().authenticated()
)
.oauth2ResourceServer(oauth2 -> oauth2
.jwt(jwt -> jwt
.jwtAuthenticationConverter(grantedAuthoritiesExtractor())
)
);
return http.build();
}
Converter<Jwt, Mono<AbstractAuthenticationToken>> grantedAuthoritiesExtractor() {
JwtAuthenticationConverter jwtAuthenticationConverter =
new JwtAuthenticationConverter();
jwtAuthenticationConverter.setJwtGrantedAuthoritiesConverter
(new GrantedAuthoritiesExtractor());
return new ReactiveJwtAuthenticationConverterAdapter(jwtAuthenticationConverter);
}
@Bean
fun springSecurityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
return http {
authorizeExchange {
authorize(anyExchange, authenticated)
}
oauth2ResourceServer {
jwt {
jwtAuthenticationConverter = grantedAuthoritiesExtractor()
}
}
}
}
fun grantedAuthoritiesExtractor(): Converter<Jwt, Mono<AbstractAuthenticationToken>> {
val jwtAuthenticationConverter = JwtAuthenticationConverter()
jwtAuthenticationConverter.setJwtGrantedAuthoritiesConverter(GrantedAuthoritiesExtractor())
return ReactiveJwtAuthenticationConverterAdapter(jwtAuthenticationConverter)
}
jwtAuthenticationConverter()
is responsible for converting a Jwt
into an Authentication
.
As part of its configuration, we can supply a subsidiary converter to go from Jwt
to a Collection
of granted authorities.
That final converter might be something like the following GrantedAuthoritiesExtractor
:
-
Java
-
Kotlin
static class GrantedAuthoritiesExtractor
implements Converter<Jwt, Collection<GrantedAuthority>> {
public Collection<GrantedAuthority> convert(Jwt jwt) {
Collection<?> authorities = (Collection<?>)
jwt.getClaims().getOrDefault("mycustomclaim", Collections.emptyList());
return authorities.stream()
.map(Object::toString)
.map(SimpleGrantedAuthority::new)
.collect(Collectors.toList());
}
}
internal class GrantedAuthoritiesExtractor : Converter<Jwt, Collection<GrantedAuthority>> {
override fun convert(jwt: Jwt): Collection<GrantedAuthority> {
val authorities: List<Any> = jwt.claims
.getOrDefault("mycustomclaim", emptyList<Any>()) as List<Any>
return authorities
.map { it.toString() }
.map { SimpleGrantedAuthority(it) }
}
}
For more flexibility, the DSL supports entirely replacing the converter with any class that implements Converter<Jwt, Mono<AbstractAuthenticationToken>>
:
-
Java
-
Kotlin
static class CustomAuthenticationConverter implements Converter<Jwt, Mono<AbstractAuthenticationToken>> {
public AbstractAuthenticationToken convert(Jwt jwt) {
return Mono.just(jwt).map(this::doConversion);
}
}
internal class CustomAuthenticationConverter : Converter<Jwt, Mono<AbstractAuthenticationToken>> {
override fun convert(jwt: Jwt): Mono<AbstractAuthenticationToken> {
return Mono.just(jwt).map(this::doConversion)
}
}
Configuring Validation
Using minimal Spring Boot configuration, indicating the authorization server’s issuer URI, Resource Server defaults to verifying the iss
claim as well as the exp
and nbf
timestamp claims.
In circumstances where you need to customize validation needs, Resource Server ships with two standard validators and also accepts custom OAuth2TokenValidator
instances.
Customizing Timestamp Validation
JWT instances typically have a window of validity, with the start of the window indicated in the nbf
claim and the end indicated in the exp
claim.
However, every server can experience clock drift, which can cause tokens to appear to be expired to one server but not to another. This can cause some implementation heartburn, as the number of collaborating servers increases in a distributed system.
Resource Server uses JwtTimestampValidator
to verify a token’s validity window, and you can configure it with a clockSkew
to alleviate the clock drift problem:
-
Java
-
Kotlin
@Bean
ReactiveJwtDecoder jwtDecoder() {
NimbusReactiveJwtDecoder jwtDecoder = (NimbusReactiveJwtDecoder)
ReactiveJwtDecoders.fromIssuerLocation(issuerUri);
OAuth2TokenValidator<Jwt> withClockSkew = new DelegatingOAuth2TokenValidator<>(
new JwtTimestampValidator(Duration.ofSeconds(60)),
new IssuerValidator(issuerUri));
jwtDecoder.setJwtValidator(withClockSkew);
return jwtDecoder;
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
val jwtDecoder = ReactiveJwtDecoders.fromIssuerLocation(issuerUri) as NimbusReactiveJwtDecoder
val withClockSkew: OAuth2TokenValidator<Jwt> = DelegatingOAuth2TokenValidator(
JwtTimestampValidator(Duration.ofSeconds(60)),
JwtIssuerValidator(issuerUri))
jwtDecoder.setJwtValidator(withClockSkew)
return jwtDecoder
}
By default, Resource Server configures a clock skew of 60 seconds. |
Configuring a Custom Validator
You can Add a check for the aud
claim with the OAuth2TokenValidator
API:
-
Java
-
Kotlin
public class AudienceValidator implements OAuth2TokenValidator<Jwt> {
OAuth2Error error = new OAuth2Error("invalid_token", "The required audience is missing", null);
public OAuth2TokenValidatorResult validate(Jwt jwt) {
if (jwt.getAudience().contains("messaging")) {
return OAuth2TokenValidatorResult.success();
} else {
return OAuth2TokenValidatorResult.failure(error);
}
}
}
class AudienceValidator : OAuth2TokenValidator<Jwt> {
var error: OAuth2Error = OAuth2Error("invalid_token", "The required audience is missing", null)
override fun validate(jwt: Jwt): OAuth2TokenValidatorResult {
return if (jwt.audience.contains("messaging")) {
OAuth2TokenValidatorResult.success()
} else {
OAuth2TokenValidatorResult.failure(error)
}
}
}
Then, to add into a resource server, you can specifying the ReactiveJwtDecoder
instance:
-
Java
-
Kotlin
@Bean
ReactiveJwtDecoder jwtDecoder() {
NimbusReactiveJwtDecoder jwtDecoder = (NimbusReactiveJwtDecoder)
ReactiveJwtDecoders.fromIssuerLocation(issuerUri);
OAuth2TokenValidator<Jwt> audienceValidator = new AudienceValidator();
OAuth2TokenValidator<Jwt> withIssuer = JwtValidators.createDefaultWithIssuer(issuerUri);
OAuth2TokenValidator<Jwt> withAudience = new DelegatingOAuth2TokenValidator<>(withIssuer, audienceValidator);
jwtDecoder.setJwtValidator(withAudience);
return jwtDecoder;
}
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
val jwtDecoder = ReactiveJwtDecoders.fromIssuerLocation(issuerUri) as NimbusReactiveJwtDecoder
val audienceValidator: OAuth2TokenValidator<Jwt> = AudienceValidator()
val withIssuer: OAuth2TokenValidator<Jwt> = JwtValidators.createDefaultWithIssuer(issuerUri)
val withAudience: OAuth2TokenValidator<Jwt> = DelegatingOAuth2TokenValidator(withIssuer, audienceValidator)
jwtDecoder.setJwtValidator(withAudience)
return jwtDecoder
}