Add authorization server sample

servlet/spring-boot/java/oauth2/authorization-server/README.adoc

@@ -0,0 +1,161 @@
+= OAuth 2.0 Authorization Server Sample
+
+This sample demonstrates Authorization Server with the `client_credentials` grant type. This authorization server is configured to generate JWT tokens signed with the `RS256` algorithm.
+
+* <<running-the-tests, Running the tests>>
+* <<running-the-app, Running the app>>
+* <<testing-with-a-resource-server, Testing with a resource server>>
+
+[[running-the-tests]]
+== Running the tests
+
+To run the tests, do:
+
+```bash
+./gradlew integrationTest
+```
+
+Or import the project into your IDE and run `OAuth2AuthorizationServerApplicationTests` from there.
+
+=== What is it doing?
+
+The tests are making requests to the token endpoint with the `client_credentials` grant type using the `client_secret_basic` authentication method, and subsequently verifying them using the token introspection endpoint.
+
+The introspection endpoint response is used to verify the token (decode the JWT in this case), returning the payload including the requested scope:
+
+```json
+{
+    "active": true,
+    "aud": [
+        "messaging-client"
+    ],
+    "client_id": "messaging-client",
+    "exp": 1627070941,
+    "iat": 1627070641,
+    "iss": "http://localhost:9000",
+    "jti": "987599e3-1048-4fe8-89df-ad113aef2d6c",
+    "nbf": 1627070641,
+    "scope": "message:read",
+    "sub": "messaging-client",
+    "token_type": "Bearer"
+}
+```
+
+Note that Spring Security does not require the token introspection endpoint when configured to use the Bearer scheme with JWTs, this is simply used for demonstration purposes.
+
+[[running-the-app]]
+== Running the app
+
+To run as a stand-alone application, do:
+
+```bash
+./gradlew bootRun
+```
+
+Or import the project into your IDE and run `OAuth2AuthorizationServerApplication` from there.
+
+Once it is up and running, you can issue the following request:
+
+```bash
+curl -X POST messaging-client:secret@localhost:9000/oauth2/token -d "grant_type=client_credentials" -d "scope=message:read"
+```
+
+This returns something like the following:
+
+```json
+{
+    "access_token": "eyJraWQiOiI4YWY4Zjc2Zi0zMTdkLTQxZmYtYWY5Yi1hZjg5NDg4ODM5YzciLCJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJtZXNzYWdpbmctY2xpZW50IiwiYXVkIjoibWVzc2FnaW5nLWNsaWVudCIsIm5iZiI6MTYyNzMzNDQ1MCwic2NvcGUiOlsibWVzc2FnZTpyZWFkIl0sImlzcyI6Imh0dHA6XC9cL2xvY2FsaG9zdDo5MDAwIiwiZXhwIjoxNjI3MzM0NzUwLCJpYXQiOjE2MjczMzQ0NTAsImp0aSI6IjBiYjYwZjhkLWIzNjItNDk0MC05MGRmLWZhZDg4N2Q1Yzg1ZSJ9.O8dI67B_feRjOn6pJi5ctPJmUJCNpV77SC4OiWqmpa5UHvf4Ud6L6EFe9LKuPIRrEWi8rMdCdMBOPKQMXvxLoI3LMUPf7Yj973uvZN0E988MsKwhGwxyaa_Wam8wFlk8aQlN8SbW3cKdeH-nKloNMdwjfspovefX521mxouaMjmyXdIFrM5WZ15GZK69NIniACSatE-pc9TAjKYBDbC65jVt_zHEvDQbEkZulF2bjrGOZC8C3IbJWnlKgkcshrY44TtrGPyCp2gIS0TSUUsG00iSBBC8E8zPU-YdfaP8gB9_FwUwK9zfy_hU2Ykf2aU3eulpGDVLn2rCwFeK86Rw1w",
+    "expires_in": 299,
+    "scope": "message:read",
+    "token_type": "Bearer"
+}
+```
+
+In order to make the same token introspection request as the tests, export the access token from the response:
+
+```bash
+export TOKEN=...
+```
+
+Then issue the following request:
+
+```bash
+curl -X POST messaging-client:secret@localhost:9000/oauth2/introspect -d "token=$TOKEN"
+```
+
+Which will return something like the following:
+
+```json
+{
+    "active": true,
+    "aud": [
+        "messaging-client"
+    ],
+    "client_id": "messaging-client",
+    "exp": 1627334750,
+    "iat": 1627334450,
+    "iss": "http://localhost:9000",
+    "jti": "0bb60f8d-b362-4940-90df-fad887d5c85e",
+    "nbf": 1627334450,
+    "scope": "message:read",
+    "sub": "messaging-client",
+    "token_type": "Bearer"
+}
+```
+
+[[testing-with-a-resource-server]]
+== Testing with a resource server
+
+This sample can be used in conjunction with a resource server, such as the https://github.com/spring-projects/spring-security-samples/tree/main/servlet/spring-boot/java/oauth2/resource-server/hello-security[resource-server sample] in this project.
+
+To change the sample to point to this authorization server, simply find this property in that project's `application.yml`:
+
+```yaml
+spring:
+  security:
+    oauth2:
+      resourceserver:
+        jwt:
+          jwk-set-uri: ${mockwebserver.url}/.well-known/jwks.json
+```
+
+And change the property to:
+
+```yaml
+spring:
+  security:
+    oauth2:
+      resourceserver:
+        jwt:
+          jwk-set-uri: http://localhost:9000/oauth2/jwks
+```
+
+And then you can run that app similarly to the authorization server:
+
+```bash
+./gradlew bootRun
+```
+
+Once it is up and running, you can issue the following request:
+
+```bash
+curl -X POST messaging-client:secret@localhost:9000/oauth2/token -d "grant_type=client_credentials" -d "scope=message:read"
+```
+
+Then, export the access token from the response:
+
+```bash
+export TOKEN=...
+```
+
+Then issue the following request:
+
+```bash
+curl -H "Authorization: Bearer $TOKEN" localhost:8080
+```
+
+Which will respond with the phrase:
+
+```
+Hello, messaging-client!
+```

servlet/spring-boot/java/oauth2/authorization-server/build.gradle

@@ -0,0 +1,25 @@
+plugins {
+	id 'org.springframework.boot' version '2.5.0'
+	id 'io.spring.dependency-management' version '1.0.10.RELEASE'
+	id "nebula.integtest" version "7.0.9"
+	id 'java'
+}
+
+repositories {
+	jcenter()
+	maven { url "https://repo.spring.io/snapshot" }
+}
+
+dependencies {
+	implementation 'org.springframework.boot:spring-boot-starter-web'
+	implementation 'org.springframework.security.experimental:spring-security-oauth2-authorization-server:0.1.2'
+
+	testImplementation 'org.springframework.boot:spring-boot-starter-test'
+	testImplementation 'org.springframework.security:spring-security-test'
+
+	integTestImplementation 'net.sourceforge.htmlunit:htmlunit'
+}
+
+tasks.withType(Test).configureEach {
+	useJUnitPlatform()
+}

servlet/spring-boot/java/oauth2/authorization-server/gradle.properties

@@ -0,0 +1,2 @@
+version=5.6.0-SNAPSHOT
+spring-security.version=5.6.0-SNAPSHOT

servlet/spring-boot/java/oauth2/authorization-server/gradlew

@@ -0,0 +1,185 @@
+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=`expr $i + 1`
+    done
+    case $i in
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=`save "$@"`
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+exec "$JAVACMD" "$@"

servlet/spring-boot/java/oauth2/authorization-server/gradlew.bat

@@ -0,0 +1,104 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

servlet/spring-boot/java/oauth2/authorization-server/settings.gradle

@@ -0,0 +1 @@
+

servlet/spring-boot/java/oauth2/authorization-server/src/integTest/java/example/OAuth2AuthorizationServerApplicationITests.java

@@ -0,0 +1,184 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import java.util.Map;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.http.HttpHeaders;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.MvcResult;
+import org.springframework.test.web.servlet.request.RequestPostProcessor;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+/**
+ * Integration tests for {@link OAuth2AuthorizationServerApplication}.
+ *
+ * @author Steve Riesenberg
+ */
+@SpringBootTest
+@AutoConfigureMockMvc
+@ActiveProfiles("test")
+public class OAuth2AuthorizationServerApplicationITests {
+
+	private static final String CLIENT_ID = "messaging-client";
+
+	private static final String CLIENT_SECRET = "secret";
+
+	private final ObjectMapper objectMapper = new ObjectMapper();
+
+	@Autowired
+	private MockMvc mockMvc;
+
+	@Test
+	void performTokenRequestWhenValidClientCredentialsThenOk() throws Exception {
+		// @formatter:off
+		this.mockMvc.perform(post("/oauth2/token")
+				.param("grant_type", "client_credentials")
+				.param("scope", "message:read")
+				.with(basicAuth(CLIENT_ID, CLIENT_SECRET)))
+				.andExpect(status().isOk())
+				.andExpect(jsonPath("$.access_token").isString())
+				.andExpect(jsonPath("$.expires_in").isNumber())
+				.andExpect(jsonPath("$.scope").value("message:read"))
+				.andExpect(jsonPath("$.token_type").value("Bearer"));
+		// @formatter:on
+	}
+
+	@Test
+	void performTokenRequestWhenMissingScopeThenOk() throws Exception {
+		// @formatter:off
+		this.mockMvc.perform(post("/oauth2/token")
+				.param("grant_type", "client_credentials")
+				.with(basicAuth(CLIENT_ID, CLIENT_SECRET)))
+				.andExpect(status().isOk())
+				.andExpect(jsonPath("$.access_token").isString())
+				.andExpect(jsonPath("$.expires_in").isNumber())
+				.andExpect(jsonPath("$.scope").value("message:read message:write"))
+				.andExpect(jsonPath("$.token_type").value("Bearer"));
+		// @formatter:on
+	}
+
+	@Test
+	void performTokenRequestWhenInvalidClientCredentialsThenUnauthorized() throws Exception {
+		// @formatter:off
+		this.mockMvc.perform(post("/oauth2/token")
+				.param("grant_type", "client_credentials")
+				.param("scope", "message:read")
+				.with(basicAuth("bad", "password")))
+				.andExpect(status().isUnauthorized())
+				.andExpect(jsonPath("$.error").value("invalid_client"));
+		// @formatter:on
+	}
+
+	@Test
+	void performTokenRequestWhenMissingGrantTypeThenUnauthorized() throws Exception {
+		// @formatter:off
+		this.mockMvc.perform(post("/oauth2/token")
+				.with(basicAuth("bad", "password")))
+				.andExpect(status().isUnauthorized())
+				.andExpect(jsonPath("$.error").value("invalid_client"));
+		// @formatter:on
+	}
+
+	@Test
+	void performIntrospectionRequestWhenValidTokenThenOk() throws Exception {
+		// @formatter:off
+		this.mockMvc.perform(post("/oauth2/introspect")
+				.param("token", getAccessToken())
+				.with(basicAuth(CLIENT_ID, CLIENT_SECRET)))
+				.andExpect(status().isOk())
+				.andExpect(jsonPath("$.active").value("true"))
+				.andExpect(jsonPath("$.aud[0]").value(CLIENT_ID))
+				.andExpect(jsonPath("$.client_id").value(CLIENT_ID))
+				.andExpect(jsonPath("$.exp").isNumber())
+				.andExpect(jsonPath("$.iat").isNumber())
+				.andExpect(jsonPath("$.iss").value("http://localhost:9000"))
+				.andExpect(jsonPath("$.jti").isString())
+				.andExpect(jsonPath("$.nbf").isNumber())
+				.andExpect(jsonPath("$.scope").value("message:read"))
+				.andExpect(jsonPath("$.sub").value(CLIENT_ID))
+				.andExpect(jsonPath("$.token_type").value("Bearer"));
+		// @formatter:on
+	}
+
+	@Test
+	void performIntrospectionRequestWhenInvalidCredentialsThenUnauthorized() throws Exception {
+		// @formatter:off
+		this.mockMvc.perform(post("/oauth2/introspect")
+				.param("token", getAccessToken())
+				.with(basicAuth("bad", "password")))
+				.andExpect(status().isUnauthorized())
+				.andExpect(jsonPath("$.error").value("invalid_client"));
+		// @formatter:on
+	}
+
+	private String getAccessToken() throws Exception {
+		// @formatter:off
+		MvcResult mvcResult = this.mockMvc.perform(post("/oauth2/token")
+				.param("grant_type", "client_credentials")
+				.param("scope", "message:read")
+				.with(basicAuth(CLIENT_ID, CLIENT_SECRET)))
+				.andExpect(status().isOk())
+				.andExpect(jsonPath("$.access_token").exists())
+				.andReturn();
+		// @formatter:on
+
+		String tokenResponseJson = mvcResult.getResponse().getContentAsString();
+		Map<String, Object> tokenResponse = this.objectMapper.readValue(tokenResponseJson, new TypeReference<>() {
+		});
+
+		return tokenResponse.get("access_token").toString();
+	}
+
+	private static BasicAuthenticationRequestPostProcessor basicAuth(String username, String password) {
+		return new BasicAuthenticationRequestPostProcessor(username, password);
+	}
+
+	private static final class BasicAuthenticationRequestPostProcessor implements RequestPostProcessor {
+
+		private final String username;
+
+		private final String password;
+
+		private BasicAuthenticationRequestPostProcessor(String username, String password) {
+			this.username = username;
+			this.password = password;
+		}
+
+		@Override
+		public MockHttpServletRequest postProcessRequest(MockHttpServletRequest request) {
+			HttpHeaders headers = new HttpHeaders();
+			headers.setBasicAuth(this.username, this.password);
+			request.addHeader("Authorization", headers.getFirst("Authorization"));
+			return request;
+		}
+
+	}
+
+}

servlet/spring-boot/java/oauth2/authorization-server/src/main/java/example/Jwks.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import java.security.KeyPair;
+import java.security.interfaces.RSAPrivateKey;
+import java.security.interfaces.RSAPublicKey;
+import java.util.UUID;
+
+import com.nimbusds.jose.jwk.RSAKey;
+
+/**
+ * Utils for generating JWKs.
+ *
+ * @author Joe Grandja
+ */
+final class Jwks {
+
+	private Jwks() {
+	}
+
+	static RSAKey generateRsa() {
+		KeyPair keyPair = KeyGeneratorUtils.generateRsaKey();
+		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
+		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
+		// @formatter:off
+		return new RSAKey.Builder(publicKey)
+				.privateKey(privateKey)
+				.keyID(UUID.randomUUID().toString())
+				.build();
+		// @formatter:on
+	}
+
+}

servlet/spring-boot/java/oauth2/authorization-server/src/main/java/example/KeyGeneratorUtils.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example;
+
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+
+/**
+ * Utils for generating keys.
+ *
+ * @author Joe Grandja
+ */
+final class KeyGeneratorUtils {
+
+	private KeyGeneratorUtils() {
+	}
+
+	static KeyPair generateRsaKey() {
+		KeyPair keyPair;
+		try {
+			KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
+			keyPairGenerator.initialize(2048);
+			keyPair = keyPairGenerator.generateKeyPair();
+		}
+		catch (Exception ex) {
+			throw new IllegalStateException(ex);
+		}
+		return keyPair;
+	}
+
+}

servlet/spring-boot/java/oauth2/authorization-server/src/main/java/example/OAuth2AuthorizationServerApplication.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * OAuth Authorization Server Application.
+ *
+ * @author Steve Riesenberg
+ */
+@SpringBootApplication
+public class OAuth2AuthorizationServerApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(OAuth2AuthorizationServerApplication.class, args);
+	}
+
+}

servlet/spring-boot/java/oauth2/authorization-server/src/main/java/example/OAuth2AuthorizationServerSecurityConfiguration.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+
+import com.nimbusds.jose.JWSAlgorithm;
+import com.nimbusds.jose.jwk.JWKSet;
+import com.nimbusds.jose.jwk.RSAKey;
+import com.nimbusds.jose.jwk.source.ImmutableJWKSet;
+import com.nimbusds.jose.jwk.source.JWKSource;
+import com.nimbusds.jose.proc.JWSKeySelector;
+import com.nimbusds.jose.proc.JWSVerificationKeySelector;
+import com.nimbusds.jose.proc.SecurityContext;
+import com.nimbusds.jwt.proc.ConfigurableJWTProcessor;
+import com.nimbusds.jwt.proc.DefaultJWTProcessor;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.security.config.annotation.web.configuration.OAuth2AuthorizationServerConfiguration;
+import org.springframework.security.config.http.SessionCreationPolicy;
+import org.springframework.security.oauth2.core.AuthorizationGrantType;
+import org.springframework.security.oauth2.core.ClientAuthenticationMethod;
+import org.springframework.security.oauth2.jwt.JwtDecoder;
+import org.springframework.security.oauth2.jwt.NimbusJwtDecoder;
+import org.springframework.security.oauth2.server.authorization.client.InMemoryRegisteredClientRepository;
+import org.springframework.security.oauth2.server.authorization.client.RegisteredClient;
+import org.springframework.security.oauth2.server.authorization.client.RegisteredClientRepository;
+import org.springframework.security.oauth2.server.authorization.config.ProviderSettings;
+import org.springframework.security.web.SecurityFilterChain;
+
+/**
+ * OAuth Authorization Server Configuration.
+ *
+ * @author Steve Riesenberg
+ */
+@EnableWebSecurity
+public class OAuth2AuthorizationServerSecurityConfiguration {
+
+	@Bean
+	public SecurityFilterChain authorizationServerSecurityFilterChain(HttpSecurity http) throws Exception {
+		OAuth2AuthorizationServerConfiguration.applyDefaultSecurity(http);
+
+		// @formatter:off
+		http
+			.sessionManagement((sessionManagement) ->
+				sessionManagement
+					.sessionCreationPolicy(SessionCreationPolicy.STATELESS)
+			);
+		// @formatter:on
+
+		return http.build();
+	}
+
+	@Bean
+	public RegisteredClientRepository registeredClientRepository() {
+		// @formatter:off
+		RegisteredClient registeredClient = RegisteredClient.withId(UUID.randomUUID().toString())
+				.clientId("messaging-client")
+				.clientSecret("{noop}secret")
+				.clientAuthenticationMethod(ClientAuthenticationMethod.BASIC)
+				.authorizationGrantType(AuthorizationGrantType.CLIENT_CREDENTIALS)
+				.scope("message:read")
+				.scope("message:write")
+				.clientSettings((clientSettings) -> clientSettings.requireUserConsent(true))
+				.build();
+		// @formatter:on
+
+		return new InMemoryRegisteredClientRepository(registeredClient);
+	}
+
+	@Bean
+	public JWKSource<SecurityContext> jwkSource() {
+		RSAKey rsaKey = Jwks.generateRsa();
+		JWKSet jwkSet = new JWKSet(rsaKey);
+		return new ImmutableJWKSet<>(jwkSet);
+	}
+
+	@Bean
+	public JwtDecoder jwtDecoder(JWKSource<SecurityContext> jwkSource) {
+		Set<JWSAlgorithm> jwsAlgs = new HashSet<>();
+		jwsAlgs.addAll(JWSAlgorithm.Family.RSA);
+		jwsAlgs.addAll(JWSAlgorithm.Family.EC);
+		jwsAlgs.addAll(JWSAlgorithm.Family.HMAC_SHA);
+		ConfigurableJWTProcessor<SecurityContext> jwtProcessor = new DefaultJWTProcessor<>();
+		JWSKeySelector<SecurityContext> jwsKeySelector = new JWSVerificationKeySelector<>(jwsAlgs, jwkSource);
+		jwtProcessor.setJWSKeySelector(jwsKeySelector);
+		// Override the default Nimbus claims set verifier as NimbusJwtDecoder handles it
+		// instead
+		jwtProcessor.setJWTClaimsSetVerifier((claims, context) -> {
+		});
+		return new NimbusJwtDecoder(jwtProcessor);
+	}
+
+	@Bean
+	public ProviderSettings providerSettings() {
+		return new ProviderSettings().issuer("http://localhost:9000");
+	}
+
+}

servlet/spring-boot/java/oauth2/authorization-server/src/main/resources/application.yml

@@ -0,0 +1,2 @@
+server:
+  port: 9000

settings.gradle

@@ -46,6 +46,7 @@ include ":servlet:spring-boot:java:hello-security"
 include ":servlet:spring-boot:java:hello-security-explicit"
 include ":servlet:spring-boot:java:jwt:login"
 include ":servlet:spring-boot:java:ldap"
+include ":servlet:spring-boot:java:oauth2:authorization-server"
 include ":servlet:spring-boot:java:oauth2:login"
 include ":servlet:spring-boot:java:oauth2:resource-server:hello-security"
 include ":servlet:spring-boot:java:oauth2:resource-server:jwe"