implement single sign-on token generation - resolves #12

build.gradle

@@ -37,6 +37,7 @@ dependencies {
     compile group: 'org.apache.httpcomponents', name: 'httpclient', version: '4.5.2'
     compile group: 'org.apache.httpcomponents', name: 'httpmime', version: '4.5.2'
     compile group: 'com.mashape.unirest', name: 'unirest-java', version: '1.4.9'
+    compile 'com.auth0:java-jwt:3.3.0'
 
     compile group: 'org.slf4j', name: 'slf4j-api', version: '1.7.12'
 

src/main/java/com/invoiced/exception/SingleSignOnException.java

@@ -0,0 +1,9 @@
+package com.invoiced.exception;
+
+public class SingleSignOnException extends InvoicedException {
+	private static final long serialVersionUID = 1L;
+
+	public SingleSignOnException(Throwable cause) {
+		super(cause);
+	}
+}

src/main/java/com/invoiced/util/SingleSignOn.java

@@ -0,0 +1,33 @@
+package com.invoiced.util;
+
+import java.io.UnsupportedEncodingException;
+import java.util.Date;
+
+import com.auth0.jwt.JWT;
+import com.auth0.jwt.algorithms.Algorithm;
+import com.invoiced.exception.SingleSignOnException;
+
+public class SingleSignOn {
+
+	private final String ssoKey;
+
+	public SingleSignOn(String ssoKey) {
+		this.ssoKey = ssoKey;
+	}
+
+	public String generateToken(int customerId, int ttlSeconds) throws SingleSignOnException {
+		try {
+			Algorithm algorithm = Algorithm.HMAC256(this.ssoKey);
+
+			long expiresAtMs = (long) (System.currentTimeMillis() + ttlSeconds * 1000.0);
+			Date expiresAt = new Date(expiresAtMs);
+
+			return JWT.create().withIssuer("Invoiced Java").withIssuedAt(new Date())
+					.withSubject(Integer.toString(customerId)).withExpiresAt(expiresAt).sign(algorithm);
+		} catch (IllegalArgumentException e) {
+			throw new SingleSignOnException(e);
+		} catch (UnsupportedEncodingException e) {
+			throw new SingleSignOnException(e);
+		}
+	}
+}

src/test/java/com/invoiced/util/SingleSignOnTest.java

@@ -0,0 +1,54 @@
+package com.invoiced.util;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+import java.io.UnsupportedEncodingException;
+
+import org.junit.Test;
+
+import com.auth0.jwt.JWT;
+import com.auth0.jwt.JWTVerifier;
+import com.auth0.jwt.algorithms.Algorithm;
+import com.auth0.jwt.exceptions.JWTVerificationException;
+import com.auth0.jwt.interfaces.DecodedJWT;
+import com.invoiced.exception.SingleSignOnException;
+
+public class SingleSignOnTest {
+
+	@Test
+	public void testGenerateToken() {
+		String secret = "8baa4dbc338a54bbf7696eef3ee4aa2daadd61bba85fcfe8df96c7cfa227c43";
+		SingleSignOn sso = new SingleSignOn(secret);
+		String token = null;
+		try {
+			token = sso.generateToken(1234, 3600);
+		} catch (SingleSignOnException e) {
+			e.printStackTrace();
+			fail();
+		}
+
+		Algorithm algorithm = null;
+		try {
+			algorithm = Algorithm.HMAC256(secret);
+		} catch (IllegalArgumentException e) {
+			e.printStackTrace();
+			fail();
+		} catch (UnsupportedEncodingException e) {
+			e.printStackTrace();
+			fail();
+		}
+
+		JWTVerifier verifier = JWT.require(algorithm).withIssuer("Invoiced Java").build();
+		DecodedJWT jwt = null;
+		try {
+			jwt = verifier.verify(token);
+		} catch (JWTVerificationException e) {
+			e.printStackTrace();
+			fail();
+		}
+
+		assertEquals("1234", jwt.getSubject());
+	}
+
+}