7 jwt service implementation

apigateway/pom.xml

@@ -66,7 +66,7 @@
 		<dependency>
 			<groupId>io.jsonwebtoken</groupId>
 			<artifactId>jjwt-jackson</artifactId>
-			<version>0.12.5</version>
+			<version>0.13.0</version>
 			<scope>runtime</scope>
 		</dependency>
 

apigateway/src/main/java/vaultweb/apigateway/model/User.java

@@ -1,9 +1,9 @@
 package vaultweb.apigateway.model;
 
 import jakarta.persistence.Entity;
-import jakarta.persistence.Id;
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
 import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.NoArgsConstructor;
@@ -13,11 +13,22 @@
 @AllArgsConstructor
 @NoArgsConstructor
 public class User {
+
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private int id;
+
     private String name;
     private String email;
     private String password;
 
-}
+    public static record PublicData(int id, String name, String email) {
+        public static PublicData from(User user) {
+            return new PublicData(
+                user.getId(),
+                user.getName(),
+                user.getEmail()
+            );
+        }
+    }
+}

apigateway/src/main/java/vaultweb/apigateway/service/JwtService.java

@@ -0,0 +1,112 @@
+package vaultweb.apigateway.service;
+
+import io.jsonwebtoken.Claims;
+import io.jsonwebtoken.JwtException;
+import io.jsonwebtoken.JwtParser;
+import io.jsonwebtoken.Jwts;
+import io.jsonwebtoken.io.Decoders;
+import io.jsonwebtoken.security.Keys;
+import java.util.Date;
+import javax.crypto.SecretKey;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Service;
+
+@Service
+public class JwtService {
+
+    @Value("${jwt.secret}")
+    private String SECRET_KEY;
+
+    private JwtParser parser = Jwts.parser()
+        .verifyWith(getSigningKey())
+        .build();
+
+    private static final long EXPIRATION_TIME_MILLIS = 3600000; // 1 hour
+
+    /**
+     * Creates a secret key to sign JWT tokens.
+     * <p>
+     * It always creates the exact same key, with the same secret key.
+     * This method decodes the secret key from the application.properties file into a BASE 64 encoded string.
+     * It is done to ensure that the secret is properly formed, since {@code SECRET_KEY} could contain non UTF-8 characters.
+     * @return {@code SecretKey}
+     */
+    private SecretKey getSigningKey() {
+        byte[] keyBytes = Decoders.BASE64.decode(SECRET_KEY);
+        return Keys.hmacShaKeyFor(keyBytes);
+    }
+
+    /**
+     * Checks if the token is valid.
+     * <p>
+     * It verifies the token's signature and expiration time.
+     * @param token the token to be validated
+     * @return {@code true} if the token is valid, {@code false} otherwise
+     */
+    public boolean isValid(final String token) {
+        return isUnmodified(token) && !isExpired(token);
+    }
+
+    /**
+     * Generates a JWT token.
+     * <p>
+     * The generated token is valid for {@code EXPIRATION_TIME_MILLIS} milliseconds.
+     * Additionally, the token is always signed with the {@code SECRET_KEY} to ensure its integrity.
+     * The token is always going to contain the user's id and name.
+     * @param id of the user
+     * @param username of the user
+     * @return the generated signed jwt token as a {@link String}
+     */
+    public String generateToken(final Integer id, final String username) {
+        return Jwts.builder()
+            .subject(username)
+            .claim("userId", id)
+            .issuedAt(new Date())
+            .expiration(
+                new Date(System.currentTimeMillis() + EXPIRATION_TIME_MILLIS)
+            )
+            .signWith(getSigningKey())
+            .compact();
+    }
+
+    /**
+     * Extracts all claims from the given token.
+     * @param token the token to extract claims from
+     * @return the extracted claims as a {@link Claims} object
+     */
+    private Claims extractAllClaims(final String token) {
+        return this.parser.parseSignedClaims(token).getPayload();
+    }
+
+    /**
+     * Extracts the expiration date of the token.
+     * @param token the token to extract claims from
+     * @return the expiration date of the token and return it as a {@link Date}
+     */
+    private Date extractExpiration(final String token) {
+        return extractAllClaims(token).getExpiration();
+    }
+
+    /**
+     * Checks if the token is expired.
+     * @param token the token to check
+     * @return true if the token is expired and false otherwise
+     */
+    private boolean isExpired(final String token) {
+        return this.extractExpiration(token).before(new Date());
+    }
+
+    /**
+     * Checks if the token is unmodified.
+     * @param token the token to check
+     * @return true if the token is unmodified and false otherwise
+     */
+    private boolean isUnmodified(final String token) {
+        try {
+            this.parser.parseSignedClaims(token);
+            return true;
+        } catch (final JwtException e) {
+            return false;
+        }
+    }
+}