diff --git a/ass2-service/auth/src/main/java/dst/ass2/service/auth/impl/CachingAuthenticationService.java b/ass2-service/auth/src/main/java/dst/ass2/service/auth/impl/CachingAuthenticationService.java
new file mode 100644
index 0000000..487f8f8
--- /dev/null
+++ b/ass2-service/auth/src/main/java/dst/ass2/service/auth/impl/CachingAuthenticationService.java
@@ -0,0 +1,108 @@
+package dst.ass2.service.auth.impl;
+
+import dst.ass1.jpa.dao.impl.DAOFactory;
+import dst.ass1.jpa.model.IRider;
+import dst.ass2.service.api.auth.AuthenticationException;
+import dst.ass2.service.api.auth.NoSuchUserException;
+import dst.ass2.service.auth.ICachingAuthenticationService;
+
+import javax.annotation.PostConstruct;
+import javax.annotation.Resource;
+import javax.inject.Named;
+import javax.inject.Singleton;
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+import javax.transaction.Transactional;
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+
+import static java.lang.String.format;
+
+@Named("ICachingAuthenticationService")
+@Singleton
+public class CachingAuthenticationService implements ICachingAuthenticationService {
+    @PersistenceContext
+    private EntityManager entityManager;
+    @Resource
+    private DAOFactory daoFactory;
+
+    private final ConcurrentHashMap<String, byte[]> userCache = new ConcurrentHashMap<>();
+    private final ConcurrentHashMap<String, String> tokenCache = new ConcurrentHashMap<>();
+
+    @Transactional
+    @Override
+    public void changePassword(String email, String newPassword) throws NoSuchUserException {
+        IRider rider = daoFactory.createRiderDAO().findByEmail(email);
+        if (rider == null)
+            throw new NoSuchUserException("Could not find user with email " + email);
+        byte[] hashedPw = generateSHA1(newPassword);
+        rider.setPassword(hashedPw);
+        entityManager.merge(rider);
+        userCache.replace(email, hashedPw);
+    }
+
+    @Override
+    public String getUser(String token) {
+        return tokenCache.get(token);
+    }
+
+    @Override
+    public boolean isValid(String token) {
+        return tokenCache.containsKey(token);
+    }
+
+    @Override
+    public boolean invalidate(String token) {
+        return tokenCache.remove(token) != null;
+    }
+
+    @Transactional
+    @Override
+    public String authenticate(String email, String password) throws NoSuchUserException, AuthenticationException {
+        // Check if user in cache
+        if (!userCache.containsKey(email)) {
+            IRider rider = daoFactory.createRiderDAO().findByEmail(email);
+            if (rider == null)
+                throw new NoSuchUserException("Could not find user with email " + email);
+            userCache.put(email, rider.getPassword());
+        }
+        byte[] currentPassword = userCache.get(email);
+        byte[] newPassword = generateSHA1(password);
+
+        if (!Arrays.equals(currentPassword, newPassword)) {
+            throw new AuthenticationException("Failed to authenticate: Passwords do not match");
+        }
+        String token = UUID.randomUUID().toString();
+        tokenCache.put(token, email);
+        return token;
+    }
+
+    @PostConstruct
+    @Override
+    public void loadData() {
+        for (IRider rider : daoFactory.createRiderDAO().findAll()) {
+            userCache.putIfAbsent(rider.getEmail(), rider.getPassword());
+        }
+    }
+
+    @Override
+    public void clearCache() {
+        userCache.clear();
+    }
+
+    private byte[] generateSHA1(String string) {
+        MessageDigest digest;
+        try {
+            digest = MessageDigest.getInstance("SHA-1");
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+            throw new RuntimeException(e);
+        }
+        digest.update(string.getBytes());
+        return digest.digest();
+    }
+}