diff --git a/pom.xml b/pom.xml
index b55f960..daf68c6 100644
--- a/pom.xml
+++ b/pom.xml
@@ -24,10 +24,10 @@
 			<groupId>com.h2database</groupId>
 			<artifactId>h2</artifactId>
 		</dependency>
-		<!-- dependency>
+		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-security</artifactId>
-		</dependency -->
+		</dependency>
 	</dependencies>
 
 	<properties>
diff --git a/src/main/java/de/tilman/transactions/SecurityConfiguration.java b/src/main/java/de/tilman/transactions/SecurityConfiguration.java
new file mode 100644
index 0000000..689528d
--- /dev/null
+++ b/src/main/java/de/tilman/transactions/SecurityConfiguration.java
@@ -0,0 +1,34 @@
+package de.tilman.transactions;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
+import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
+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.WebSecurityConfigurerAdapter;
+
+@Configuration
+@EnableGlobalMethodSecurity(prePostEnabled = true)
+@EnableWebSecurity
+public class SecurityConfiguration extends WebSecurityConfigurerAdapter {
+
+	@Override
+	protected void configure(AuthenticationManagerBuilder auth) throws Exception {
+		auth.inMemoryAuthentication()
+			.withUser("Adam").password("test").roles("USER", "ADMIN").and()
+			.withUser("Betty").password("test").roles("USER");
+	}
+
+	@Override
+	protected void configure(HttpSecurity http) throws Exception {
+		// Basis-Schutz: Nur autorisierte Zugriffe (feingranulare Steuerung über Assertions)
+		http.authorizeRequests()
+			//.antMatchers(HttpMethod.GET, "/public/**").permitAll()
+			.anyRequest().authenticated();
+		
+		http.httpBasic();
+		//http.formLogin();
+		
+		http.csrf().disable();
+	}
+}
diff --git a/src/main/java/de/tilman/transactions/repository/AccountRepository.java b/src/main/java/de/tilman/transactions/repository/AccountRepository.java
index 1dbde79..2cf1250 100644
--- a/src/main/java/de/tilman/transactions/repository/AccountRepository.java
+++ b/src/main/java/de/tilman/transactions/repository/AccountRepository.java
@@ -1,8 +1,27 @@
 package de.tilman.transactions.repository;
 
+import java.util.List;
+
+import org.springframework.data.domain.Page;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.query.Param;
+import org.springframework.security.access.prepost.PreAuthorize;
 
 import de.tilman.transactions.domain.Account;
 
 public interface AccountRepository extends CrudRepository<Account, Long> {
+	
+	// http://localhost:8080/accounts/search/findByUserName?username=Betty
+	@Query("SELECT a FROM Account a INNER JOIN a.users u WHERE u.name = :username")
+	@PreAuthorize("isFullyAuthenticated() && (#username == principal.username)") // http://stackoverflow.com/q/23640487/3761783
+	//@PostFilter("filterObject.user.getId() == principal.id") // http://stackoverflow.com/a/30877376/3761783
+	List<Account> findByUserName(@Param("username") String username);
+	
+	// TODO DELETE auf fremde Accounts möglich?
+	
+	@PreAuthorize("hasRole('ROLE_ADMIN')")
+	@Override
+	Iterable<Account> findAll();
+
 }
diff --git a/src/main/java/de/tilman/transactions/repository/CategoryRepository.java b/src/main/java/de/tilman/transactions/repository/CategoryRepository.java
index 22161ea..932f08b 100644
--- a/src/main/java/de/tilman/transactions/repository/CategoryRepository.java
+++ b/src/main/java/de/tilman/transactions/repository/CategoryRepository.java
@@ -1,9 +1,31 @@
 package de.tilman.transactions.repository;
 
+import java.util.List;
+
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.repository.query.Param;
+import org.springframework.security.access.prepost.PreAuthorize;
 
 import de.tilman.transactions.domain.Category;
 
 public interface CategoryRepository extends PagingAndSortingRepository<Category, Long> {
+	
+	// TODO How to prevent users from retrieving/changing categories of other user's accounts? 
+	// http://localhost:8080/categories/search/findByAccountIdOrderByPositionAsc?accountId=1
+	List<Category> findByAccountIdOrderByPositionAsc(@Param("accountId") Long accountId);
+	
+	@PreAuthorize("hasRole('ROLE_ADMIN')")
+	@Override
+	Category save(Category user);
+
+	@PreAuthorize("hasRole('ROLE_ADMIN')")
+	@Override
+	void delete(Category user);
+	
+	@PreAuthorize("hasRole('ROLE_ADMIN')")
+	@Override
+	Page<Category> findAll(Pageable pageable);
 
 }
diff --git a/src/main/java/de/tilman/transactions/repository/TransactionRepository.java b/src/main/java/de/tilman/transactions/repository/TransactionRepository.java
index 8d8a687..390cb2d 100644
--- a/src/main/java/de/tilman/transactions/repository/TransactionRepository.java
+++ b/src/main/java/de/tilman/transactions/repository/TransactionRepository.java
@@ -1,9 +1,15 @@
 package de.tilman.transactions.repository;
 
+import org.springframework.data.domain.Page;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RestResource;
 
 import de.tilman.transactions.domain.Transaction;
 
 public interface TransactionRepository extends PagingAndSortingRepository<Transaction, Long> {
 
+	@RestResource(exported = false)
+	@Override
+	Page<Transaction> findAll();
+
 }
diff --git a/src/main/java/de/tilman/transactions/repository/UserRepository.java b/src/main/java/de/tilman/transactions/repository/UserRepository.java
index 07a26e8..82d06c6 100644
--- a/src/main/java/de/tilman/transactions/repository/UserRepository.java
+++ b/src/main/java/de/tilman/transactions/repository/UserRepository.java
@@ -1,13 +1,24 @@
 package de.tilman.transactions.repository;
 
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.security.access.prepost.PreAuthorize;
 
 import de.tilman.transactions.domain.User;
 
 public interface UserRepository extends PagingAndSortingRepository<User, Long> {
 	
-//	@Override
-//	@PreAuthorize("hasRole('ROLE_ADMIN')")
-//	public Page<User> findAll(Pageable pageable);
+	@PreAuthorize("hasRole('ROLE_ADMIN')")
+	@Override
+	User save(User user);
+
+	@PreAuthorize("hasRole('ROLE_ADMIN')")
+	@Override
+	void delete(User user);
+	
+	@Override
+	@PreAuthorize("hasRole('ROLE_ADMIN')")
+	public Page<User> findAll(Pageable pageable);
 	
 }
\ No newline at end of file
diff --git a/src/main/resources/data-h2.sql b/src/main/resources/data-h2.sql
index a1dbe46..68a8cad 100644
--- a/src/main/resources/data-h2.sql
+++ b/src/main/resources/data-h2.sql
@@ -1,11 +1,12 @@
-INSERT INTO User (id, name) VALUES (1, 'Tilman'), (2, 'Anica');
-INSERT INTO Account (id, name, owner_id) VALUES (1, 'Gemeinschaftskonto', 1), (2, 'Konto Tilman', 1);
+INSERT INTO User (id, name) VALUES (1, 'Adam'), (2, 'Betty');
+INSERT INTO Account (id, name, owner_id) VALUES (1, 'Gemeinschaftskonto', 1), (2, 'Konto Adam', 1);
 
 INSERT INTO Category (id, name, account_id, position) VALUES (1, 'Essen - Lebensmittel', 1, 2), (2, 'Einnahmen - Gehalt', 1, 1), (3, 'Essen - Arbeit', 1, 3), (4, 'Einnahmen - Gehalt', 2, 1), (5, 'Technik - Server und Hosting', 2, 2);
 
 
 INSERT INTO Account_User (account_id, user_id) VALUES (1, 1), (1, 2), (2, 1);
 
+/*
 INSERT INTO Transaction (id, amount, account_id, category_id, date, description, creditor_id) VALUES
  (NULL, 1280.81, 1, 1, '2014-06-01', 'Gehalt', null),
  (NULL, -2.21, 1, 2, '2014-06-10', 'Brot', null),
@@ -16,10 +17,10 @@ INSERT INTO Transaction (id, amount, account_id, category_id, date, description,
  (NULL, -4.50, 1, 3, '2014-06-20', 'Currywurst', null),
  (NULL, -4.50, 2, 3, '2014-06-20', 'Currywurst', null),
  (NULL, -4.09, 1, 3, '2014-06-18', 'Currywurst-Frühstück', null),
- (NULL, -4.90, 1, 3, '2014-06-18', 'Currywurst (Auslage Anica)', 2),
- (NULL, -8.90, 1, 3, '2014-06-18', 'Curry beim Inder (Auslage Tilman)', 1),
+ (NULL, -4.90, 1, 3, '2014-06-18', 'Currywurst (Auslage Betty)', 2),
+ (NULL, -8.90, 1, 3, '2014-06-18', 'Curry beim Inder (Auslage Adam)', 1),
  (NULL, -12.00, 2, 3, '2014-06-18', 'Curry Thai', null),
- (NULL, 1340.22, 2, 4, '2014-06-02', 'Gehalt Tilman', null),
+ (NULL, 1340.22, 2, 4, '2014-06-02', 'Gehalt Adam', null),
  (NULL, -12.90, 2, 5, '2014-06-16', 'Host Europe', null);
 
 
@@ -27,3 +28,4 @@ INSERT INTO Transaction (id, amount, account_id, category_id, date, description,
 INSERT INTO Transaction (id, amount, account_id, category_id, date, description, creditor_id) VALUES (NULL, -1.50, 1, 2, CURRENT_TIMESTAMP(), 'Transaction', null); Commit;
 INSERT INTO Transaction (id, amount, account_id, category_id, date, description, creditor_id) VALUES (NULL, -1.50, 1, 3, CURRENT_TIMESTAMP(), 'Transaction', null); Commit;
 INSERT INTO Transaction (id, amount, account_id, category_id, date, description, creditor_id) VALUES (NULL, 1.50, 1, 4, CURRENT_TIMESTAMP()+1, 'LAST Transaction', null); Commit;
+*/
\ No newline at end of file