diff --git a/ass2-service/api/src/main/proto/dst/ass2/service/api/auth/proto/auth.proto b/ass2-service/api/src/main/proto/dst/ass2/service/api/auth/proto/auth.proto
index 2c92277..0929725 100644
--- a/ass2-service/api/src/main/proto/dst/ass2/service/api/auth/proto/auth.proto
+++ b/ass2-service/api/src/main/proto/dst/ass2/service/api/auth/proto/auth.proto
@@ -1,3 +1,29 @@
 syntax = "proto3";
 
-// TODO implement authentication service
+package dst.ass2.service.api.auth.proto;
+
+option java_package = "dst.ass2.service.api.auth.proto";
+option java_multiple_files = true;
+
+message AuthenticationRequest {
+  string email = 1;
+  string password = 2;
+}
+
+message AuthenticationResponse {
+  string token = 1;
+  string status = 2;
+}
+
+message TokenValidationRequest {
+  string token = 1;
+}
+
+message TokenValidationResponse {
+  bool valid = 1;
+}
+
+service AuthService {
+  rpc authenticate(AuthenticationRequest) returns (AuthenticationResponse);
+  rpc validateToken(TokenValidationRequest) returns (TokenValidationResponse);
+}
\ No newline at end of file
diff --git a/ass2-service/auth-client/src/main/java/dst/ass2/service/auth/client/impl/GrpcAuthenticationClient.java b/ass2-service/auth-client/src/main/java/dst/ass2/service/auth/client/impl/GrpcAuthenticationClient.java
index 3ae5082..b3559ea 100644
--- a/ass2-service/auth-client/src/main/java/dst/ass2/service/auth/client/impl/GrpcAuthenticationClient.java
+++ b/ass2-service/auth-client/src/main/java/dst/ass2/service/auth/client/impl/GrpcAuthenticationClient.java
@@ -2,31 +2,45 @@ package dst.ass2.service.auth.client.impl;
 
 import dst.ass2.service.api.auth.AuthenticationException;
 import dst.ass2.service.api.auth.NoSuchUserException;
+import dst.ass2.service.api.auth.proto.*;
 import dst.ass2.service.auth.client.AuthenticationClientProperties;
 import dst.ass2.service.auth.client.IAuthenticationClient;
+import io.grpc.ManagedChannel;
+import io.grpc.ManagedChannelBuilder;
+import io.grpc.StatusRuntimeException;
 
 public class GrpcAuthenticationClient implements IAuthenticationClient {
-
-    // TODO make use of the generated grpc sources to implement a blocking client
+    private final ManagedChannel channel;
+    private final AuthServiceGrpc.AuthServiceBlockingStub blockingStub;
 
     public GrpcAuthenticationClient(AuthenticationClientProperties properties) {
-        // TODO
+        this.channel = ManagedChannelBuilder.forAddress(properties.getHost(), properties.getPort()).usePlaintext().build();
+        this.blockingStub = AuthServiceGrpc.newBlockingStub(this.channel);
     }
 
     @Override
     public String authenticate(String email, String password) throws NoSuchUserException, AuthenticationException {
-        // TODO
-        return null;
+        AuthenticationRequest request = AuthenticationRequest.newBuilder().setEmail(email).setPassword(password).build();
+        AuthenticationResponse response = blockingStub.authenticate(request);
+
+        if(response.getStatus().startsWith("NoSuchUserException"))
+            throw new NoSuchUserException("User with email " + email + " could not be found");
+
+        if(response.getStatus().startsWith("AuthenticationException"))
+            throw new AuthenticationException("Password for user with email " + email + " was incorrect");
+
+        return response.getToken();
     }
 
     @Override
     public boolean isTokenValid(String token) {
-        // TODO
-        return false;
+        TokenValidationRequest request = TokenValidationRequest.newBuilder().setToken(token).build();
+        TokenValidationResponse response = blockingStub.validateToken(request);
+        return response.getValid();
     }
 
     @Override
     public void close() {
-        // TODO
+        this.channel.shutdownNow();
     }
 }
diff --git a/ass2-service/auth/src/main/java/dst/ass2/service/auth/impl/GrpcServerRunner.java b/ass2-service/auth/src/main/java/dst/ass2/service/auth/impl/GrpcServerRunner.java
new file mode 100644
index 0000000..891e12a
--- /dev/null
+++ b/ass2-service/auth/src/main/java/dst/ass2/service/auth/impl/GrpcServerRunner.java
@@ -0,0 +1,61 @@
+package dst.ass2.service.auth.impl;
+
+import dst.ass2.service.api.auth.AuthenticationException;
+import dst.ass2.service.api.auth.IAuthenticationService;
+import dst.ass2.service.api.auth.NoSuchUserException;
+import dst.ass2.service.api.auth.proto.*;
+import dst.ass2.service.auth.grpc.GrpcServerProperties;
+import dst.ass2.service.auth.grpc.IGrpcServerRunner;
+import io.grpc.Server;
+import io.grpc.ServerBuilder;
+import io.grpc.stub.StreamObserver;
+
+import javax.annotation.Resource;
+import javax.inject.Named;
+import javax.inject.Singleton;
+import java.io.IOException;
+
+@Named
+@Singleton
+public class GrpcServerRunner extends AuthServiceGrpc.AuthServiceImplBase implements IGrpcServerRunner {
+    @Resource
+    private GrpcServerProperties properties;
+    @Resource
+    private IAuthenticationService authenticationService;
+
+    @Override
+    public void run() throws IOException {
+        int port = properties.getPort();
+        Server server = ServerBuilder.forPort(port)
+                .addService(bindService())
+                .build()
+                .start();
+    }
+
+    @Override
+    public void authenticate(AuthenticationRequest request, StreamObserver<AuthenticationResponse> responseObserver) {
+        AuthenticationResponse response;
+        try {
+            String token = authenticationService.authenticate(request.getEmail(), request.getPassword());
+            response = AuthenticationResponse.newBuilder().setToken(token).build();
+        } catch (NoSuchUserException e){
+            response = AuthenticationResponse.newBuilder().setStatus("NoSuchUserException").build();
+        } catch (AuthenticationException e) {
+            response = AuthenticationResponse.newBuilder().setStatus("AuthenticationException").build();
+        }
+
+        responseObserver.onNext(response);
+        responseObserver.onCompleted();
+    }
+
+    @Override
+    public void validateToken(TokenValidationRequest request, StreamObserver<TokenValidationResponse> responseObserver) {
+        TokenValidationResponse response = TokenValidationResponse.newBuilder().setValid(false).build();
+
+        if(authenticationService.isValid(request.getToken()))
+            response = TokenValidationResponse.newBuilder().setValid(true).build();
+
+        responseObserver.onNext(response);
+        responseObserver.onCompleted();
+    }
+}