ActivityPub: HTTP Signatures and autoaccept followers

22 files changed, 375 insertions, 118 deletions

diff --git a/juick-server/src/main/java/com/juick/server/ActivityPubManager.java b/juick-server/src/main/java/com/juick/server/ActivityPubManager.java
new file mode 100644
index 00000000..362754fd
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/ActivityPubManager.java
@@ -0,0 +1,37 @@
+package com.juick.server;
+
+import com.juick.server.api.activity.model.Person;
+import com.juick.server.api.activity.model.activities.Accept;
+import com.juick.service.activities.FollowEvent;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.context.ApplicationListener;
+import org.springframework.stereotype.Component;
+
+import javax.annotation.Nonnull;
+import javax.inject.Inject;
+import java.io.IOException;
+import java.net.URI;
+
+@Component
+public class ActivityPubManager implements ApplicationListener<FollowEvent> {
+    private static final Logger logger = LoggerFactory.getLogger(ActivityPubManager.class);
+    @Inject
+    SignatureManager signatureManager;
+    @Override
+    public void onApplicationEvent(@Nonnull FollowEvent followEvent) {
+        logger.info("received follower request");
+        // automatically accept follower requests
+        Person me = (Person) signatureManager.getContext(URI.create((String)followEvent.getRequest().getObject()));
+        Person follower = (Person) signatureManager.getContext(URI.create(followEvent.getRequest().getActor()));
+        Accept accept = new Accept();
+        accept.setActor(me.getId());
+        accept.setObject(followEvent.getRequest());
+        try {
+            signatureManager.post(me, follower, accept);
+        } catch (IOException e) {
+            logger.info("activitypub exception", e);
+        }
+
+    }
+}
diff --git a/juick-server/src/main/java/com/juick/server/KeystoreManager.java b/juick-server/src/main/java/com/juick/server/KeystoreManager.java
index 75d72e72..855052c4 100644
--- a/juick-server/src/main/java/com/juick/server/KeystoreManager.java
+++ b/juick-server/src/main/java/com/juick/server/KeystoreManager.java
@@ -1,5 +1,6 @@
 package com.juick.server;
 
+import com.juick.server.api.activity.model.Person;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Value;
@@ -14,8 +15,11 @@ import java.io.InputStream;
 import java.security.*;
 import java.security.cert.Certificate;
 import java.security.cert.CertificateException;
+import java.security.spec.X509EncodedKeySpec;
 import java.util.Arrays;
+import java.util.List;
 import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 
 @Component
 public class KeystoreManager {
@@ -61,9 +65,30 @@ public class KeystoreManager {
         }
         return null;
     }
-    public String getPublicKey() {
+    public PrivateKey getPrivateKey() {
+        return getKeyPair().getPrivate();
+    }
+    public PublicKey getPublicKey() {
+        return getKeyPair().getPublic();
+    }
+    public String getPublicKeyPem() {
         String[] key = Base64Utils.encodeToString(getKeyPair().getPublic().getEncoded()).split("(?<=\\G.{64})");
         return String.format("-----BEGIN PUBLIC KEY-----\n%s\n-----END PUBLIC KEY-----\n",
                 Arrays.asList(key).stream().collect(Collectors.joining("\n")));
     }
+    public static PublicKey publicKeyOf(Person person) {
+        String pubkeyPem = person.getPublicKey().getPublicKeyPem();
+        String[] rawKey = pubkeyPem.split("\\n");
+        String pubkeyData = String.join("", Arrays.asList(rawKey).subList(1, rawKey.length - 1));
+        try{
+            byte[] byteKey = Base64Utils.decodeFromString(pubkeyData);
+            X509EncodedKeySpec X509publicKey = new X509EncodedKeySpec(byteKey);
+            KeyFactory kf = KeyFactory.getInstance("RSA");
+            return kf.generatePublic(X509publicKey);
+        }
+        catch(Exception e){
+            e.printStackTrace();
+        }
+        return null;
+    }
 }
diff --git a/juick-server/src/main/java/com/juick/server/SignatureManager.java b/juick-server/src/main/java/com/juick/server/SignatureManager.java
new file mode 100644
index 00000000..d89919f0
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/SignatureManager.java
@@ -0,0 +1,79 @@
+package com.juick.server;
+
+import com.juick.server.api.activity.model.Context;
+import com.juick.server.api.activity.model.Person;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Component;
+import org.springframework.web.client.RestTemplate;
+import org.springframework.web.util.UriComponentsBuilder;
+import org.tomitribe.auth.signatures.Signature;
+import org.tomitribe.auth.signatures.Signer;
+import org.tomitribe.auth.signatures.Verifier;
+
+import javax.inject.Inject;
+import java.io.IOException;
+import java.net.URI;
+import java.security.Key;
+import java.security.NoSuchAlgorithmException;
+import java.security.SignatureException;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.util.HashMap;
+import java.util.Map;
+
+@Component
+public class SignatureManager {
+    private static final Logger logger = LoggerFactory.getLogger(ActivityPubManager.class);
+    @Inject
+    private KeystoreManager keystoreManager;
+
+    public void post(Person from, Person to, Context data) throws IOException {
+        UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(to.getInbox());
+        URI inbox = uriComponentsBuilder.build().toUri();
+        Instant now = Instant.now();
+        String requestDate = DateTimeFormatter.RFC_1123_DATE_TIME.withZone(ZoneId.of("UTC")).format(now);
+        Signature templateSignature = new Signature(from.getPublicKey().getId(), "rsa-sha256", null,
+                "(request-target)", "host", "date");
+        Signer signer = new Signer(keystoreManager.getPrivateKey(), templateSignature);
+        Map<String, String> headers = new HashMap<>();
+        headers.put("host", inbox.getHost());
+        headers.put("date", requestDate);
+        Signature signature = signer.sign("POST", inbox.getPath(), headers);
+        HttpHeaders requestHeaders = new HttpHeaders();
+        requestHeaders.add("Content-Type", Context.ACTIVITY_JSON_MEDIA_TYPE);
+        requestHeaders.add("Date", requestDate);
+        requestHeaders.add("Signature", signature.toString().substring(10));
+        HttpEntity<Context> request = new HttpEntity<>(Context.build(data), requestHeaders);
+        //boolean valid = verifySignature(Signature.fromString(requestHeaders.getFirst("Signature")),
+          //      keystoreManager.getPublicKey(), "POST", inbox.getPath(), headers);
+        ResponseEntity<Void> response = new RestTemplate().postForEntity(inbox, request, Void.class);
+        logger.info("accepted follower: {}", response.getStatusCode().is2xxSuccessful());
+    }
+    public boolean verifySignature(String signatureString, URI actor, String method, String path, Map<String, String> headers) {
+        Context context = getContext(actor);
+        if (context instanceof Person) {
+            Person person = (Person) context;
+            Key key = KeystoreManager.publicKeyOf(person);
+            logger.info("data signed by person with key {}", key);
+            Verifier verifier = new Verifier(key, Signature.fromString(signatureString));
+            try {
+                boolean result = verifier.verify(method, path, headers);
+                logger.info("signature is valid: {}", result);
+                return result;
+            } catch (NoSuchAlgorithmException | SignatureException | IOException e) {
+                logger.info("signature exception", e);
+                return false;
+            }
+        }
+        logger.info("person not found");
+        return false;
+    }
+    public Context getContext(URI contextUri) {
+        return new RestTemplate().getForEntity(contextUri, Context.class).getBody();
+    }
+}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/Profile.java b/juick-server/src/main/java/com/juick/server/api/activity/Profile.java
index 9f98b4ea..656d85dd 100644
--- a/juick-server/src/main/java/com/juick/server/api/activity/Profile.java
+++ b/juick-server/src/main/java/com/juick/server/api/activity/Profile.java
@@ -2,24 +2,33 @@ package com.juick.server.api.activity;
 
 import com.juick.User;
 import com.juick.server.KeystoreManager;
+import com.juick.server.SignatureManager;
 import com.juick.server.api.activity.model.*;
+import com.juick.server.api.activity.model.activities.Create;
+import com.juick.server.api.activity.model.activities.Follow;
+import com.juick.server.api.activity.model.activities.Undo;
 import com.juick.server.util.HttpNotFoundException;
 import com.juick.server.util.UserUtils;
 import com.juick.service.MessagesService;
 import com.juick.service.UserService;
+import com.juick.service.activities.FollowEvent;
 import com.juick.util.MessageUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.springframework.beans.factory.annotation.Value;
-import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.PathVariable;
-import org.springframework.web.bind.annotation.RequestParam;
-import org.springframework.web.bind.annotation.RestController;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
 import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
+import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;
 
 import javax.inject.Inject;
+import java.net.URI;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -31,6 +40,10 @@ public class Profile {
     private MessagesService messagesService;
     @Inject
     private KeystoreManager keystoreManager;
+    @Inject
+    private SignatureManager signatureManager;
+    @Inject
+    private ApplicationEventPublisher applicationEventPublisher;
     @Value("${web_domain:localhost}")
     private String domain;
     @Value("${ap_base_uri:http://localhost:8080/}")
@@ -38,7 +51,7 @@ public class Profile {
     @Value("${img_url:http://localhost:8080/i/}")
     private String baseImagesUri;
 
-    @GetMapping(value = "/u/{userName}", produces = { ActivityObject.LD_JSON_MEDIA_TYPE, ActivityObject.ACTIVITY_JSON_MEDIA_TYPE })
+    @GetMapping(value = "/u/{userName}", produces = { Context.LD_JSON_MEDIA_TYPE, Context.ACTIVITY_JSON_MEDIA_TYPE })
     public Person getUser(@PathVariable String userName) {
         User user = userService.getUserByName(userName);
         if (!user.isAnonymous()) {
@@ -52,9 +65,9 @@ public class Profile {
             Key publicKey = new Key();
             publicKey.setId(person.getId() + "#main-key");
             publicKey.setOwner(person.getId());
-            publicKey.setPublicKeyPem(keystoreManager.getPublicKey());
+            publicKey.setPublicKeyPem(keystoreManager.getPublicKeyPem());
             person.setPublicKey(publicKey);
-            uri.replacePath("/post");
+            uri.replacePath("/api/inbox");
             person.setInbox(uri.toUriString());
             person.setOutbox(uri.replacePath(String.format("/u/%s/blog/toc", userName)).toUriString());
             person.setFollowers(uri.replacePath(String.format("/u/%s/followers/toc", userName)).toUriString());
@@ -65,11 +78,11 @@ public class Profile {
             avatar.setUrl(image.toUriString());
             avatar.setMediaType("image/png");
             person.setIcon(avatar);
-            return (Person) ActivityObject.build(person);
+            return (Person) Context.build(person);
         }
         throw new HttpNotFoundException();
     }
-    @GetMapping(value = "/u/{userName}/blog/toc", produces = { ActivityObject.LD_JSON_MEDIA_TYPE, ActivityObject.ACTIVITY_JSON_MEDIA_TYPE })
+    @GetMapping(value = "/u/{userName}/blog/toc", produces = { Context.LD_JSON_MEDIA_TYPE, Context.ACTIVITY_JSON_MEDIA_TYPE })
     public OrderedCollection getOutbox(@PathVariable String userName) {
         User user = userService.getUserByName(userName);
         if (!user.isAnonymous()) {
@@ -78,11 +91,11 @@ public class Profile {
             blog.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
             blog.setTotalItems(userService.getStatsMessages(user.getUid()));
             blog.setFirst(uriComponentsBuilder.path(String.format("/u/%s/blog", userName)).toUriString());
-            return (OrderedCollection) ActivityObject.build(blog);
+            return (OrderedCollection) Context.build(blog);
         }
         throw new HttpNotFoundException();
     }
-    @GetMapping(value = "/u/{userName}/blog", produces = { ActivityObject.LD_JSON_MEDIA_TYPE, ActivityObject.ACTIVITY_JSON_MEDIA_TYPE })
+    @GetMapping(value = "/u/{userName}/blog", produces = { Context.LD_JSON_MEDIA_TYPE, Context.ACTIVITY_JSON_MEDIA_TYPE })
     public OrderedCollectionPage getOutboxPage(@PathVariable String userName,
                                            @RequestParam(required = false, defaultValue = "0") int before) {
         User visitor = UserUtils.getCurrentUser();
@@ -127,11 +140,11 @@ public class Profile {
                 page.setNext(uri.queryParam("before", beforeNext).toUriString());
             }
             page.setLast(uri.replaceQueryParam("before", "1").toUriString());
-            return (OrderedCollectionPage) ActivityObject.build(page);
+            return (OrderedCollectionPage) Context.build(page);
         }
         throw new HttpNotFoundException();
     }
-    @GetMapping(value = "/u/{userName}/followers/toc", produces = { ActivityObject.LD_JSON_MEDIA_TYPE, ActivityObject.ACTIVITY_JSON_MEDIA_TYPE })
+    @GetMapping(value = "/u/{userName}/followers/toc", produces = { Context.LD_JSON_MEDIA_TYPE, Context.ACTIVITY_JSON_MEDIA_TYPE })
     public OrderedCollection getFollowers(@PathVariable String userName) {
         User user = userService.getUserByName(userName);
         if (!user.isAnonymous()) {
@@ -140,11 +153,11 @@ public class Profile {
             followers.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
             followers.setTotalItems(userService.getStatsMyReaders(user.getUid()));
             followers.setFirst(uriComponentsBuilder.path(String.format("/u/%s/followers", userName)).toUriString());
-            return (OrderedCollection) ActivityObject.build(followers);
+            return (OrderedCollection) Context.build(followers);
         }
         throw new HttpNotFoundException();
     }
-    @GetMapping(value = "/u/{userName}/followers", produces = { ActivityObject.LD_JSON_MEDIA_TYPE, ActivityObject.ACTIVITY_JSON_MEDIA_TYPE })
+    @GetMapping(value = "/u/{userName}/followers", produces = { Context.LD_JSON_MEDIA_TYPE, Context.ACTIVITY_JSON_MEDIA_TYPE })
     public OrderedCollectionPage getFollowersPage(@PathVariable String userName,
                                                @RequestParam(required = false, defaultValue = "0") int page) {
         User user = userService.getUserByName(userName);
@@ -169,11 +182,11 @@ public class Profile {
             if (hasNext) {
                 result.setNext(uriComponentsBuilder.queryParam("page", page + 1).toUriString());
             }
-            return (OrderedCollectionPage) ActivityObject.build(result);
+            return (OrderedCollectionPage) Context.build(result);
         }
         throw new HttpNotFoundException();
     }
-    @GetMapping(value = "/u/{userName}/following/toc", produces = { ActivityObject.LD_JSON_MEDIA_TYPE, ActivityObject.ACTIVITY_JSON_MEDIA_TYPE })
+    @GetMapping(value = "/u/{userName}/following/toc", produces = { Context.LD_JSON_MEDIA_TYPE, Context.ACTIVITY_JSON_MEDIA_TYPE })
     public OrderedCollection getFollowing(@PathVariable String userName) {
         User user = userService.getUserByName(userName);
         if (!user.isAnonymous()) {
@@ -182,11 +195,11 @@ public class Profile {
             following.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
             following.setTotalItems(userService.getUserFriends(user.getUid()).size());
             following.setFirst(uriComponentsBuilder.path(String.format("/u/%s/followers", userName)).toUriString());
-            return (OrderedCollection) ActivityObject.build(following);
+            return (OrderedCollection) Context.build(following);
         }
         throw new HttpNotFoundException();
     }
-    @GetMapping(value = "/u/{userName}/following", produces = { ActivityObject.LD_JSON_MEDIA_TYPE, ActivityObject.ACTIVITY_JSON_MEDIA_TYPE })
+    @GetMapping(value = "/u/{userName}/following", produces = { Context.LD_JSON_MEDIA_TYPE, Context.ACTIVITY_JSON_MEDIA_TYPE })
     public OrderedCollectionPage getFollowingPage(@PathVariable String userName,
                                                   @RequestParam(required = false, defaultValue = "0") int page) {
         User user = userService.getUserByName(userName);
@@ -211,8 +224,37 @@ public class Profile {
             if (hasNext) {
                 result.setNext(uriComponentsBuilder.queryParam("page", page + 1).toUriString());
             }
-            return (OrderedCollectionPage) ActivityObject.build(result);
+            return (OrderedCollectionPage) Context.build(result);
         }
         throw new HttpNotFoundException();
     }
+    @PostMapping(value = "/api/inbox", consumes = { Context.LD_JSON_MEDIA_TYPE, Context.ACTIVITY_JSON_MEDIA_TYPE })
+    public ResponseEntity<Void> processInbox(@RequestBody Context activity,
+                                             @RequestHeader(name = "Host") String host,
+                                             @RequestHeader(name = "Date") String date,
+                                             @RequestHeader(name = "Digest") String digest,
+                                             @RequestHeader(name = "Content-Type") String contentType,
+                                             @RequestHeader(name = "Signature") String signature) {
+        if (activity instanceof Follow) {
+            Follow followRequest = (Follow) activity;
+            UriComponents componentsBuilder = ServletUriComponentsBuilder.fromCurrentRequestUri().build();
+            Map<String, String> headers = new HashMap<>();
+            headers.put("host", host);
+            headers.put("date", date);
+            headers.put("digest", digest);
+            headers.put("content-type", contentType);
+            boolean valid = signatureManager.verifySignature(signature, URI.create(followRequest.getActor()), "POST",
+                    componentsBuilder.getPath(), headers);
+            if (valid) {
+                applicationEventPublisher.publishEvent(
+                        new FollowEvent(this, followRequest));
+                return new ResponseEntity<>(HttpStatus.ACCEPTED);
+            }
+            return new ResponseEntity<>(HttpStatus.UNAUTHORIZED);
+        }
+        if (activity instanceof Undo) {
+            return new ResponseEntity<>(HttpStatus.OK);
+        }
+        return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
+    }
 }
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/Activity.java b/juick-server/src/main/java/com/juick/server/api/activity/model/Activity.java
new file mode 100644
index 00000000..ec126b88
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/Activity.java
@@ -0,0 +1,23 @@
+package com.juick.server.api.activity.model;
+
+public abstract class Activity extends Context {
+
+    private String actor;
+    private Object object;
+
+    public String getActor() {
+        return actor;
+    }
+
+    public void setActor(String actor) {
+        this.actor = actor;
+    }
+
+    public Object getObject() {
+        return object;
+    }
+
+    public void setObject(Object object) {
+        this.object = object;
+    }
+}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/ActivityObject.java b/juick-server/src/main/java/com/juick/server/api/activity/model/ActivityObject.java
deleted file mode 100644
index fceb3612..00000000
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/ActivityObject.java
+++ /dev/null
@@ -1,52 +0,0 @@
-package com.juick.server.api.activity.model;
-
-import com.fasterxml.jackson.annotation.JsonProperty;
-
-import java.time.Instant;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-
-public abstract class ActivityObject {
-
-    private List<String> context;
-
-    private String id;
-
-    private Instant published;
-
-    public String getId() {
-        return id;
-    }
-
-    public void setId(String id) {
-        this.id = id;
-    }
-
-    public String getType() {
-        return getClass().getSimpleName();
-    }
-
-    @JsonProperty("@context")
-    public List<String> getContext() {
-        return context;
-    }
-
-    public final static String ACTIVITY_STREAMS_URI = "https://www.w3.org/ns/activitystreams";
-    public final static String SECURITY_URI = "https://w3id.org/security/v1";
-    public final static String LD_JSON_MEDIA_TYPE = "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\"";
-    public final static String ACTIVITY_JSON_MEDIA_TYPE = "application/activity+json; profile=\"https://www.w3.org/ns/activitystreams\"";
-
-    public Instant getPublished() {
-        return published;
-    }
-
-    public void setPublished(Instant published) {
-        this.published = published;
-    }
-
-    public static ActivityObject build(ActivityObject response) {
-        response.context = Arrays.asList(ACTIVITY_STREAMS_URI, SECURITY_URI);
-        return response;
-    }
-}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/Context.java b/juick-server/src/main/java/com/juick/server/api/activity/model/Context.java
new file mode 100644
index 00000000..984eb2cd
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/Context.java
@@ -0,0 +1,82 @@
+package com.juick.server.api.activity.model;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.juick.server.api.activity.model.activities.*;
+
+import java.time.Instant;
+import java.util.Arrays;
+import java.util.List;
+
+@JsonIgnoreProperties(ignoreUnknown = true)
+@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property="type")
+@JsonSubTypes({
+        @JsonSubTypes.Type(value = Create.class, name = "Create"),
+        @JsonSubTypes.Type(value = Delete.class, name = "Delete"),
+        @JsonSubTypes.Type(value = Follow.class, name = "Follow"),
+        @JsonSubTypes.Type(value = Accept.class, name = "Accept"),
+        @JsonSubTypes.Type(value = Undo.class, name = "Undo"),
+        @JsonSubTypes.Type(value = Image.class, name = "Image"),
+        @JsonSubTypes.Type(value = Key.class, name = "Key"),
+        @JsonSubTypes.Type(value = Link.class, name = "Link"),
+        @JsonSubTypes.Type(value = Note.class, name = "Note"),
+        @JsonSubTypes.Type(value = OrderedCollection.class, name = "OrderedCollection"),
+        @JsonSubTypes.Type(value = OrderedCollectionPage.class, name = "OrderedCollectionPage"),
+        @JsonSubTypes.Type(value = Person.class, name = "Person")
+})
+public abstract class Context {
+
+    private List<Object> context;
+
+    private String id;
+
+    private Instant published;
+
+
+    private List<String> to;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getType() {
+        return getClass().getSimpleName();
+    }
+
+    @JsonProperty("@context")
+    public List<Object> getContext() {
+        return context;
+    }
+
+    public final static String ACTIVITY_STREAMS_URI = "https://www.w3.org/ns/activitystreams";
+    public final static String SECURITY_URI = "https://w3id.org/security/v1";
+    public final static String LD_JSON_MEDIA_TYPE = "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\"";
+    public final static String ACTIVITY_JSON_MEDIA_TYPE = "application/activity+json; profile=\"https://www.w3.org/ns/activitystreams\"";
+
+    public Instant getPublished() {
+        return published;
+    }
+
+    public void setPublished(Instant published) {
+        this.published = published;
+    }
+
+    public List<String> getTo() {
+        return to;
+    }
+
+    public void setTo(List<String> to) {
+        this.to = to;
+    }
+
+    public static Context build(Context response) {
+        response.context = Arrays.asList(ACTIVITY_STREAMS_URI, SECURITY_URI);
+        return response;
+    }
+}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/Create.java b/juick-server/src/main/java/com/juick/server/api/activity/model/Create.java
deleted file mode 100644
index 2acdd6a6..00000000
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/Create.java
+++ /dev/null
@@ -1,34 +0,0 @@
-package com.juick.server.api.activity.model;
-
-import java.util.List;
-
-public class Create extends ActivityObject {
-
-    private String actor;
-    private Note object;
-    private List<String> to;
-
-    public String getActor() {
-        return actor;
-    }
-
-    public void setActor(String actor) {
-        this.actor = actor;
-    }
-
-    public Note getObject() {
-        return object;
-    }
-
-    public void setObject(Note object) {
-        this.object = object;
-    }
-
-    public List<String> getTo() {
-        return to;
-    }
-
-    public void setTo(List<String> to) {
-        this.to = to;
-    }
-}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/Image.java b/juick-server/src/main/java/com/juick/server/api/activity/model/Image.java
index 9a3b1659..c8f869a5 100644
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/Image.java
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/Image.java
@@ -1,6 +1,6 @@
 package com.juick.server.api.activity.model;
 
-public class Image extends ActivityObject {
+public class Image extends Context {
     private String mediaType;
     private String url;
 
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/Key.java b/juick-server/src/main/java/com/juick/server/api/activity/model/Key.java
index 32417778..bc41b460 100644
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/Key.java
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/Key.java
@@ -1,6 +1,6 @@
 package com.juick.server.api.activity.model;
 
-public class Key extends ActivityObject {
+public class Key extends Context {
     private String owner;
     private String publicKeyPem;
 
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/Link.java b/juick-server/src/main/java/com/juick/server/api/activity/model/Link.java
index b57dabbe..543b5f0c 100644
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/Link.java
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/Link.java
@@ -1,6 +1,6 @@
 package com.juick.server.api.activity.model;
 
-public class Link extends ActivityObject {
+public class Link extends Context {
     private String href;
 
     public String getHref() {
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/Note.java b/juick-server/src/main/java/com/juick/server/api/activity/model/Note.java
index ac58b033..ff64c4b9 100644
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/Note.java
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/Note.java
@@ -2,7 +2,7 @@ package com.juick.server.api.activity.model;
 
 import java.util.List;
 
-public class Note extends ActivityObject {
+public class Note extends Context {
     private String content;
     private String attributedTo;
     private Link attachment;
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/OrderedCollection.java b/juick-server/src/main/java/com/juick/server/api/activity/model/OrderedCollection.java
index 90f04de3..d66c55be 100644
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/OrderedCollection.java
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/OrderedCollection.java
@@ -1,6 +1,6 @@
 package com.juick.server.api.activity.model;
 
-public class OrderedCollection extends ActivityObject {
+public class OrderedCollection extends Context {
 
     private int totalItems;
 
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/OrderedCollectionPage.java b/juick-server/src/main/java/com/juick/server/api/activity/model/OrderedCollectionPage.java
index af7f2cec..bcae87d0 100644
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/OrderedCollectionPage.java
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/OrderedCollectionPage.java
@@ -2,7 +2,7 @@ package com.juick.server.api.activity.model;
 
 import java.util.List;
 
-public class OrderedCollectionPage extends ActivityObject {
+public class OrderedCollectionPage extends Context {
 
     private String partOf;
 
@@ -12,7 +12,7 @@ public class OrderedCollectionPage extends ActivityObject {
 
     private String last;
 
-    private List<? extends ActivityObject> orderedItems;
+    private List<? extends Context> orderedItems;
 
     public String getNext() {
         return next;
@@ -22,11 +22,11 @@ public class OrderedCollectionPage extends ActivityObject {
         this.next = next;
     }
 
-    public List<? extends ActivityObject> getOrderedItems() {
+    public List<? extends Context> getOrderedItems() {
         return orderedItems;
     }
 
-    public void setOrderedItems(List<? extends ActivityObject> orderedItems) {
+    public void setOrderedItems(List<? extends Context> orderedItems) {
         this.orderedItems = orderedItems;
     }
 
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/Person.java b/juick-server/src/main/java/com/juick/server/api/activity/model/Person.java
index e314624d..8a817c18 100644
--- a/juick-server/src/main/java/com/juick/server/api/activity/model/Person.java
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/Person.java
@@ -1,6 +1,8 @@
 package com.juick.server.api.activity.model;
 
-public class Person extends ActivityObject {
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+
+public class Person extends Context {
 
     private String name;
     private String preferredUsername;
@@ -25,6 +27,7 @@ public class Person extends ActivityObject {
         this.name = name;
     }
 
+    @JsonTypeInfo(use = JsonTypeInfo.Id.NONE)
     public Image getIcon() {
         return icon;
     }
@@ -73,6 +76,7 @@ public class Person extends ActivityObject {
         this.url = url;
     }
 
+    @JsonTypeInfo(use = JsonTypeInfo.Id.NONE)
     public Key getPublicKey() {
         return publicKey;
     }
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Accept.java b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Accept.java
new file mode 100644
index 00000000..1e0a9968
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Accept.java
@@ -0,0 +1,6 @@
+package com.juick.server.api.activity.model.activities;
+
+import com.juick.server.api.activity.model.Activity;
+
+public class Accept extends Activity {
+}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Create.java b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Create.java
new file mode 100644
index 00000000..52507373
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Create.java
@@ -0,0 +1,6 @@
+package com.juick.server.api.activity.model.activities;
+
+import com.juick.server.api.activity.model.Activity;
+
+public class Create extends Activity {
+}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Delete.java b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Delete.java
new file mode 100644
index 00000000..f4392020
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Delete.java
@@ -0,0 +1,6 @@
+package com.juick.server.api.activity.model.activities;
+
+import com.juick.server.api.activity.model.Activity;
+
+public class Delete extends Activity {
+}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Follow.java b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Follow.java
new file mode 100644
index 00000000..573ecc6e
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Follow.java
@@ -0,0 +1,6 @@
+package com.juick.server.api.activity.model.activities;
+
+import com.juick.server.api.activity.model.Activity;
+
+public class Follow extends Activity {
+}
diff --git a/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Undo.java b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Undo.java
new file mode 100644
index 00000000..4e87e9d0
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/server/api/activity/model/activities/Undo.java
@@ -0,0 +1,6 @@
+package com.juick.server.api.activity.model.activities;
+
+import com.juick.server.api.activity.model.Activity;
+
+public class Undo extends Activity {
+}
diff --git a/juick-server/src/main/java/com/juick/server/configuration/SecurityConfig.java b/juick-server/src/main/java/com/juick/server/configuration/SecurityConfig.java
index 23e2a4e6c..9ce8621e 100644
--- a/juick-server/src/main/java/com/juick/server/configuration/SecurityConfig.java
+++ b/juick-server/src/main/java/com/juick/server/configuration/SecurityConfig.java
@@ -97,7 +97,7 @@ public class SecurityConfig {
                     .authorizeRequests()
                     .antMatchers(HttpMethod.OPTIONS).permitAll()
                     .antMatchers("/api/", "/api/messages", "/api/messages/discussions", "/api/users", "/api/thread", "/api/tags", "/api/tlgmbtwbhk", "/api/fbwbhk",
-                            "/api/skypebotendpoint", "/api/_fblogin", "/api/_vklogin", "/api/_tglogin", "/api/u/**", "/.well-known/webfinger", "/rss/**").permitAll()
+                            "/api/skypebotendpoint", "/api/_fblogin", "/api/_vklogin", "/api/_tglogin", "/api/inbox", "/api/u/**", "/.well-known/webfinger", "/rss/**").permitAll()
                     .anyRequest().hasRole("USER")
                     .and()
                     .anonymous().principal(JuickUser.ANONYMOUS_USER).authorities(JuickUser.ANONYMOUS_AUTHORITY)
diff --git a/juick-server/src/main/java/com/juick/service/activities/FollowEvent.java b/juick-server/src/main/java/com/juick/service/activities/FollowEvent.java
new file mode 100644
index 00000000..c96613ba
--- /dev/null
+++ b/juick-server/src/main/java/com/juick/service/activities/FollowEvent.java
@@ -0,0 +1,21 @@
+package com.juick.service.activities;
+
+import com.juick.server.api.activity.model.activities.Follow;
+import org.springframework.context.ApplicationEvent;
+
+public class FollowEvent extends ApplicationEvent {
+    private Follow request;
+    /**
+     * Create a new ApplicationEvent.
+     *
+     * @param source the object on which the event initially occurred (never {@code null})
+     */
+    public FollowEvent(Object source, Follow followRequest) {
+        super(source);
+        this.request = followRequest;
+    }
+
+    public Follow getRequest() {
+        return request;
+    }
+}