ActivityPub: Digest header is mandatory now for POST requests

2 files changed, 38 insertions, 15 deletions

diff --git a/src/main/java/com/juick/ActivityPubManager.java b/src/main/java/com/juick/ActivityPubManager.java
index e3b1ac8e..22fe826f 100644
--- a/src/main/java/com/juick/ActivityPubManager.java
+++ b/src/main/java/com/juick/ActivityPubManager.java
@@ -54,6 +54,7 @@ import java.io.IOException;
 import java.io.StringWriter;
 import java.io.Writer;
 import java.net.URI;
+import java.security.NoSuchAlgorithmException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -104,7 +105,7 @@ public class ActivityPubManager implements ActivityListener, NotificationListene
                 signatureManager.post(me, follower, accept);
                 socialService.addFollower(followedUser, follower.getId());
                 logger.info("Follower added for {}", followedUser.getName());
-            } catch (IOException e) {
+            } catch (IOException | NoSuchAlgorithmException e) {
                 logger.info("activitypub exception", e);
             }
         }
@@ -145,7 +146,7 @@ public class ActivityPubManager implements ActivityListener, NotificationListene
             try {
                 logger.info("Deletion to follower {}", follower.getId());
                 signatureManager.post(me, follower, delete);
-            } catch (IOException e) {
+            } catch (IOException | NoSuchAlgorithmException e) {
                 logger.warn("activitypub exception", e);
             }
         });
@@ -194,7 +195,7 @@ public class ActivityPubManager implements ActivityListener, NotificationListene
             try {
                 logger.info("Update to follower {}", follower.getId());
                 signatureManager.post(me, follower, update);
-            } catch (IOException e) {
+            } catch (IOException | NoSuchAlgorithmException e) {
                 logger.warn("activitypub exception", e);
             }
         });
@@ -239,7 +240,7 @@ public class ActivityPubManager implements ActivityListener, NotificationListene
                 create.setObject(note);
                 try {
                     signatureManager.post(me, follower, create);
-                } catch (IOException e) {
+                } catch (IOException | NoSuchAlgorithmException e) {
                     logger.warn("activitypub exception", e);
                 }
             }
@@ -386,7 +387,7 @@ public class ActivityPubManager implements ActivityListener, NotificationListene
                 try {
                     logger.info("Announcing top: {}", message.getMid());
                     signatureManager.post(me, (Person)person, announce);
-                } catch (IOException e) {
+                } catch (IOException | NoSuchAlgorithmException e) {
                     logger.warn("activitypub exception", e);
                 }
             }, () -> logger.warn("Follower not found: {}", acct));
diff --git a/src/main/java/com/juick/SignatureManager.java b/src/main/java/com/juick/SignatureManager.java
index fc92f39a..fed6c368 100644
--- a/src/main/java/com/juick/SignatureManager.java
+++ b/src/main/java/com/juick/SignatureManager.java
@@ -26,6 +26,7 @@ import com.juick.www.api.activity.model.Context;
 import com.juick.www.api.activity.model.objects.Person;
 import com.juick.www.api.webfinger.model.Account;
 import com.juick.www.api.webfinger.model.Link;
+import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.http.HttpEntity;
@@ -34,6 +35,8 @@ import org.springframework.http.HttpMethod;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
+import org.tomitribe.auth.signatures.Base64;
+import org.tomitribe.auth.signatures.MissingRequiredHeaderException;
 import org.tomitribe.auth.signatures.Signature;
 import org.tomitribe.auth.signatures.Signer;
 import org.tomitribe.auth.signatures.Verifier;
@@ -43,10 +46,13 @@ import javax.inject.Inject;
 import java.io.IOException;
 import java.net.URI;
 import java.security.Key;
+import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.security.SignatureException;
 import java.time.Instant;
+import java.util.Arrays;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 
@@ -63,35 +69,51 @@ public class SignatureManager {
     @Inject
     private RestTemplate apClient;
 
-    public void post(Person from, Person to, Context data) throws IOException {
+    public void post(Person from, Person to, Context data) throws IOException, NoSuchAlgorithmException {
         UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(to.getInbox());
         URI inbox = uriComponentsBuilder.build().toUri();
         Instant now = Instant.now();
         String requestDate = DateFormattersHolder.getHttpDateFormatter().format(now);
         String host = inbox.getPort() > 0 ? String.format("%s:%d", inbox.getHost(), inbox.getPort()) : inbox.getHost();
-        String signatureString = addSignature(from, host, "POST", inbox.getPath(), requestDate);
+        var finalContext = Context.build(data);
+        var payload = jsonMapper.writeValueAsString(finalContext);
+        final byte[] digest = MessageDigest.getInstance("SHA-256").digest(payload.getBytes()); // (1)
+        final String digestHeader = "SHA-256=" + new String(Base64.encodeBase64(digest));
+        String signatureString = addSignature(from, host, "POST", inbox.getPath(), requestDate, digestHeader);
 
         HttpHeaders requestHeaders = new HttpHeaders();
         requestHeaders.add("Content-Type", Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE);
         requestHeaders.add("Date", requestDate);
         requestHeaders.add("Host", host);
+        requestHeaders.add("Digest", digestHeader);
         requestHeaders.add("Signature", signatureString);
-        HttpEntity<Context> request = new HttpEntity<>(Context.build(data), requestHeaders);
-        logger.info("Sending context to {}: {}", to.getId(), jsonMapper.writeValueAsString(data));
+        HttpEntity<Context> request = new HttpEntity<>(finalContext, requestHeaders);
+        logger.info("Sending context to {}: {}", to.getId(), payload);
         ResponseEntity<Void> response = apClient.postForEntity(inbox, request, Void.class);
         logger.info("Remote response: {}", response.getStatusCodeValue());
     }
 
-    public String addSignature(Person from, String host, String method, String path, String dateString) throws IOException {
-        return addSignature(from, host, method, path, dateString, keystoreManager);
+    public String addSignature(Person from, String host, String method,
+                               String path, String dateString, String digestHeader)
+            throws IOException {
+        return addSignature(from, host, method, path, dateString,
+                digestHeader, keystoreManager);
     }
 
-    public String addSignature(Person from, String host, String method, String path, String dateString, KeystoreManager keystoreManager) throws IOException {
-        Signature templateSignature = new Signature(from.getPublicKey().getId(), "rsa-sha256", null,
-                "(request-target)", "host", "date");
+    public String addSignature(Person from, String host, String method,
+                               String path, String dateString, String digestHeader,
+                               KeystoreManager keystoreManager) throws IOException {
+        List<String> requiredHeaders = StringUtils.isEmpty(digestHeader) ?
+                Arrays.asList("(request-target)", "host", "date")
+                : Arrays.asList("(request-target)", "host", "date", "digest");
+        Signature templateSignature = new Signature(from.getPublicKey().getId(),
+                "rsa-sha256", null, requiredHeaders);
         Map<String, String> headers = new HashMap<>();
         headers.put("host", host);
         headers.put("date", dateString);
+        if (StringUtils.isNotEmpty(digestHeader)) {
+            headers.put("digest", digestHeader);
+        }
         Signer signer = new Signer(keystoreManager.getPrivateKey(), templateSignature);
         Signature signature = signer.sign(method, path, headers);
         // remove "Signature: " from result
@@ -122,7 +144,7 @@ public class SignatureManager {
                 } else {
                     return AnonymousUser.INSTANCE;
                 }
-            } catch (NoSuchAlgorithmException | SignatureException | IOException e) {
+            } catch (NoSuchAlgorithmException | SignatureException | MissingRequiredHeaderException | IOException e) {
                 logger.warn("Invalid signature {}", signatureString);
             }
         } else {