diff --git a/src/include/bagmetadata.hpp b/src/include/bagmetadata.hpp
index 09d227d..9b55cbc 100644
--- a/src/include/bagmetadata.hpp
+++ b/src/include/bagmetadata.hpp
@@ -3,6 +3,7 @@
 #include <string>
 #include <map>
 #include <list>
+#include "checksum.hpp"
 using namespace std;
 
 enum {
@@ -32,6 +33,8 @@ class Bagmetadata{
     bool has_bagmetadata();
     map<string,string> get_metadata();
     bool validate( list<string> & log );
+    bool has_oxum();
+    oxum_t get_oxum();
 };
 
 #endif
diff --git a/src/lib/bagmetadata.cpp b/src/lib/bagmetadata.cpp
index 3161fde..63c6ac7 100644
--- a/src/lib/bagmetadata.cpp
+++ b/src/lib/bagmetadata.cpp
@@ -62,7 +62,8 @@ Bagmetadata::Bagmetadata( string basedir ) {
         key = *(iter);
         value = (*++iter);
         Bagmetadata::metadata[ key ] = value;
-        // DEBUG: cout << "KEY="<<key<<" value="<<value<<endl;
+        // DEBUG: 
+        cout << "KEY="<<key<<" value="<<value<<endl;
       }
     }
   } else { // no file
@@ -77,7 +78,36 @@ map <string,string> Bagmetadata::get_metadata() {
 }
 
 bool Bagmetadata::validate(list<string> & log ) {
-  // TODO
-  return true;
+  bool is_valid = true;
+  return is_valid;
+}
+
+bool Bagmetadata::has_oxum() {
+  map<string, string>::iterator it;
+  it = this->metadata.find("Payload-Oxum");
+  if (it != this->metadata.end()) {
+    cout << "Oxum is: " << it->second << endl;
+        return true;
+  }
+  return false;
+}
+
+oxum_t Bagmetadata::get_oxum() {
+  oxum_t oxum;
+  oxum.octetcount=0;
+  oxum.streamcount=0;
+  map<string, string>::iterator it;
+  it = this->metadata.find("Payload-Oxum");
+  if (it != this->metadata.end()) {
+    // split by .
+    stringstream oxumstring(it->second);
+    string soctets;
+    string sstreams;
+    getline(oxumstring, soctets, '.');
+    getline(oxumstring, sstreams, '.');
+    oxum.octetcount = stoi( soctets );
+    oxum.streamcount = stoi( sstreams );
+  }
+  return oxum;
 }
 // vim: set tabstop=4 softtabstop=0 expandtab shiftwidth=4 smarttab
diff --git a/src/lib/payload.cpp b/src/lib/payload.cpp
index e217851..81c06cf 100644
--- a/src/lib/payload.cpp
+++ b/src/lib/payload.cpp
@@ -50,7 +50,6 @@ list<string> Payload::get_all_absolute_paths() {
 }
 
 bool Payload::validate( list<string> & log ) {
-  // TODO
   return true;
 }
 // vim: set tabstop=4
diff --git a/src/lib/validate_bag.cpp b/src/lib/validate_bag.cpp
index 981bdcb..4ba62d4 100644
--- a/src/lib/validate_bag.cpp
+++ b/src/lib/validate_bag.cpp
@@ -50,6 +50,22 @@ bool Bag::validate( list<string> & log ) {
     if (ret == false) {
       is_valid = false;
     }
+    if (this->bagmetadata_p->has_oxum()) {
+      // check oxum of payload
+      Checksum c;
+      list<string> files = this->payload_p->get_all_relative_paths();
+      oxum_t expected_oxum = this->bagmetadata_p->get_oxum();
+      oxum_t calculated_oxum = c.oxum_of_filelist( files );
+      if (expected_oxum.octetcount != calculated_oxum.octetcount) {
+        log.push_back("Bagit payload oxum octectcount=" + to_string(expected_oxum.octetcount) + " expected, but " + to_string(calculated_oxum.octetcount) + " found");
+        is_valid = false;
+      }
+      if (expected_oxum.streamcount != calculated_oxum.streamcount) {
+        log.push_back("Bagit payload oxum streamcount=" + to_string(expected_oxum.streamcount) + " expected, but " + to_string(calculated_oxum.streamcount) + " found");
+        is_valid = false;
+      }
+
+    }
   }
   /*
      if (NULL == this->fetchfile_p) {