diff --git a/libopenfpga/libfabrickey/key_examples/key_example.xml b/libopenfpga/libfabrickey/key_examples/key_example.xml
index 49140b6e0..b9b0aa814 100644
--- a/libopenfpga/libfabrickey/key_examples/key_example.xml
+++ b/libopenfpga/libfabrickey/key_examples/key_example.xml
@@ -1,7 +1,9 @@
 <fabric_key>
-  <key id="0" name="sb" value="0"/>
-  <key id="2" name="cb" value="10"/>
-  <key id="1" name="sb" value="7"/>
-  <key id="3" name="clb" value="53"/>
-  <key id="4" name="bram" value="32"/>
+  <region id="0">
+    <key id="0" name="sb" value="0"/>
+    <key id="2" name="cb" value="10"/>
+    <key id="1" name="sb" value="7"/>
+    <key id="3" name="clb" value="53"/>
+    <key id="4" name="bram" value="32"/>
+  </region>
 </fabric_key>
diff --git a/libopenfpga/libfabrickey/src/fabric_key.cpp b/libopenfpga/libfabrickey/src/fabric_key.cpp
index b4bf5efac..dfe445c75 100644
--- a/libopenfpga/libfabrickey/src/fabric_key.cpp
+++ b/libopenfpga/libfabrickey/src/fabric_key.cpp
@@ -1,4 +1,7 @@
+#include <algorithm>
+
 #include "vtr_assert.h"
+#include "vtr_log.h"
 
 #include "fabric_key.h"
 
@@ -20,24 +23,31 @@ FabricKey::fabric_key_range FabricKey::keys() const {
   return vtr::make_range(key_ids_.begin(), key_ids_.end());
 }
 
+FabricKey::fabric_region_range FabricKey::regions() const {
+  return vtr::make_range(region_ids_.begin(), region_ids_.end());
+}
+
 /************************************************************************
  * Public Accessors : Basic data query 
  ***********************************************************************/
-/* Access the name of a key */
+std::vector<FabricKeyId> FabricKey::region_keys(const FabricRegionId& region_id) const {
+  /* validate the region_id */
+  VTR_ASSERT(valid_region_id(region_id));
+  return region_key_ids_[region_id]; 
+}
+
 std::string FabricKey::key_name(const FabricKeyId& key_id) const {
   /* validate the key_id */
   VTR_ASSERT(valid_key_id(key_id));
   return key_names_[key_id]; 
 }
 
-/* Access the value of a key */
 size_t FabricKey::key_value(const FabricKeyId& key_id) const {
   /* validate the key_id */
   VTR_ASSERT(valid_key_id(key_id));
   return key_values_[key_id]; 
 }
 
-/* Access the alias of a key */
 std::string FabricKey::key_alias(const FabricKeyId& key_id) const {
   /* validate the key_id */
   VTR_ASSERT(valid_key_id(key_id));
@@ -51,20 +61,78 @@ bool FabricKey::empty() const {
 /************************************************************************
  * Public Mutators
  ***********************************************************************/
+
+void FabricKey::reserve_regions(const size_t& num_regions) {
+  region_ids_.reserve(num_regions);
+  region_key_ids_.reserve(num_regions);
+}
+
+FabricRegionId FabricKey::create_region() {
+  /* Create a new id */
+  FabricRegionId region = FabricRegionId(region_ids_.size());
+  region_ids_.push_back(region);
+  region_key_ids_.emplace_back();
+  
+  return region;
+}
+
+void FabricKey::reserve_region_keys(const FabricRegionId& region_id,
+                                    const size_t& num_keys) {
+  /* validate the region_id */
+  VTR_ASSERT(valid_region_id(region_id));
+
+  region_key_ids_[region_id].reserve(num_keys);
+}
+
+void FabricKey::add_key_to_region(const FabricRegionId& region_id,
+                                  const FabricKeyId& key_id) {
+  /* validate the key_id */
+  VTR_ASSERT(valid_key_id(key_id));
+  /* validate the region_id */
+  VTR_ASSERT(valid_region_id(region_id));
+
+  /* Check if the key is already in the region */
+  if (region_key_ids_[region_id].end() != std::find(region_key_ids_[region_id].begin(),
+                                                    region_key_ids_[region_id].end(),
+                                                    key_id)) {
+    VTR_LOG_WARN("Try to add a key '%s' which is already in the region '%lu'!\n",
+                 key_name(key_id).c_str(),
+                 size_t(region_id));
+    VTR_ASSERT(region_id == key_regions_[key_id]);
+    return; /* Nothing to do but leave a warning! */
+  }
+
+  /* Register the key in the region */
+  region_key_ids_[region_id].push_back(key_id);
+
+  /* If the key is already in another region, we will error out */
+  if ( (true == valid_region_id(key_regions_[key_id])) 
+    && (region_id != key_regions_[key_id])) { 
+    VTR_LOG_ERROR("Try to add a key '%s' to region '%lu' but it is already in another region '%lu'!\n",
+                 key_name(key_id).c_str(),
+                 size_t(key_regions_[key_id]),
+                 size_t(region_id));
+    exit(1);
+  }
+
+  key_regions_[key_id] = region_id;
+}
+
 void FabricKey::reserve_keys(const size_t& num_keys) {
   key_ids_.reserve(num_keys);
   key_names_.reserve(num_keys);
   key_values_.reserve(num_keys);
+  key_regions_.reserve(num_keys);
   key_alias_.reserve(num_keys);
 }
 
-/* Create a new key and add it to the library, return an id */
 FabricKeyId FabricKey::create_key() {
   /* Create a new id */
   FabricKeyId key = FabricKeyId(key_ids_.size());
   key_ids_.push_back(key);
   key_names_.emplace_back();
   key_values_.emplace_back();
+  key_regions_.emplace_back(FabricRegionId::INVALID());
   key_alias_.emplace_back();
   
   return key;
@@ -98,6 +166,10 @@ void FabricKey::set_key_alias(const FabricKeyId& key_id,
  * Internal invalidators/validators 
  ***********************************************************************/
 /* Validators */
+bool FabricKey::valid_region_id(const FabricRegionId& region_id) const {
+  return ( size_t(region_id) < region_ids_.size() ) && ( region_id == region_ids_[region_id] ); 
+}
+
 bool FabricKey::valid_key_id(const FabricKeyId& key_id) const {
   return ( size_t(key_id) < key_ids_.size() ) && ( key_id == key_ids_[key_id] ); 
 }
diff --git a/libopenfpga/libfabrickey/src/fabric_key.h b/libopenfpga/libfabrickey/src/fabric_key.h
index 4ca678722..0ca1d252d 100644
--- a/libopenfpga/libfabrickey/src/fabric_key.h
+++ b/libopenfpga/libfabrickey/src/fabric_key.h
@@ -15,41 +15,94 @@
 
 /********************************************************************
  * A data structure to describe a secure key for fabric organization
+ * A fabric may consist of multiple regions
+ * Each region contains a number of keys
+ * 
+ * Note that:
+ *   - each key can only be defined in one unique region 
  *
  * Typical usage:
  * --------------
  *   // Create an empty fabric key
  *   FabricKey fabric_key;
+ *   // Create a region
+ *   FabricRegionId region = fabric_key.create_region();
  *   // Add a key with name and value
- *   FabricKeyId key = fabic_key.create_key(key_name, key_value);
+ *   FabricKeyId key = fabric_key.create_key(key_name, key_value);
+ *   // Affilate a key to a region
+ *   fabric_key.add_key_to_region(region, key);
  *
  *******************************************************************/
 class FabricKey {
   public: /* Types */
     typedef vtr::vector<FabricKeyId, FabricKeyId>::const_iterator fabric_key_iterator;
+    typedef vtr::vector<FabricRegionId, FabricRegionId>::const_iterator fabric_region_iterator;
     /* Create range */
+    typedef vtr::Range<fabric_region_iterator> fabric_region_range;
     typedef vtr::Range<fabric_key_iterator> fabric_key_range;
   public:  /* Constructors */
     FabricKey();
   public: /* Accessors: aggregates */
     fabric_key_range keys() const;
+    fabric_region_range regions() const;
   public: /* Public Accessors: Basic data query */
+    /* Access all the keys of a region */
+    std::vector<FabricKeyId> region_keys(const FabricRegionId& region_id) const;
+
+    /* Access the name of a key */
     std::string key_name(const FabricKeyId& key_id) const;
+
+    /* Access the value of a key */
     size_t key_value(const FabricKeyId& key_id) const;
+
+    /* Access the alias of a key */
     std::string key_alias(const FabricKeyId& key_id) const;
+
+    /* Check if there are any keys */
     bool empty() const;
+
   public: /* Public Mutators: model-related */
+
+    /* Reserve a number of regions to be memory efficent */
+    void reserve_regions(const size_t& num_regions);
+
+    /* Create a new region and add it to the library, return an id */
+    FabricRegionId create_region();
+
+    /* Reserve the memory space for keys under a region, to be memory efficient */
+    void reserve_region_keys(const FabricRegionId& region_id,
+                             const size_t& num_keys);
+
+    /* Add a key to a region */
+    void add_key_to_region(const FabricRegionId& region_id,
+                           const FabricKeyId& key_id);
+
+    /* Reserve a number of keys to be memory efficent */
     void reserve_keys(const size_t& num_keys);
+
+    /* Create a new key and add it to the library, return an id */
     FabricKeyId create_key();
+
+    /* Configure attributes of a key */
     void set_key_name(const FabricKeyId& key_id,
                       const std::string& name);
+
     void set_key_value(const FabricKeyId& key_id,
                        const size_t& value);
+
     void set_key_alias(const FabricKeyId& key_id,
                        const std::string& alias);
+
   public: /* Public invalidators/validators */
+    bool valid_region_id(const FabricRegionId& region_id) const;
     bool valid_key_id(const FabricKeyId& key_id) const;
   private: /* Internal data */
+    /* Unique ids for each region */
+    vtr::vector<FabricRegionId, FabricRegionId> region_ids_;
+
+    /* Key ids for each region */
+    vtr::vector<FabricRegionId, std::vector<FabricKeyId>> region_key_ids_;
+
     /* Unique ids for each key */
     vtr::vector<FabricKeyId, FabricKeyId> key_ids_;
 
@@ -59,6 +112,9 @@ class FabricKey {
     /* Values for each key */
     vtr::vector<FabricKeyId, size_t> key_values_;
 
+    /* Region for each key */
+    vtr::vector<FabricKeyId, FabricRegionId> key_regions_;
+
     /* Optional alias for each key, with which a key can also be represented */
     vtr::vector<FabricKeyId, std::string> key_alias_;
 };
diff --git a/libopenfpga/libfabrickey/src/fabric_key_fwd.h b/libopenfpga/libfabrickey/src/fabric_key_fwd.h
index 523eaeab8..249093fd2 100644
--- a/libopenfpga/libfabrickey/src/fabric_key_fwd.h
+++ b/libopenfpga/libfabrickey/src/fabric_key_fwd.h
@@ -12,8 +12,10 @@
 
 #include "vtr_strong_id.h"
 
+struct fabric_region_id_tag;
 struct fabric_key_id_tag;
 
+typedef vtr::StrongId<fabric_region_id_tag> FabricRegionId;
 typedef vtr::StrongId<fabric_key_id_tag> FabricKeyId;
 
 /* Short declaration of class */