diff --git a/package-lock.json b/package-lock.json
index 7b2cd07d..7f74a256 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -18,9 +18,11 @@
         "cors": "^2.8.5",
         "cron": "^2.3.1",
         "express": "^4.18.2",
+        "fp-ts": "^2.16.1",
         "jsonwebtoken": "^9.0.0",
         "le-coffre-resources": "git@github.com:smart-chain-fr/leCoffre-resources.git#v2.77",
         "module-alias": "^2.2.2",
+        "monocle-ts": "^2.3.13",
         "multer": "^1.4.5-lts.1",
         "next": "^13.1.5",
         "node-cache": "^5.1.2",
@@ -2474,6 +2476,11 @@
         "node": ">= 0.6"
       }
     },
+    "node_modules/fp-ts": {
+      "version": "2.16.1",
+      "resolved": "https://registry.npmjs.org/fp-ts/-/fp-ts-2.16.1.tgz",
+      "integrity": "sha512-by7U5W8dkIzcvDofUcO42yl9JbnHTEDBrzu3pt5fKT+Z4Oy85I21K80EYJYdjQGC2qum4Vo55Ag57iiIK4FYuA=="
+    },
     "node_modules/fresh": {
       "version": "0.5.2",
       "license": "MIT",
@@ -3901,6 +3908,14 @@
       "version": "2.2.3",
       "license": "MIT"
     },
+    "node_modules/monocle-ts": {
+      "version": "2.3.13",
+      "resolved": "https://registry.npmjs.org/monocle-ts/-/monocle-ts-2.3.13.tgz",
+      "integrity": "sha512-D5Ygd3oulEoAm3KuGO0eeJIrhFf1jlQIoEVV2DYsZUMz42j4tGxgct97Aq68+F8w4w4geEnwFa8HayTS/7lpKQ==",
+      "peerDependencies": {
+        "fp-ts": "^2.5.0"
+      }
+    },
     "node_modules/ms": {
       "version": "2.0.0",
       "license": "MIT"
diff --git a/package.json b/package.json
index 9487dca3..57955a72 100644
--- a/package.json
+++ b/package.json
@@ -51,9 +51,11 @@
     "cors": "^2.8.5",
     "cron": "^2.3.1",
     "express": "^4.18.2",
+    "fp-ts": "^2.16.1",
     "jsonwebtoken": "^9.0.0",
     "le-coffre-resources": "git@github.com:smart-chain-fr/leCoffre-resources.git#v2.77",
     "module-alias": "^2.2.2",
+    "monocle-ts": "^2.3.13",
     "multer": "^1.4.5-lts.1",
     "next": "^13.1.5",
     "node-cache": "^5.1.2",
diff --git a/src/common/optics/notary/index.ts b/src/common/optics/notary/index.ts
new file mode 100644
index 00000000..4e9441e2
--- /dev/null
+++ b/src/common/optics/notary/index.ts
@@ -0,0 +1,29 @@
+import * as Optics from "monocle-ts";
+import * as Traversal from "monocle-ts/Traversal";
+import * as Array from "fp-ts/Array";
+
+import { Document, File, OfficeFolder } from "le-coffre-resources/dist/Notary";
+
+/**
+ * Lenses
+ */
+export const folderDocumentsLens = Optics.Lens.fromNullableProp<OfficeFolder>()("documents", []);
+export const documentFilesLens = Optics.Lens.fromNullableProp<Document>()("files", []);
+export const fileHashLens = Optics.Lens.fromProp<File>()("hash");
+
+/**
+ * Traversals
+ */
+export const documentsTraversal = Optics.fromTraversable(Array.Traversable)<Document>();
+export const filesTraversal = Optics.fromTraversable(Array.Traversable)<File>();
+
+export const folderHashesTraversal = folderDocumentsLens
+	.composeTraversal(documentsTraversal)
+	.composeLens(documentFilesLens)
+	.composeTraversal(filesTraversal)
+	.composeLens(fileHashLens);
+
+/**
+ * Getters
+ */
+export const getFolderHashes = (folder: OfficeFolder) => Traversal.getAll(folder)(folderHashesTraversal);