diff --git a/deno.lock b/deno.lock
index 41a2387..600baf8 100644
--- a/deno.lock
+++ b/deno.lock
@@ -2,6 +2,7 @@
   "version": "3",
   "redirects": {
     "https://deno.land/x/oak/mod.ts": "https://deno.land/x/oak@v12.6.1/mod.ts",
+    "https://denopkg.com/chiefbiiko/sha1/mod.ts": "https://denopkg.com/chiefbiiko/sha1@master/mod.ts",
     "https://unpkg.com/pure-rand/lib/esm/pure-rand.js": "https://unpkg.com/pure-rand@6.0.4/lib/esm/pure-rand.js"
   },
   "remote": {
@@ -144,6 +145,9 @@
     "https://deno.land/std@0.99.0/path/posix.ts": "f56c3c99feb47f30a40ce9d252ef6f00296fa7c0fcb6dd81211bdb3b8b99ca3b",
     "https://deno.land/std@0.99.0/path/separator.ts": "8fdcf289b1b76fd726a508f57d3370ca029ae6976fcde5044007f062e643ff1c",
     "https://deno.land/std@0.99.0/path/win32.ts": "77f7b3604e0de40f3a7c698e8a79e7f601dc187035a1c21cb1e596666ce112f8",
+    "https://deno.land/x/base64@v0.2.1/base.ts": "47dc8d68f07dc91524bdd6db36eccbe59cf4d935b5fc09f27357a3944bb3ff7b",
+    "https://deno.land/x/base64@v0.2.1/base64url.ts": "18bbf879b31f1f32cca8adaa2b6885ae325c2cec6a66c5817b684ca12c46ad5e",
+    "https://deno.land/x/base64@v0.2.1/mod.ts": "1cbdc4ba7229d3c6d1763fecdb9d46844777c7e153abb6dabea8b0dd01448db4",
     "https://deno.land/x/media_types@v2.7.1/db.ts": "1d95aa3fc1fe076638550640609394f0e157b18b430800e419aa7ece5c151d9c",
     "https://deno.land/x/media_types@v2.7.1/deps.ts": "cd4c31e4b5ed8c4d8c61bd2fb38a82d68d3fd2dcf6d43f22511cbe6d9d310e51",
     "https://deno.land/x/media_types@v2.7.1/mod.ts": "d63583b978d32eff8b76e1ae5d83cba2fb27baa90cc1bcb0ad15a06122ea8c19",
@@ -178,6 +182,9 @@
     "https://deno.land/x/static_files@1.1.6/src/deps.ts": "fb62be7a780339157bf692a619d6d02ea9662490deca275f488f9f9db917fc4a",
     "https://deno.land/x/static_files@1.1.6/src/types.ts": "ef201288626294e9e1b8ee85cdfe2cdfb282e4d78af445df1726050dfa0c0988",
     "https://deno.land/x/static_files@1.1.6/src/utils.ts": "9e6172dc97fed01e70a6b063c5afff40e20fe726b3bae0c5f0a962bad74b7107",
+    "https://denopkg.com/chiefbiiko/sha1@master/deps.ts": "434b70f37ed145ca5259353c96fdee1e7d1cd8c6a32baad9dce2aedc79d0a3bc",
+    "https://denopkg.com/chiefbiiko/sha1@master/mod.ts": "146a101c9776cc9c807053c93f23e4b321ade5251f65745df418f4a75d5fd27b",
+    "https://denopkg.com/chiefbiiko/std-encoding@v1.1.1/mod.ts": "e61017da4cef146863d614a961b4e61f1df14b72c906092bd02161f913e76522",
     "https://esm.sh/preact-render-to-string@5.1.19?deps=preact@10.5.15": "fba6961b9688151eeccc5425e05740009c3e7abee863615e626fb13e1d17e87a",
     "https://esm.sh/preact@10.19.2": "41f31ba8eecf666f08289f2205f57c45f74baba5be815a55c15c4cc61086143c",
     "https://esm.sh/preact@10.19.2/jsx-runtime": "2a4111d9aa667a3e3776ffd9082d00d63f6960c038d01620d79f80645ecc049d",
diff --git a/src/questions.js b/src/questions.js
index 8ceabb2..0d317ea 100644
--- a/src/questions.js
+++ b/src/questions.js
@@ -1,3 +1,6 @@
+import { sha1 } from "https://denopkg.com/chiefbiiko/sha1/mod.ts";
+
+
 function basicFrenchQuestion(argumentValue){
     return `Quel est la valeur retournée par la fonction si la valeur de l'argument x est ${argumentValue}?`
 }
@@ -7,7 +10,11 @@ function basicQuestionValidator(expected){
 }
 
 function basicQuestionMetaData(question){
-    return (x) => ({
+    const sourceHash = sha1(question.toString(), "utf8", "hex");
+    return (x, idx) => ({
+        sourceHash: sourceHash,
+        idx: idx,
+        id: `${sourceHash}-${idx}`,
         question_fr: basicFrenchQuestion(x),
         validate: basicQuestionValidator(question(x)),
         answer: question(x),
diff --git a/src/server.tsx b/src/server.tsx
index 79e6aee..0a6e565 100644
--- a/src/server.tsx
+++ b/src/server.tsx
@@ -65,6 +65,7 @@ function getQuestionPage(question: Question, urls: QuestionURLS){
             <div class="field">
                 <div class="control is-expanded">
                     <input class="input" type="text" placeholder="Answer" name="answer"></input>
+                    <input type="hidden" name="rendedingTimeStamp" value={Date.now()} ></input>
                 </div>
             </div>
             <div class="field is-grouped">
@@ -144,14 +145,49 @@ function getUrls(ctx): QuestionURLS{
     return {nextQuestionUrl, validationUrl, answerQuestionUrl};
 }
 
-apiRouter.post("/api/v1/random-questions/:seed/:idx/validate", async (ctx)=> {
-    const answer = (await ctx.request.body().value).get("answer");
+async function persistAnswer(ctx, form): Promise<void>{
+    const answer = form.get("answer");
+    const rendedingTimeStamp = form.get("rendedingTimeStamp");
+    const answeredTimestamp = Date.now();
+    const kv = await Deno.openKv();
     const q = getQuestion(ctx);
+
+    const username = ctx.request.headers.get('session');
+    const data = {
+        ip: ctx.request.ip,
+        url: ctx.request.url.toString(),
+        date: Date.now(),
+        domain: ctx.request.url.hostname,
+        hasRightResponse: isValidAnswer(q, answer),
+        answer,
+        rendedingTimeStamp,
+        answeredTimestamp
+    }
+    const baseKey = ["answer", q[1].id, username];
+    for(let i = 0 ; i < 1000; i++){
+        const key = baseKey.concat([i]);
+        const res = await kv.atomic()
+        .check({ key, versionstamp: null }) // `null` versionstamps mean 'no value'
+        .set(key, data)
+        .commit();
+        if (res.ok) {
+            return
+        }
+    }
+}
+
+apiRouter.post("/api/v1/random-questions/:seed/:idx/validate", async (ctx)=> {
+    const form = (await ctx.request.body().value);
+    const answer = form.get("answer");
+    const q = getQuestion(ctx);
+    
     if(isValidAnswer(q, answer)){
         processValidAnswer(ctx, getUrls(ctx).nextQuestionUrl)
     }else{
         processInvalidAnswer(ctx, getUrls(ctx).nextQuestionUrl)
     }
+    await persistAnswer(ctx, form);
+
 })
 
 apiRouter.get("/api/v1/random-questions/:seed/:idx/answer", (ctx)=> {
diff --git a/src/shared.ts b/src/shared.ts
index 513480c..1d2e67b 100644
--- a/src/shared.ts
+++ b/src/shared.ts
@@ -5,5 +5,6 @@ interface QuestionSource {
 export type QuestionMeta =  {
     question_fr: string,
     validate: (answer: string) => boolean,
-    answer: string | number
+    answer: string | number,
+    id: string,
 }
\ No newline at end of file