From df0a2ef6aeb78b9ffcebdb692e0b02c870027ab5 Mon Sep 17 00:00:00 2001
From: Victor Parpoil <vparpoil@gmail.com>
Date: Fri, 31 Jan 2025 15:14:37 +0100
Subject: [PATCH] feat: enable rollback from argon2 to bcrypt

---
 .../accounts-password/password_argon_tests.js | 36 +++++++++++++++
 packages/accounts-password/password_server.js | 44 ++++++++++++++-----
 2 files changed, 69 insertions(+), 11 deletions(-)

diff --git a/packages/accounts-password/password_argon_tests.js b/packages/accounts-password/password_argon_tests.js
index 51eefc66e7..d580cf0512 100644
--- a/packages/accounts-password/password_argon_tests.js
+++ b/packages/accounts-password/password_argon_tests.js
@@ -92,8 +92,44 @@ if (Meteor.isServer) {
         await Meteor.users.removeAsync(userId);
     });
 
+    Tinytest.addAsync("passwords Argon - migration from argon2 encryption to bcrypt", async (test) => {
+        Accounts._options.argon2Enabled = true;
+        const username = Random.id();
+        const email = `${username}@bcrypt.com`;
+        const password = "password";
+        const userId = await Accounts.createUser(
+            {
+                username: username,
+                email: email,
+                password: password
+            }
+        );
+        Accounts._options.argon2Enabled = false;
+        let user = await Meteor.users.findOneAsync(userId);
+        const isValidArgon = await Accounts._checkPasswordAsync(user, password);
+        test.equal(isValidArgon.userId, userId, "checkPassword with argon2 - User ID should be returned");
+        test.equal(typeof isValidArgon.error, "undefined", "checkPassword with argon2 - No error should be returned");
 
 
+        // wait for defered execution of user update inside _checkPasswordAsync
+        await new Promise((resolve) => {
+            Meteor.setTimeout(async () => {
+                user = await Meteor.users.findOneAsync(userId);
+                // bcrypt has been unset and argon2 set
+                test.equal(typeof user.services.password.argon2, "undefined", "argon2 should be unset");
+                test.equal(typeof user.services.password.bcrypt, "string", "bcrypt should be set");
+                // password is still valid using argon2
+                const isValidBcrypt = await Accounts._checkPasswordAsync(user, password);
+                test.equal(isValidBcrypt.userId, userId, "checkPassword with argon2 - User ID should be returned");
+                test.equal(typeof isValidBcrypt.error, "undefined", "checkPassword with argon2 - No error should be returned");
+                resolve();
+            }, 100);
+        });
+
+        // cleanup
+        await Meteor.users.removeAsync(userId);
+    });
+
     const getUserHashArgon2Params = function (user) {
         const hash = user?.services?.password?.argon2;
         return Accounts._getArgon2Params(hash);
diff --git a/packages/accounts-password/password_server.js b/packages/accounts-password/password_server.js
index 8d738b7fd5..b6fd1c2348 100644
--- a/packages/accounts-password/password_server.js
+++ b/packages/accounts-password/password_server.js
@@ -134,10 +134,14 @@ Accounts._checkPasswordUserFields = { _id: 1, services: 1 };
 
 const isBcrypt = (hash) => {
   // bcrypt hashes start with $2a$ or $2b$
-  // argon2 hashes start with $argon2i$, $argon2d$ or $argon2id$
   return hash.startsWith("$2");
 };
 
+const isArgon = (hash) => {
+    // argon2 hashes start with $argon2i$, $argon2d$ or $argon2id$
+    return hash.startsWith("$argon2");
+}
+
 const updateUserPasswordDefered = (user, formattedPassword) => {
   Meteor.defer(async () => {
     await updateUserPassword(user, formattedPassword);
@@ -155,6 +159,9 @@ const getUpdatorForUserPassword = async (formattedPassword) => {
     return {
       $set: {
         "services.password.bcrypt": encryptedPassword
+      },
+      $unset: {
+        "services.password.argon2": 1
       }
     };
   }
@@ -208,19 +215,34 @@ const checkPasswordAsync = async (user, password) => {
 
   const argon2Enabled = Accounts._argon2Enabled();
   if (argon2Enabled === false) {
-    const hashRounds = getRoundsFromBcryptHash(hash);
-    const match = await bcryptCompare(formattedPassword, hash);
-    if (!match) {
-      result.error = Accounts._handleError("Incorrect password", false);
-    }
-    else if (hash) {
-      const paramsChanged = hashRounds !== Accounts._bcryptRounds();
-      // The password checks out, but the user's bcrypt hash needs to be updated
-      // to match current bcrypt settings
-      if (paramsChanged === true) {
+    if (isArgon(hash)) {
+      // this is a rollback feature, enabling to switch back from argon2 to bcrypt if needed
+      // TODO : deprecate this
+      console.warn("User has an argon2 password and argon2 is not enabled, rolling back to bcrypt encryption");
+      const match = await argon2.verify(hash, formattedPassword);
+      if (!match) {
+        result.error = Accounts._handleError("Incorrect password", false);
+      }
+      else{
+        // The password checks out, but the user's stored password needs to be updated to argon2
         updateUserPasswordDefered(user, { digest: formattedPassword, algorithm: "sha-256" });
       }
     }
+    else {
+      const hashRounds = getRoundsFromBcryptHash(hash);
+      const match = await bcryptCompare(formattedPassword, hash);
+      if (!match) {
+        result.error = Accounts._handleError("Incorrect password", false);
+      }
+      else if (hash) {
+        const paramsChanged = hashRounds !== Accounts._bcryptRounds();
+        // The password checks out, but the user's bcrypt hash needs to be updated
+        // to match current bcrypt settings
+        if (paramsChanged === true) {
+          updateUserPasswordDefered(user, { digest: formattedPassword, algorithm: "sha-256" });
+        }
+      }
+    }
   }
   else if (argon2Enabled === true) {
     if (isBcrypt(hash)) {