Andrew Boyson / web

Common stuff for all my devices' web server pages: css, login, log, ipv4, ipv6, firmware update, clock, reset info etc.

Dependents:   oldheating gps motorhome heating

Security

A password has to be set whenever there has been a software reset. Resets following faults or power on do not require a new password as the hash is restored from the RTC GPREG register.

The password is not saved on the device; instead a 32 bit hash of the password is saved. It would take 2^31 attempts to brute force the password: this could be done in under a month if an attempt were possible every millisecond. To prevent this a 200 ms delay is introduced in the reply to the login form, that gives a more reasonable 13 years to brute force the password.

Once the password is accepted a random session id is created. This is 36 bit to give six base 64 characters but without an extra delay. If an attempt could be made every ms then this would still take over a year to brute force.

The most likely attack would to use a dictionary with, say, 10 million entries against the password which would still take 20 days to do.

Diff: common/web-ajax-class.js

Revision:
156:005785e4740e
Parent:
140:8951a8b45289
--- a/common/web-ajax-class.js	Sun Jan 24 15:06:33 2021 +0000
+++ b/common/web-ajax-class.js	Sun Jan 24 18:54:27 2021 +0000
@@ -15,7 +15,9 @@
 let   ajaxXhr_                        =  null;
 let   ajaxMsCountAtAjaxSend_          =     0;
 const ajaxTickMs_                     =   100;
+const ajaxQuickUpdateMs_              =  1000;
 const ajaxUpdateMs_                   = 10000;
+let   ajaxDoQuickUpdate_              = false;
 
 //Private utilities
 function ajaxGetElementOrNull_(elementName) //Returns the element if it: exists; block is overidden; does not have focus
@@ -103,12 +105,14 @@
         ajaxXhr_.open('GET', ajaxServer_, true);
     }
     ajaxXhr_.send();
+    ajaxDoQuickUpdate_     = false;
     ajaxMsCountAtAjaxSend_ = ajaxMs_;
 }
 function AjaxSendNameValue(name, value) //From html
 {
     ajaxOverrideBlockUpdateOnFocus_ = true; //Request has come from an update
     ajaxSendNameValue_(name, value);
+    ajaxDoQuickUpdate_              = true; //Make the next request a quick one
 }
 
 //Private functions
@@ -116,6 +120,10 @@
 {
     ajaxMs_ += ajaxTickMs_; //Don't use Date.now() as we don't know when the PC's clock will be updated around a leap second
     if (ajaxMs_ >= ajaxMsCountAtAjaxSend_ + ajaxUpdateMs_) ajaxSendNameValue_('', '');
+    if (ajaxDoQuickUpdate_)
+    {
+        if (ajaxMs_ >= ajaxMsCountAtAjaxSend_ + ajaxQuickUpdateMs_) ajaxSendNameValue_('', '');
+    }
     if (ajaxOnTick_) ajaxOnTick_();
 }
 function ajaxInit_()