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.

net/http-net4-ajax.c@88:2857259fc2b4, 2019-04-10 (annotated)

Committer:
andrewboyson
Date:
Wed Apr 10 10:06:14 2019 +0000
Revision:
88:2857259fc2b4
Parent:
86:f3c9beec4ee7
Child:
89:615fb951df69
Made ARP and DNS entries in IPv6 and IPv4 pages update by ajax

Who changed what in which revision?

UserRevisionLine numberNew contents of line
andrewboyson 86:f3c9beec4ee7 1 #include <stdio.h>
andrewboyson 86:f3c9beec4ee7 2
andrewboyson 86:f3c9beec4ee7 3 #include "http.h"
andrewboyson 86:f3c9beec4ee7 4 #include "http-server.h"
andrewboyson 86:f3c9beec4ee7 5 #include "ar4.h"
andrewboyson 86:f3c9beec4ee7 6 #include "nr4.h"
andrewboyson 86:f3c9beec4ee7 7
andrewboyson 86:f3c9beec4ee7 8 void HttpNet4Ajax()
andrewboyson 86:f3c9beec4ee7 9 {
andrewboyson 86:f3c9beec4ee7 10 HttpOk("text/plain; charset=UTF-8", "no-cache", NULL, NULL);
andrewboyson 88:2857259fc2b4 11 Ar4SendAjax();
andrewboyson 86:f3c9beec4ee7 12 HttpAddChar('\f');
andrewboyson 88:2857259fc2b4 13 Nr4SendAjax();
andrewboyson 86:f3c9beec4ee7 14 }