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.
login/web-login-session-name.c@103:91194cc19bbb, 2019-04-27 (annotated)
- Committer:
- andrewboyson
- Date:
- Sat Apr 27 09:25:28 2019 +0000
- Revision:
- 103:91194cc19bbb
- Parent:
- login/http-login-session-name.c@82:980a393ff4dc
- Child:
- 109:3e82f62c7e1f
Renamed everything from Http to Web
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
andrewboyson | 71:d6aacc7d62ab | 1 | #include "page.h" |
andrewboyson | 71:d6aacc7d62ab | 2 | |
andrewboyson | 82:980a393ff4dc | 3 | #define SESSION_LIFE 10 * 365 * 24 * 60 * 60 |
andrewboyson | 82:980a393ff4dc | 4 | |
andrewboyson | 71:d6aacc7d62ab | 5 | //Do not use ' ', ';', '=' as they are part of the cookie protocol: name1=value1; name2=value2; name3=value3 etc |
andrewboyson | 71:d6aacc7d62ab | 6 | static char sessionName[9]; //Limit the name to 8 characters (plus terminating zero) to keep things quick |
andrewboyson | 71:d6aacc7d62ab | 7 | |
andrewboyson | 103:91194cc19bbb | 8 | char* WebLoginSessionNameGet() |
andrewboyson | 71:d6aacc7d62ab | 9 | { |
andrewboyson | 71:d6aacc7d62ab | 10 | return sessionName; |
andrewboyson | 71:d6aacc7d62ab | 11 | } |
andrewboyson | 71:d6aacc7d62ab | 12 | |
andrewboyson | 103:91194cc19bbb | 13 | void WebLoginSessionNameCreate() |
andrewboyson | 71:d6aacc7d62ab | 14 | { |
andrewboyson | 71:d6aacc7d62ab | 15 | //Make the session name from the site name - eg "Heating" and "GPS Clock" will be "heat_sid" and "gpsc_sid" |
andrewboyson | 71:d6aacc7d62ab | 16 | int i = 0; |
andrewboyson | 71:d6aacc7d62ab | 17 | int j = 0; |
andrewboyson | 71:d6aacc7d62ab | 18 | while (1) |
andrewboyson | 71:d6aacc7d62ab | 19 | { |
andrewboyson | 71:d6aacc7d62ab | 20 | if (i >= sizeof(sessionName) - 4 - 1) break; //Leave room for the "_sid" and the terminating NUL character |
andrewboyson | 71:d6aacc7d62ab | 21 | char c = PageSite[j++]; |
andrewboyson | 71:d6aacc7d62ab | 22 | if (!c) break; //Stop if run out of site name |
andrewboyson | 71:d6aacc7d62ab | 23 | if (c >= 'A' && c <= 'Z') c |= 0x20; //Make lower case |
andrewboyson | 71:d6aacc7d62ab | 24 | if (c < 'a' || c > 'z') continue; //Skip anything other than letters |
andrewboyson | 71:d6aacc7d62ab | 25 | sessionName[i++] = c; //Add the first characters of the site name for which there is room |
andrewboyson | 71:d6aacc7d62ab | 26 | } |
andrewboyson | 71:d6aacc7d62ab | 27 | for (int k = 0; k < 4; k++) //Add "_sid" |
andrewboyson | 71:d6aacc7d62ab | 28 | { |
andrewboyson | 71:d6aacc7d62ab | 29 | sessionName[i++] = "_sid"[k]; |
andrewboyson | 71:d6aacc7d62ab | 30 | } |
andrewboyson | 71:d6aacc7d62ab | 31 | sessionName[i] = 0; //Add the terminating NUL character |
andrewboyson | 71:d6aacc7d62ab | 32 | } |
andrewboyson | 82:980a393ff4dc | 33 | |
andrewboyson | 103:91194cc19bbb | 34 | int WebLoginSessionNameLife() |
andrewboyson | 82:980a393ff4dc | 35 | { |
andrewboyson | 82:980a393ff4dc | 36 | return SESSION_LIFE; |
andrewboyson | 82:980a393ff4dc | 37 | } |