simon-git: putty (main): Simon Tatham

[Commits to Tartarus hosted VCS]

TL;DR:
  9529769b Windows PuTTYgen: make state->entropy into a strbuf.
  e7a69510 Windows PuTTYgen: remove state->collecting_entropy.
  5ad601ff Windows PuTTYgen: rate-limit entropy counter increment.

Repository:     https://git.tartarus.org/simon/putty.git
On the web:     https://git.tartarus.org/?p=simon/putty.git
Branch updated: main
Committer:      Simon Tatham <anakin at pobox.com>
Date:           2022-01-08 13:04:19

commit 9529769b6002eaaa44d293762a3cec159d628206
web diff https://git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=9529769b6002eaaa44d293762a3cec159d628206;hp=498c0a3abca2f3cfa5e1c663e60ea423bcd79672
Author: Simon Tatham <anakin at pobox.com>
Date:   Sat Jan 8 11:20:27 2022 +0000

    Windows PuTTYgen: make state->entropy into a strbuf.
    
    This offloads the memory management into centralised code which is
    better at it than the ad-hoc code here. Now I don't have to predict in
    advance how much memory the entropy will consume, and can change that
    decision on the fly.

 windows/puttygen.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

commit e7a695103fd51ae765ccf0460f15795adb74485e
web diff https://git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=e7a695103fd51ae765ccf0460f15795adb74485e;hp=9529769b6002eaaa44d293762a3cec159d628206
Author: Simon Tatham <anakin at pobox.com>
Date:   Sat Jan 8 11:23:46 2022 +0000

    Windows PuTTYgen: remove state->collecting_entropy.
    
    There's no point having a separate boolean flag. All we have to do is
    remember to NULL out the strbuf point state->entropy when we free the
    strbuf (which is a good idea in any case!), and then we can use the
    non-NULL-ness of that pointer as the indicator that we're currently
    collecting entropy.

 windows/puttygen.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

commit 5ad601ffcd5d09b5f22d998f71ce9ccdf35140f1
web diff https://git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=5ad601ffcd5d09b5f22d998f71ce9ccdf35140f1;hp=e7a695103fd51ae765ccf0460f15795adb74485e
Author: Simon Tatham <anakin at pobox.com>
Date:   Sat Jan 8 12:09:36 2022 +0000

    Windows PuTTYgen: rate-limit entropy counter increment.
    
    Some pointing devices (e.g. gaming mice) can be set to send
    mouse-movement events at an extremely high sample rate like 1kHz. This
    apparently translates into Windows genuinely sending WM_MOUSEMOVE
    messages at that rate. So if you're using one of those mice, then
    PuTTYgen's mouse-based entropy collection system will fill its buffer
    almost immediately, and give you no perceptible time to actually wave
    the mouse around.
    
    I think that in that situation, there's also likely to be a strong
    correlation between the contents of successive movement events,
    because human-controlled mouse movements aren't fractals - the more
    you zoom in on a little piece of one, the more it starts to look more
    and more like something moving in a straight line at constant speed,
    because the deviations from that happen on a larger time scale than
    you're seeing.
    
    So this commit adds a rate limit, not on the _collection_ of the data
    (we'll still take all the bits we can get, thanks!), but on the rate
    at which we increment the _counter_ for how much entropy we think
    we've collected so far. That way, the user still has to spend time
    wiggling the mouse back and forth in a way that varies with muscle
    motions and introduces randomness.

 windows/puttygen.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)