46 lines
2.1 KiB
Markdown
46 lines
2.1 KiB
Markdown
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# Security
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Espanso has always been designed with a strong focus on security.
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In the following section, there is an overview of the critical security
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components.
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If you have any doubt, don't hesitate to contact me.
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## Architecture
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In its most basic form, a text expander is composed of two parts:
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* A **global key detector** that intercepts the keys pressed by the user,
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in order to determine if a trigger was typed.
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* A **key injection mechanism** that injects the
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final text into the current application, a process known as *expansion*.
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At this point, some of you may think that espanso is acting as a keylogger,
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due to the *global key detector* we mentioned before. The good news is, **it's not!**
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While espanso detects key presses as a keylogger would do,
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**it doesn't log anything**. Moreover, to further reduce risks, espanso only
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stores in memory the last 3 chars by default (you can change this amount by
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setting the `backspace_limit` parameter in the config) and this is needed
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to allow the user to correct wrongly typed triggers by pressing backspace,
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up to 3 characters.
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The matching part is implemented with an efficient [data structure](https://github.com/federico-terzi/espanso/blob/master/src/matcher/scrolling.rs)
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that keeps track of the compatible matches in a "rolling" basis. So that in the worst case scenario,
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the longest sequence of chars kept in memory would be equal to the longest trigger.
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And of course, if you don't trust me you can examine all the code! That's
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the wonderful thing about open source :)
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### Implementation
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The *global key detector* is implemented on top of various OS-dependent APIs, in particular:
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* On Windows, it uses the [RawInput API](https://docs.microsoft.com/en-us/windows/win32/inputdev/raw-input).
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* On macOS, it uses [addGlobalMonitorForEvents](https://developer.apple.com/documentation/appkit/nsevent/1535472-addglobalmonitorforevents).
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* On Linux, it uses the [X Record Extension](https://www.x.org/releases/X11R7.6/doc/libXtst/recordlib.html).
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## Reporting Security Issues
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To report a security issue, please email me at federicoterzi96[at]gmail.com
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