This plugin is outdated and might not be supported anymore
Details
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This plugin allows you to require a secret key that is passed via the URL: http://example.com/post-title/?key=[string]
Specify the key in a custom value called “key” with the [string] or use the built in widget.

Stable version of the plugin are pushed to the WordPress repository,
but the latest version of the plugin can be found at:
https://bitbucket.org/excion/wpkeyme/

Issues/Bugs: https://bitbucket.org/excion/wpkeyme/issues

Details

Plugin code:
wpkeyme
Plugin version:
0.2.1
Outdated:
Yes
WP version:
3.0.1 or higher
PHP version:
or higher
Test up to WP version:
3.5.2
Total installations:
10
Last updated:
2013-04-15
Rating:
Times rated:
0
key
post
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token