jojaba

This plugin makes it possible to restrict the access of posts contained in categories by setting a password and giving the impacted categories. The content and the excerpt of these posts are replaced by a password form that the user can fill out to get access. The WordPress generated feeds are modified (the description is replaced by a sentence that you can define).
Here’s the list of the settings (see screenshots for further infos):
<ul>
<li>Choose between session or cookie authentication</li>
<li>Set the password</li>
<li>Check the categories that has to be protected</li>
<li>Check the users granted to access the categories without password</li>
<li>Tell if the excerpt should be displayed or not in resources listing</li>
<li>Display a custom excerpt before password field</li>
<li>Set the info message that display before the password form</li>
<li>Set the placeholder in password field</li>
<li>Set the error message when typing the wrong password</li>
<li>Set the valdation button text</li>
<li>Set the text replacing the feed item description of protected posts</li>
<li>You can style the form using the available classes</li>
</ul>
Availabe languages : English (1.5), French (1.5), Simplified Chinese (thanks to Changmeng Hu, 1.4), German (1.4).
This plugin uses php Sessions (more secure) or a Cookie (less secure) to keep in mind the authenticated users. The password is crypted before it is stored. The regular feed content is filtered to avoid content display of restricted categories posts.

Access Category Password

protection type COOKIE is insecure.

If User set browser COOKIE, he can access protected posts.
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protection type がCOOKIEの場合は安全面に問題があります。

ある名称のCOOKIEをブラウザに埋め込めば保護された投稿にアクセス可能で、それはとても簡単にできます。

The protection type "COOKIE" is deprecated as insecure.

Protects posts in categories by setting a unique Password for all restricted categories.

Krešimir Karamazen

iainredmill

This plugin adds an onscreen keyboard powered by Javascript/JQuery, ported from Samuel Deering’s work on github with his permission under the above licence by Iain Redmill, now working within WordPress, allowing mouse based input or input when working from a touch screen device. Keyboard settings etc can be modified by editing the file. To add a keyboard, enter [oskb] within your page where you wish it to appear.
Apart from improving the working of the older version, the on-screen keyboard for password protected posts and pages in different flavors has been added recently. 
Onscreen keyboard for password protected posts and pages. Standard keyboard can still be used. 
Onscreen numerical keyboard for password protected posts and pages where password is numerical i.e. a pincode. Furthermore: 12 digit password is submitted automatically. (Passwords longer than 12 characters, of which the first 12 characters are numbers, are therefore impossible.) Standard keyboard can still be used (but in that case the auto-submit won’t work properly – you have to hit the submit button). General passwords can still be used by using standard keyboard.

Onscreen Keyboard

This plugin adds an onscreen keyboard powered by Javascript/JQuery to your page on demand.

Access Category Password vs Onscreen Keyboard