Environment - PHP extension sodium

The php-sodium extension provides strong encryption capabilities in an easy and consistent way. This extension is required from Moodle 4.2.

Note that it is still highly recommended to use php-sodium in Moodle 3.11, 4.0 and 4.1, which also support the extension. Sites which do not have this extension installed use a php-openssl based solution as a fallback, which is considered sub-optimal. See MDL-71421 for more details.

It might be useful to copy the \server\php\libsodium.dll library to \server\apache\bin\libsodium.dll as mentioned in this forum discussion.

See also PHP: Sodium - Manual and the libsodium installation page.