wp-password-bcrypt is a WordPress plugin to replace WP’s outdated and insecure MD5-based password hashing with the modern and secure bcrypt.
It is written by roots.io people.
This plugin requires PHP >= 5.5.0 which introduced the built-in
password_hash and
password_verify functions.
See Improving WordPress Password Security for more background on this plugin and the password hashing issue.
This plugin is available for download for your site.