Configuration of Custom Crypt-Style
You can use custom Crypt-Types, but you should decide during installation which Type of encryption you want to use. By default SCryptImplementation is used:
- org.apache.openmeetings.util.crypt.SCryptImplementation - does use SCrypt for password hashing with salt
 
You can edit the config-key during Installation or later in the Administration Panel. But if you change it using the Administration-Panel previous passwords will not work anymore as they are encrypted with another algorithm.
Configuration of Custom Crypt-Style
To add your own crypt style you need to write a class which implements the interface: org.apache.openmeetings.util.crypt.ICrypt 
 Example of an Implementation: 
 SHA256Implementation.java 
 MD5Implementation.java 
To add your own Encryption-Class you need to add your class to the OpenMeetings-Webapp (make it available to the webapp-classpath) and use your custom-class-name instead of org.apache.openmeetings.util.crypt.SCryptImplementation during the Installation or at runtime by editing the config-key crypt.class.name
Configuration of Custom Crypt-Style
credits goto Mika for sharing his Implementation of the MD5Crypt-Style