JMeter was the best choice to populate the LDAP.
But.. in my case, OpenLDAP was configured not to accept any clear text passwords.
So, I could not login in with any of the random generated passwords I added via JMeter LDAP Request sampler.
This made me to write this extension to JMeter, which can be used in a generic way to generate message digest of a given text.
You can download the JAR file from here.
Then, you need to copy this to JMETER_HOME\lib\ext.
In your test plan, add a Java Request sampler to the thread group, just before where the digested text is needed. Now, select, org.wso2.apache.jmeter.message.digest.DigestGenerator.
Then you can set a hashing algorithm and which text to be digested. In that case, you can set a variable or text as it is. That's it - once done, you can access the digest value via ${password}.