Encrypt password using Nintex

Hi All,

I've an requirement, that using Execute SQL action item i need to pass the plain text  password in Connection string. This password is not coming from AD, so i need to encrypt the password instead of giving plain text. If we create workflow contrasts also we need to store the password as plain string at site collection settings and this doesn't help as well.  

So is there any approach to achieve this requirement.  

Thanks in advance for your suggestions. 

Thanks

Arun