I definitely think posting a resume or CV online is worthwhile. Some recruiters or employers do browse online CVs routinely and if yours isn’t there, how do you expect them to see it?
As for it not being secure, enclose all the information you usually would, except your home address and telephone number. Include an email address, but it is a good idea to create a new one for the specific purpose of new employers contacting you. This way, if you start receiving spam, you aren’t losing a personal email account and you can close that one and make a new one.