Considering that you don't know whether you can be sure that you've used a secure implementation, then the answer is a resounding, NO! It is not, by your own admission, 'safe' to publish any data that needs to remain secure in a publicly available setting.

Once you can answer yes to:

<snip> How can you be sure you've used a secure implementation? No idea </snip>

Then you will be able to ascertain for yourself whether your encrypted data, placed in a publicly available location, is "Safe Enough", "Secure Enough" for your needs.

It would be naive to assume that any data placed somewhere, encrypted or not, is stored with a completely invulnerable method.

That having been said, one must rise to the occasion of determining how secure something needs to be, and then availing oneself of the means to achieve that level of security.

I hope that helps, but in reality, there really isn't a cut and dried YES|NO answer - only relative levels of reasonable assurance in securing your data and communications.