Is there a way to verify an original author using encryption? I feel like the title explains the problem fairly well. Is is possible to use encryption to verify a document's original author? In my case, I have a doc that I want to release online. Is there a way I can make sure that anyone who finds the doc can verify that I was the original author who created it and not someone who just copied it?
Yesish, but only for cryptographic purposes within the scope of this forum.  My last bit will show that this isn't worth hill of beans legally, which also makes this question entirely off topic for practical purposes.

You could do this with a time stamping authority:-



All good fun for amateur cryptographers, but the problems start at step 1. A hash is performed of your original document.  Any good cryptographic hash (such as SHA-256) produces effectively unique outputs for any given input.  Even if the inputs only vary by one bit. So 

H("Tankobot") ≠ H("Tankobot ")

There's an extra space at the end of the second hash.  The little bits of the two hash outputs will be approximately 50% different. This is due to the avalanche effect inherent in all respectable hashes.

The negative consequence of this is that your plagiarised work will have to be word for word, character for character and bit for bit the same as your original.  It will have to be in the same human language and the same computer character set.  You'll have to retype and re format the suspect work to then perform the validity check to prove ownership. The slightest variation will result in different signed hashes.  

That's great for ASCII type text. If your document is graphical, there are sophisticated water marking techniques which are allegedly robust but have not really be field tested. Results for this are below, but I'm not sure how well noise robustness helps if the student redraws your document images:-



That's all wonderful and this answer stops here wrt cryptography.  In the real world, you're wasting your time.  You might as well post the document to yourself and pray. It might work if you catch a student cheating with homework and spank them.

In court, it's worthless.  This type of effort is termed Poor Man's Copyright.  Neither the courts or copyright offices of the UK nor US recognise these clever techniques.  The time stamp has zero evidentiary value in copyright terms.  Independent creation, derivative works and eye witness testimony of copying are some of the easy spanners that smash your system. This is an immense sector of law and I'm not qualified to provide advice. You'd better not be spanking any students as they can sue you if you can't prove they cheated in court.