Honest question, who actually holds voter information in a state. You have to register in the county that you live in, so I would think the bulk of the info would be there. I thought (possibly mistakenly) that the state election board enforced the rules and laws governing elections, and just a list of registered voters and party affiliation.
The Oklahoma State Election Board is in charge, and delegates registration and other duties to County Election Boards. The data they collect is public record by law - full name, address, date of birth, party affiliations, sex, registration date, and elections that the person has voted in. Here is a database you, or the Orwellian named Presidential Advisory Commission on Election Integrity can go and look it up (this particular database has since stopped publishing when people voted, but the info is publicly available and all political parties pay someone to pull and sort it. That's how they make targeted mailing list and door knocking campaigns):
http://www.oklahomadata.com/The Election Board:
https://www.ok.gov/elections/About_Us/index.htmlDon't feel bad about not knowing, the blue ribbon panel didn't know either. They sent the request to the Secretary of State, which is not involved.
http://newsok.com/article/5554766