NDAs, privacy and identification

Forgive me if this is a dry topic but I’ve recently been involved with an SD. Great guy who comes from wealth, business and assets, and because of how much is at stake, we’ve discussed signing an NDA as part of our engagement (to protect privacy, etc).

He then suggested a photograph of my drivers license would suffice. Has anyone else done this?

I understand this is a new arrangement and trust needs to be deepened over time, but I also want to reassure him that his personal life is safe as he has a lot more to lose than I do.

Any advice would be appreciated.