Storing biometric data on blockchain

I’m currently working on a side project on decentralised and private identity. I’ve currently figured out a way of storing personal details (name, DoB, nationality, degree reports etc) on chain without revealing the data and verifiable using zero knowledge proofs.

Now I’m trying to figure out ways to store biometric data like fingerprints or face data on chain. This has to be both private and verifiable.

My problems:

1. Hashing: I can’t store the hash of biometric data because it’ll be slightly different every time you scan it. This will greatly alter the hash and would be impossible to verify.

2. Key encryption: This also has the same problem as hashing. The data will be slightly different every time and it can’t be verified.

3. Homomorphic encryption: This seems to be the most viable option. If I can compute the cosine difference between 2 different encrypted data, it’ll be helpful. But it’s computationally expensive and will result in a lot of noise.

Help a brother out if you know any way to do it the right way.

And if you are interested in building fun projects like this, hmu.