> Some of the existing tools, such as homomorphic encryption or secure enclaves have performance unsuited to scalable encrypted search, require proprietary hardware, or have uncertain security properties.

I don't think this is exactly homomorphic. I hope they put out a whitepaper so researchers can properly evaluate its security.

Nice catch, I was scanning for homomorphic encryption, but missed this. Have no idea how else they would implement this.

Homomorphic Encryption is available at large scale today for limited use cases.

See the MuchPIR project (https://github.com/ReverseControl/MuchPIR) which implements Information-Theoretic Private Information Retrieval (IT-PIR) in Postgresql; In addition to the demo there is a high performance version available for commercial use.

Its not Homomorphic but "structural encryption". Less useful than HE but faster.

Correct. It's not homomorphic encryption, but rather more like TDE (Transparent Data Encryption) except that MongoDB service isn't decrypting the data. This is essentially client-side encryption (at the driver) and without server-side decryption.

Faster has a usefulness all its own

Absolutely! FHE isn't practical for most applications.

Homomorphic encryption allows you to modify the encrypted data without decrypting it or even knowing the the content. I don’t think this is homomorphic encryption.

If they are able to do this without decrypting the data then I think you could describe this as a somewhat week encryption that exposes some data attributes as queryable. You could not implement this with strong encryption without at least decrypting for indexing.