aes – Which encryption technique should be adopted to keep the search functionalities?

I am in exactly the same situation as described in this post. I must be able to encrypt data from a client workstation then send it to an untrusted server (encrypted at rest), then decrypt it only on the same client workstation. However, the client must be able to continue to do “encrypted” searches based on the cypher text.

AES CBC seems to need a unique IV for each encryption, so I can’t use this technique. And all others, CGM, … and even the asymmetric RSA encryption have the same behavior with a padding which means that the cypher text is never the same for the same plain text …

It seems that only AES ECB can produce the same cypher text. The important point in my case is that the data that I have to encrypt is all in the format string max 1000 char and also that I have to protect this data from the hoster (at rest), there is no risk the In Transit and the data are not exhibited on the internet. I don’t know if I can rely on ECB…

So I ask the question again because 5 years have passed since that post, there may be other options? Can you advise me which technique to use being quite secure and ensuring the non-brute forcing and with which I can continue to search (on cypher text). Can I use AES CBC with the same IV? Can I use AES ECB (256)? Others?