Correct answer - "SSE-C" : Amazon S3 will reject any requests made over http when using SSE-C.
For security considerations, we recommend you consider any key you send erroneously using http
to be compromised.
"SSE-KMS" - Not mandatory to use HTTPS.
"Client Side Encryption" - Client-side encryption is the act of encrypting data before sending it
to Amazon S3. It is not mandatory to use HTTPS for this.
"SSE-S3" - Not mandatory to use HTTPS. Amazon S3 encrypts your data at the object level as it
writes it to disks in its data centers