dd if=/dev/random of=keyfile count=1 bs=32
Endpoint is found in the bucket details via console.
aws --profile=b2 s3 \
cp <src> s3://<bucket>/ \
--sse-c=AES256 --sse-c-key=fileb://keyfile \
--endpoint-url=https://s3.us-west-001.backblazeb2.com/