fdroid-server/examples/public-read-only-s3-bucket-policy.json

{
    "Version":"2012-10-17",
    "Statement":[
        {"Sid":"AddPerm",
         "Effect":"Allow",
         "Principal":"*",
         "Action":"s3:GetObject",
         "Resource":"arn:aws:s3:::examplebucket/fdroid/*"
        }
    ]
}