s3_bucket_policy_with_encryption

 {
     "Version": "2012-10-17",
     "Id": "PutObjPolicy",
     "Statement": [
           {
                "Sid": "DenyIncorrectEncryptionHeader",
                "Effect": "Deny",
                "Principal": "*",
                "Action": "s3:PutObject",
                "Resource": "arn:aws:s3:::<bucket_name>/*",
                "Condition": {
                        "StringNotEquals": {
                               "s3:x-amz-server-side-encryption": "AES256"
                         }
                }
           },
           {
                "Sid": "DenyUnEncryptedObjectUploads",
                "Effect": "Deny",
                "Principal": "*",
                "Action": "s3:PutObject",
                "Resource": "arn:aws:s3:::<bucket_name>/*",
                "Condition": {
                        "Null": {
                               "s3:x-amz-server-side-encryption": true
                        }
               }
           }
     ]
 }