// sealed 'ObjectKey' can be unsealed and the object can be decrypted.
//
// ## SSE-C
//
// SSE-C computes the key-encryption-key from the client-provided key, an
// initialization vector (IV) and the bucket/object path.
//
//  1. Encrypt:
//     Input: ClientKey, bucket, object, metadata, object_data
//     -              IV := Random({0,1}²⁵⁶)
//     -       ObjectKey := SHA256(ClientKey || Random({0,1}²⁵⁶))