# HEADER_KID

> `const` **HEADER\_KID**: `4` = `4`

Defined in: [packages/filecoin-encryption-envelope/src/cose/constants.ts:28](https://github.com/FilOzone/synapse-sdk/blob/9ad84d812e1dd635b76420a7d9388555a04f31b6/packages/filecoin-encryption-envelope/src/cose/constants.ts#L28)

`kid`, RFC 9052 §3.1. Recipients only; a byte string. Never a content header in this profile.