# HEADER_CHUNK_SIZE

> `const` **HEADER\_CHUNK\_SIZE**: `-1` = `-1`

Defined in: [packages/filecoin-encryption-envelope/src/constants.ts:27](https://github.com/FilOzone/synapse-sdk/blob/4fe24ea1c76c9b1fa1489b7cdbb1cc279bd2576a/packages/filecoin-encryption-envelope/src/constants.ts#L27)

`chunk_size`, algorithm-specific label per RFC 9052 §3.1. Required for the
chunked scheme, must not appear when `alg` is [ALG\_AES\_256\_GCM](/reference/filoz/filecoin-encryption-envelope/variables/alg_aes_256_gcm/) (3) —
whole-object AEAD has no chunk layout.