# HEADER_IV

> `const` **HEADER\_IV**: `5` = `5`

Defined in: [packages/filecoin-encryption-envelope/src/constants.ts:18](https://github.com/FilOzone/synapse-sdk/blob/4fe24ea1c76c9b1fa1489b7cdbb1cc279bd2576a/packages/filecoin-encryption-envelope/src/constants.ts#L18)

`iv`, RFC 9052 §3.1. Unprotected: 12-byte nonce (scheme 1) or 7-byte base nonce (chunked).