# decodeUnprotectedHeader

> **decodeUnprotectedHeader**(`value`): [`UnprotectedHeaderMap`](/reference/filoz/filecoin-encryption-envelope/namespaces/cose/type-aliases/unprotectedheadermap/)

Defined in: [packages/filecoin-encryption-envelope/src/cose/headers.ts:1125](https://github.com/FilOzone/synapse-sdk/blob/bc8a4b093324ccef9b407251fcf4e91823c6f599/packages/filecoin-encryption-envelope/src/cose/headers.ts#L1125)

Validate and return the content unprotected header.

Unknown non-critical parameters are allowed. `crit`, Partial IV, and IV
are rejected; cross-bucket label duplication is checked when the protected
header is decoded.

## Parameters

| Parameter | Type |
| ------ | ------ |
| `value` | [`CborValue`](/reference/filoz/filecoin-encryption-envelope/namespaces/cose/type-aliases/cborvalue/) |

## Returns

[`UnprotectedHeaderMap`](/reference/filoz/filecoin-encryption-envelope/namespaces/cose/type-aliases/unprotectedheadermap/)