# Secure Hash Algorithm Support (Multihash)

The Secure Hash Algorithm feature supplements the current ‘checksum’ image property with a self-describing secure hash.

The self-description consists of two new image properties:

`os_hash_algo`

  Contains the name of the secure hash algorithm used to generate the value on the image

`os_hash_value`

  The hexdigest computed by applying the secure hash algorithm named in the `os_hash_algo` property to the image data

## Hash Algorithm Configuration

`os_hash_algo` will be populated by the value of the configuration option `hashing_algorithm` in the `glance.conf` file. The `os_hash_value` value will be populated by the hexdigest computed when the algorithm is applied to the uploaded or imported image data.

These are read-only image properties and are not user-modifiable.

The default secure hash algorithm is SHA-512. It should be suitable for most applications.

The multihash is computed only for new images. There is no provision for computing the multihash for existing images.

this page last updated: 2026-08-19 03:42:39

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