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Diffstat (limited to 'doc/source/admin/os_hash_algo.rst')
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diff --git a/doc/source/admin/os_hash_algo.rst b/doc/source/admin/os_hash_algo.rst new file mode 100644 index 000000000..04a8c1deb --- /dev/null +++ b/doc/source/admin/os_hash_algo.rst @@ -0,0 +1,38 @@ +.. + This work is licensed under a Creative Commons Attribution 3.0 Unported + License. + + http://creativecommons.org/licenses/by/3.0/legalcode + +========================================= +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. |