This would be similar to what is done with the S3 backend .
However, the Images API does not support extensions, so this is not a valid approach.
Another alternative to using the Glance properties to store and retrieve the signature metadata would be to use the CMS (cryptographic message syntax) format as defined in RFC 5652 Section 5.
An alternative to using the existing MD5 hash algorithm is to create a separate configurable hash for use with verifying/creating the signature.
However, creating a separate hash negatively affects the performance, without providing much benefit.
This access would enable Glance to modify the image and create a new signature without the user’s knowledge.
Using asymmetric keys enables Glance to verify the signature without giving Glance the power to modify the image and signature.There is no method for users to verify that a previously uploaded image has not been modified.An image could potentially be modified in transit (such as when it is uploaded to Glance or transferred to Nova) or Glance itself could be untrusted and modify images without a user’s knowledge.However, the size for this would be variable, and could not use the existing Glance properties, which would require API modifications.For the initial implementation, Glance properties will be used, with the plan to migrate to using CMS in a future implementation as the need for increased flexibility arises.These are provided when the image is created, and are accessible when the image is uploaded.