Here is how you can get a list of all docker images and all tags for each docker image using curl.
Docker as of 1.1.2 hasn’t yet implemented searching in private registries, although docker-registry supports it.
To list all images in a registry:
curl https://your.docker.server/v1/search
To list all tags for a given image in a registry:
curl https://your.docker.server/v1/repositories/YOUR_IMAGE/tags
H/T to sontags: private registry search