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Content identity of a registry

Source: R/manifest.R
registry_digest.Rd

The digest of a registry's registry_manifest(). This is what identifies a declaration state: it is derived from the declaration rather than asserted alongside it, so it cannot be typed wrong, cannot go stale, and cannot claim that two different states are the same one. Provenance records it for every retrieved resource, so a cached file can always be traced to the exact declaration that resolved it.

Usage

registry_digest(registry)

Arguments

registry

A registry() object.

Value

A single string: an algorithm name, a colon, and lowercase hex.

Details

The value is self-describing, as in "sha256:3f9ac2...", so the algorithm can change later without changing the shape of anything that stores one.

A digest says whether two registries are the same. It does not say which is newer; created answers that. It also carries no authenticity: a digest travelling inside the file it describes is rewritten by anyone who rewrites the file. What stops a remote registry from redefining published bytes is the per-resource checksum comparison in resolve_resource(), which names the offending resource rather than reporting that something, somewhere, moved.

See also

registry_manifest() for the exact bytes hashed.

Examples

reg <- registry("demo", list(
  resource("example", "1.0",
           urls = "https://example.org/example-1.0.csv",
           sha256 = strrep("c", 64))
))
registry_digest(reg)