containerd/vendor/github.com/docker/distribution/digest/doc.go
Phil Estes dd9309c15e
Add vendoring to containerd master
Initial vendor list validated with empty $GOPATH
and only master checked out; followed by `make`
and verified that all binaries build properly.
Updates require github.com/LK4D4/vndr tool.

Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>
2017-01-11 16:59:06 -05:00

42 lines
1.6 KiB
Go

// Package digest provides a generalized type to opaquely represent message
// digests and their operations within the registry. The Digest type is
// designed to serve as a flexible identifier in a content-addressable system.
// More importantly, it provides tools and wrappers to work with
// hash.Hash-based digests with little effort.
//
// Basics
//
// The format of a digest is simply a string with two parts, dubbed the
// "algorithm" and the "digest", separated by a colon:
//
// <algorithm>:<digest>
//
// An example of a sha256 digest representation follows:
//
// sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc
//
// In this case, the string "sha256" is the algorithm and the hex bytes are
// the "digest".
//
// Because the Digest type is simply a string, once a valid Digest is
// obtained, comparisons are cheap, quick and simple to express with the
// standard equality operator.
//
// Verification
//
// The main benefit of using the Digest type is simple verification against a
// given digest. The Verifier interface, modeled after the stdlib hash.Hash
// interface, provides a common write sink for digest verification. After
// writing is complete, calling the Verifier.Verified method will indicate
// whether or not the stream of bytes matches the target digest.
//
// Missing Features
//
// In addition to the above, we intend to add the following features to this
// package:
//
// 1. A Digester type that supports write sink digest calculation.
//
// 2. Suspend and resume of ongoing digest calculations to support efficient digest verification in the registry.
//
package digest