4c850e7165
tarsum is not actually used by the registry. Remove support for it. Convert numerous uses in unit tests to SHA256. Update docs to remove mentions of tarsums (which were often inaccurate). Remove tarsum dependency. Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
42 lines
1.6 KiB
Go
42 lines
1.6 KiB
Go
// Package digest provides a generalized type to opaquely represent message
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// digests and their operations within the registry. The Digest type is
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// designed to serve as a flexible identifier in a content-addressable system.
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// More importantly, it provides tools and wrappers to work with
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// hash.Hash-based digests with little effort.
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//
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// Basics
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//
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// The format of a digest is simply a string with two parts, dubbed the
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// "algorithm" and the "digest", separated by a colon:
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//
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// <algorithm>:<digest>
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//
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// An example of a sha256 digest representation follows:
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//
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// sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc
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//
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// In this case, the string "sha256" is the algorithm and the hex bytes are
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// the "digest".
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//
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// Because the Digest type is simply a string, once a valid Digest is
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// obtained, comparisons are cheap, quick and simple to express with the
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// standard equality operator.
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//
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// Verification
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//
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// The main benefit of using the Digest type is simple verification against a
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// given digest. The Verifier interface, modeled after the stdlib hash.Hash
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// interface, provides a common write sink for digest verification. After
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// writing is complete, calling the Verifier.Verified method will indicate
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// whether or not the stream of bytes matches the target digest.
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//
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// Missing Features
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//
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// In addition to the above, we intend to add the following features to this
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// package:
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//
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// 1. A Digester type that supports write sink digest calculation.
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//
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// 2. Suspend and resume of ongoing digest calculations to support efficient digest verification in the registry.
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//
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package digest
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