digest

package
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Published: Aug 26, 2021 License: Apache-2.0 Imports: 6 Imported by: 0

Documentation

Index

Constants

View Source
const (
	// DigestSha256EmptyTar is the canonical sha256 digest of empty data
	DigestSha256EmptyTar = "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
)

Variables

View Source
var (
	// ErrDigestInvalidFormat returned when digest format invalid.
	ErrDigestInvalidFormat = fmt.Errorf("invalid checksum digest format")

	// ErrDigestInvalidLength returned when digest has invalid length.
	ErrDigestInvalidLength = fmt.Errorf("invalid checksum digest length")

	// ErrDigestUnsupported returned when the digest algorithm is unsupported.
	ErrDigestUnsupported = fmt.Errorf("unsupported digest algorithm")
)
View Source
var DigestRegexp = regexp.MustCompile(`[a-zA-Z0-9-_+.]+:[a-fA-F0-9]+`)

DigestRegexp matches valid digest types.

View Source
var DigestRegexpAnchored = regexp.MustCompile(`^` + DigestRegexp.String() + `$`)

DigestRegexpAnchored matches valid digest types, anchored to the start and end of the match.

Functions

This section is empty.

Types

type Algorithm

type Algorithm string

Algorithm identifies and implementation of a digester by an identifier. Note the that this defines both the hash algorithm used and the string encoding.

const (
	SHA256 Algorithm = "sha256" // sha256 with hex encoding
	SHA384 Algorithm = "sha384" // sha384 with hex encoding
	SHA512 Algorithm = "sha512" // sha512 with hex encoding

	// Canonical is the primary digest algorithm used with the distribution
	// project. Other digests may be used but this one is the primary storage
	// digest.
	Canonical = SHA256
)

supported digest types

func (Algorithm) Available

func (a Algorithm) Available() bool

Available returns true if the digest type is available for use. If this returns false, New and Hash will return nil.

func (Algorithm) FromBytes

func (a Algorithm) FromBytes(p []byte) Digest

FromBytes digests the input and returns a Digest.

func (Algorithm) FromReader

func (a Algorithm) FromReader(rd io.Reader) (Digest, error)

FromReader returns the digest of the reader using the algorithm.

func (Algorithm) Hash

func (a Algorithm) Hash() hash.Hash

Hash returns a new hash as used by the algorithm. If not available, the method will panic. Check Algorithm.Available() before calling.

func (Algorithm) New

func (a Algorithm) New() Digester

New returns a new digester for the specified algorithm. If the algorithm does not have a digester implementation, nil will be returned. This can be checked by calling Available before calling New.

func (*Algorithm) Set

func (a *Algorithm) Set(value string) error

Set implemented to allow use of Algorithm as a command line flag.

func (Algorithm) Size

func (a Algorithm) Size() int

Size returns number of bytes returned by the hash.

func (Algorithm) String

func (a Algorithm) String() string

type Digest

type Digest string

Digest allows simple protection of hex formatted digest strings, prefixed by their algorithm. Strings of type Digest have some guarantee of being in the correct format and it provides quick access to the components of a digest string.

The following is an example of the contents of Digest types:

sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc

This allows to abstract the digest behind this type and work only in those terms.

func FromBytes

func FromBytes(p []byte) Digest

FromBytes digests the input and returns a Digest.

func FromReader

func FromReader(rd io.Reader) (Digest, error)

FromReader returns the most valid digest for the underlying content using the canonical digest algorithm.

func NewDigest

func NewDigest(alg Algorithm, h hash.Hash) Digest

NewDigest returns a Digest from alg and a hash.Hash object.

func NewDigestFromBytes

func NewDigestFromBytes(alg Algorithm, p []byte) Digest

NewDigestFromBytes returns a new digest from the byte contents of p. Typically, this can come from hash.Hash.Sum(...) or xxx.SumXXX(...) functions. This is also useful for rebuilding digests from binary serializations.

func NewDigestFromHex

func NewDigestFromHex(alg, hex string) Digest

NewDigestFromHex returns a Digest from alg and a the hex encoded digest.

func ParseDigest

func ParseDigest(s string) (Digest, error)

ParseDigest parses s and returns the validated digest object. An error will be returned if the format is invalid.

func (Digest) Algorithm

func (d Digest) Algorithm() Algorithm

Algorithm returns the algorithm portion of the digest. This will panic if the underlying digest is not in a valid format.

func (Digest) Hex

func (d Digest) Hex() string

Hex returns the hex digest portion of the digest. This will panic if the underlying digest is not in a valid format.

func (Digest) String

func (d Digest) String() string

func (Digest) Validate

func (d Digest) Validate() error

Validate checks that the contents of d is a valid digest, returning an error if not.

type Digester

type Digester interface {
	Hash() hash.Hash // provides direct access to underlying hash instance.
	Digest() Digest
}

Digester calculates the digest of written data. Writes should go directly to the return value of Hash, while calling Digest will return the current value of the digest.

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