digest

package
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Published: Mar 6, 2019 License: Apache-2.0 Imports: 5 Imported by: 0

Documentation

Index

Constants

This section is empty.

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) 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) 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 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 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) 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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