60b6748c95
Vendored resumable sha256/sha512 library. Digest package new exports a resumable variant of the Digester. Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
80 lines
2.1 KiB
Go
80 lines
2.1 KiB
Go
package digest
|
|
|
|
import (
|
|
"crypto/sha256"
|
|
"fmt"
|
|
"hash"
|
|
|
|
"github.com/jlhawn/go-crypto" // For ResumableHash
|
|
_ "github.com/jlhawn/go-crypto/sha256" // For Resumable SHA256
|
|
_ "github.com/jlhawn/go-crypto/sha512" // For Resumable SHA384, SHA512
|
|
)
|
|
|
|
// Digester calculates the digest of written data. It is functionally
|
|
// equivalent to hash.Hash but provides methods for returning the Digest type
|
|
// rather than raw bytes.
|
|
type Digester struct {
|
|
alg string
|
|
hash.Hash
|
|
}
|
|
|
|
// NewDigester create a new Digester with the given hashing algorithm and instance
|
|
// of that algo's hasher.
|
|
func NewDigester(alg string, h hash.Hash) Digester {
|
|
return Digester{
|
|
alg: alg,
|
|
Hash: h,
|
|
}
|
|
}
|
|
|
|
// NewCanonicalDigester is a convenience function to create a new Digester with
|
|
// our default settings.
|
|
func NewCanonicalDigester() Digester {
|
|
return NewDigester("sha256", sha256.New())
|
|
}
|
|
|
|
// Digest returns the current digest for this digester.
|
|
func (d *Digester) Digest() Digest {
|
|
return NewDigest(d.alg, d.Hash)
|
|
}
|
|
|
|
// ResumableDigester is a digester that can export its internal state and be
|
|
// restored from saved state.
|
|
type ResumableDigester struct {
|
|
alg string
|
|
crypto.ResumableHash
|
|
}
|
|
|
|
var resumableHashAlgs = map[string]crypto.Hash{
|
|
"sha256": crypto.SHA256,
|
|
"sha384": crypto.SHA384,
|
|
"sha512": crypto.SHA512,
|
|
}
|
|
|
|
// NewResumableDigester creates a new ResumableDigester with the given hashing
|
|
// algorithm.
|
|
func NewResumableDigester(alg string) (ResumableDigester, error) {
|
|
hash, supported := resumableHashAlgs[alg]
|
|
if !supported {
|
|
return ResumableDigester{}, fmt.Errorf("unsupported resumable hash algorithm: %s", alg)
|
|
}
|
|
|
|
return ResumableDigester{
|
|
alg: alg,
|
|
ResumableHash: hash.New(),
|
|
}, nil
|
|
}
|
|
|
|
// NewCanonicalResumableDigester creates a ResumableDigester using the default
|
|
// digest algorithm.
|
|
func NewCanonicalResumableDigester() ResumableDigester {
|
|
return ResumableDigester{
|
|
alg: "sha256",
|
|
ResumableHash: crypto.SHA256.New(),
|
|
}
|
|
}
|
|
|
|
// Digest returns the current digest for this resumable digester.
|
|
func (d ResumableDigester) Digest() Digest {
|
|
return NewDigest(d.alg, d.ResumableHash)
|
|
}
|