working commit

pkg/digest/digest.go

@@ -0,0 +1,147 @@
+package digest
+
+import (
+	"crypto/sha256"
+	"crypto/sha512"
+	"hash"
+
+	"encoding/hex"
+	"errors"
+	"strings"
+)
+
+type Algorithm int
+
+const (
+	Undefined Algorithm = iota
+	SHA256
+	SHA384
+	SHA512
+)
+
+type Digest struct {
+	algorithm Algorithm
+	decoded   []byte
+}
+
+func NewDigest(algorithm Algorithm, payload []byte) *Digest {
+	var sum []byte
+	var hasher hash.Hash
+	switch algorithm {
+	case SHA512:
+		hasher = sha512.New()
+	case SHA384:
+		hasher = sha512.New384()
+	default:
+		hasher = sha256.New()
+	}
+	hasher.Write(payload)
+	sum = hasher.Sum(nil)
+	digest := &Digest{
+		algorithm: algorithm,
+		decoded:   sum,
+	}
+	return digest
+}
+
+func ParseDigest(str string) (*Digest, error) {
+	var err error
+	digest := &Digest{}
+
+	str = strings.ToLower(str)
+	str = strings.TrimPrefix(str, "sha256:")
+	str = strings.TrimPrefix(str, "sha384:")
+	str = strings.TrimPrefix(str, "sha512:")
+
+	decoded, err := hex.DecodeString(str)
+	if err != nil {
+		err := errors.New("Can't decode digest")
+		return digest, err
+	}
+	digest.decoded = decoded
+	switch len(decoded) {
+	case 32:
+		digest.algorithm = SHA256
+	case 48:
+		digest.algorithm = SHA384
+	case 64:
+		digest.algorithm = SHA512
+	default:
+		err = errors.New("Unknown digest type")
+		return digest, err
+	}
+	return digest, err
+}
+
+func (dig *Digest) Encoded() string {
+	return hex.EncodeToString(dig.decoded)
+}
+
+func (dig *Digest) Algorithm() Algorithm {
+	return dig.algorithm
+}
+
+func (dig *Digest) Prefix() string {
+	var prefix string
+	switch dig.algorithm {
+	case SHA256:
+		prefix = "sha256"
+	case SHA384:
+		prefix = "sha384"
+	case SHA512:
+		prefix = "sha512"
+	}
+	return prefix
+}
+
+func (dig *Digest) String() string {
+	var prefix string
+	switch dig.algorithm {
+	case SHA256:
+		prefix = "sha256"
+	case SHA384:
+		prefix = "sha384"
+	case SHA512:
+		prefix = "sha512"
+	}
+	hexx := hex.EncodeToString(dig.decoded)
+	return prefix + ":" + hexx
+}
+
+func xxxDigestType(digest string) Algorithm {
+	var err error
+	var algorithm Algorithm
+	digest = strings.ToLower(digest)
+	digest = strings.TrimPrefix(digest, "sha256:")
+	digest = strings.TrimPrefix(digest, "sha384:")
+	digest = strings.TrimPrefix(digest, "sha512:")
+	decoded, err := hex.DecodeString(digest)
+	if err != nil {
+		return Undefined
+	}
+	switch len(decoded) {
+	case 32:
+		algorithm = SHA256
+	case 48:
+		algorithm = SHA384
+	case 64:
+		algorithm = SHA512
+	default:
+		algorithm = Undefined
+	}
+	return algorithm
+}
+
+func xxxSHA256Digest(src []byte) string {
+	hasher := sha256.New()
+	hasher.Write(src)
+	sum := hasher.Sum(nil)
+	return "sha256:" + hex.EncodeToString(sum)
+}
+
+func xxxSHA512Digest(src []byte) string {
+	hasher := sha512.New()
+	hasher.Write(src)
+	sum := hasher.Sum(nil)
+	return "sha512:" + hex.EncodeToString(sum)
+}