app: added helm tgz handle

app/storage/hasher.go

@@ -0,0 +1,32 @@
+package storage
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"hash"
+	"io"
+)
+
+type Hasher struct {
+	hasher hash.Hash
+}
+
+func NewHasher() *Hasher {
+	return &Hasher{
+		hasher: sha256.New(),
+	}
+}
+
+func (ha *Hasher) Writer() io.Writer {
+	return ha.hasher
+}
+
+func (ha *Hasher) Hex() string {
+	data := ha.hasher.Sum(nil)
+	res := hex.EncodeToString(data)
+	return "sha256:" + res
+}
+
+func (ha *Hasher) Verify(hash string) bool {
+	return hash == ha.Hex()
+}