Removing unused hex_bytes.go

Signed-off-by: Diogo Monica <diogo@docker.com>

signer/keys/hex_bytes.go

@@ -1,36 +0,0 @@
-package keys
-
-import (
-	"encoding/hex"
-	"errors"
-)
-
-// HexBytes represents hexadecimal bytes
-type HexBytes []byte
-
-// UnmarshalJSON allows the representation in JSON of hexbytes
-func (b *HexBytes) UnmarshalJSON(data []byte) error {
-	if len(data) < 2 || len(data)%2 != 0 || data[0] != '"' || data[len(data)-1] != '"' {
-		return errors.New("tuf: invalid JSON hex bytes")
-	}
-	res := make([]byte, hex.DecodedLen(len(data)-2))
-	_, err := hex.Decode(res, data[1:len(data)-1])
-	if err != nil {
-		return err
-	}
-	*b = res
-	return nil
-}
-
-// MarshalJSON allows the representation in JSON of hexbytes
-func (b HexBytes) MarshalJSON() ([]byte, error) {
-	res := make([]byte, hex.EncodedLen(len(b))+2)
-	res[0] = '"'
-	res[len(res)-1] = '"'
-	hex.Encode(res[1:], b)
-	return res, nil
-}
-
-func (b HexBytes) String() string {
-	return hex.EncodeToString(b)
-}