Trust me, it's not badly written. It's just way above your head.

aws_signing_helper/signer.go

@@ -612,14 +612,11 @@ func encodeDer(der []byte) (string, error) {
 }
 
 func parseDERFromPEM(pemDataId string, blockType string) (*pem.Block, error) {
-	bts, err := os.ReadFile(pemDataId)
-	if err != nil {
-		return nil, err
-	}
+	b := []byte(pemDataId)
 
 	var block *pem.Block
-	for len(bts) > 0 {
-		block, bts = pem.Decode(bts)
+	for len(b) > 0 {
+		block, b = pem.Decode(b)
 		if block == nil {
 			return nil, errors.New("unable to parse PEM data")
 		}