added pkcs#8 script

scripts/reassemble_pkcs8.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: MIT-0
+
+set -e
+set +x
+
+raw_key=$1
+
+ASN1_PRIV_KEY_HEADER="302e0201010420"
+ASN1_SECP256K1_OID="a00706052b8104000a"
+OUT_FILE="priv_key.pkcs8"
+
+if [ -z "${raw_key}" ]; then
+  echo "Usage: $1 $0 <private_key>"
+  exit 1
+fi
+
+openssl pkcs8 -topk8 -outform DER -nocrypt -inform DER -in <(echo "${ASN1_PRIV_KEY_HEADER} ${raw_key} ${ASN1_SECP256K1_OID}" | xxd -r -p) -out ${OUT_FILE} &>/dev/null
+printf "private key successfully written to: %s\n" "${OUT_FILE}"
+
+#printf "asn1parse output:\n"
+#openssl asn1parse -in "${OUT_FILE}"