Generated seal unseal store and read scripts for TPM.

tpm-unseal-password.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+#
+# Retrieve a password previously sealed into the TPM 2.0 with
+# tpm-seal-password.sh. The TPM only releases the password if the current
+# PCR values match those recorded when it was sealed.
+# Requires: tpm2-tools, access to /dev/tpmrm0 (tss group or root).
+
+set -euo pipefail
+
+HANDLE="0x81010001"
+PCR_LIST="sha256:7"
+
+usage() {
+	cat <<-EOF
+	Usage: $(basename "$0") [-H handle] [-l pcr-list]
+
+	  -H handle     Persistent TPM handle the password was sealed at
+	                (default: ${HANDLE})
+	  -l pcr-list   PCR bank and indices the password was bound to at
+	                seal time (default: ${PCR_LIST})
+	EOF
+}
+
+while getopts "H:l:h" opt; do
+	case "$opt" in
+	H) HANDLE="$OPTARG" ;;
+	l) PCR_LIST="$OPTARG" ;;
+	h) usage; exit 0 ;;
+	*) usage; exit 1 ;;
+	esac
+done
+
+command -v tpm2_unseal >/dev/null || {
+	echo "tpm2-tools is required (apt install tpm2-tools)" >&2
+	exit 1
+}
+
+if ! tpm2_readpublic -c "$HANDLE" >/dev/null 2>&1; then
+	echo "No sealed object found at handle ${HANDLE}" >&2
+	exit 1
+fi
+
+tpm2_unseal -c "$HANDLE" -p "pcr:${PCR_LIST}"