entropy: a simple way to add and save random entropy

packages/sysutils/entropy/package.mk

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+################################################################################
+#      This file is part of OpenELEC - http://www.openelec.tv
+#      Copyright (C) 2009-2016 Stephan Raue (stephan@openelec.tv)
+#
+#  OpenELEC is free software: you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation, either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  OpenELEC is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with OpenELEC.  If not, see <http://www.gnu.org/licenses/>.
+################################################################################
+
+PKG_NAME="entropy"
+PKG_VERSION="0"
+PKG_REV="1"
+PKG_ARCH="any"
+PKG_LICENSE="GPL"
+PKG_SITE=""
+PKG_URL=""
+PKG_DEPENDS_TARGET="toolchain"
+PKG_PRIORITY="optional"
+PKG_SECTION="system"
+PKG_SHORTDESC="A simple way to add entropy at boot"
+PKG_LONGDESC="A simple way to add entropy at boot"
+
+PKG_IS_ADDON="no"
+PKG_AUTORECONF="no"
+
+make_target(){
+  :
+}
+
+makeinstall_target() {
+  mkdir -p $INSTALL/usr/lib/entropy
+    cp add-entropy $INSTALL/usr/lib/entropy
+    cp add-random-at-shutdown $INSTALL/usr/lib/entropy
+
+  chmod +x $INSTALL/usr/lib/entropy/*
+}
+
+post_install() {
+  enable_service add-entropy.service
+  enable_service add-random-at-shutdown.service
+}

packages/sysutils/entropy/sources/add-entropy

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+#!/usr/bin/python
+
+import os
+import struct
+
+RNDADDENTROPY = 0x40085203
+import fcntl
+
+def add_entropy(fd, data):
+    add = struct.pack('ii', len(data)*8, len(data)) + data
+    fcntl.ioctl(fd, RNDADDENTROPY, add)
+
+if not os.path.isfile("/storage/.cache/random.data"):
+    os.system("dd if=/dev/urandom of=/storage/.cache/random.data count=4 >/dev/null")
+
+cache=os.open("/storage/.cache/random.data", os.O_RDONLY)
+
+rnd=os.open("/dev/random", os.O_RDWR)
+
+while True:
+    data=os.read(cache, 512)
+    if len(data) == 0:
+        break
+    add_entropy(rnd, data)

packages/sysutils/entropy/sources/add-random-at-shutdown

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+#!/bin/sh
+dd if=/dev/urandom of=/storage/.cache/random.data count=4

packages/sysutils/entropy/system.d/add-entropy.service

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+[Unit]
+Description=Add random entropy from file
+DefaultDependencies=no
+After=systemd-tmpfiles-setup.service
+Before=systemd-udevd.service
+
+[Service]
+Type=oneshot
+ExecStart=/usr/lib/entropy/add-entropy
+RemainAfterExit=yes
+
+[Install]
+WantedBy=basic.target

packages/sysutils/entropy/system.d/add-random-at-shutdown.service

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+[Unit]
+Description=Save random entropy at shutdown
+DefaultDependencies=no
+Before=systemd-poweroff.service systemd-reboot.service systemd-halt.service
+
+[Service]
+Type=oneshot
+ExecStart=/usr/lib/entropy/add-random-at-shutdown
+RemainAfterExit=yes
+
+[Install]
+WantedBy=poweroff.target reboot.target halt.target