68 lines
3.2 KiB
Diff
68 lines
3.2 KiB
Diff
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From 98047e08d02b91f632ec8554fc02af05069216dd Mon Sep 17 00:00:00 2001
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From: Moritz Maxeiner <moritz@ucworks.org>
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Date: Mon, 13 Jul 2015 17:53:29 +0200
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Subject: [PATCH] crypt-gpg: Add README describing the procedure of moving from
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password-only gpg keyfile to password/smartcard gpg keyfile
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---
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modules.d/91crypt-gpg/README | 50 ++++++++++++++++++++++++++++++++++++++++++++
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1 file changed, 50 insertions(+)
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create mode 100644 modules.d/91crypt-gpg/README
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diff --git a/modules.d/91crypt-gpg/README b/modules.d/91crypt-gpg/README
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new file mode 100644
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index 00000000..be6df55a
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--- /dev/null
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+++ b/modules.d/91crypt-gpg/README
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@@ -0,0 +1,50 @@
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+# Directions for changing a system from password-based gpg keyfile
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+# to smartcard-based gpg keyfile
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+
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+# Be sure that you meet the following requirements:
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+# 1. GnuPG >= 2.1 installed with
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+# * Smartcard support enabled (scdaemon must be built)
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+# * Direct CCID access built into scdaemon
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+# 2. A password-based gpg keyfile ${KEYFILE} (e.g. "keyfile.gpg"):
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+# That is, a file containing the slot key for LUKS, which
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+# has been encrypted symmetrically with GnuPG using
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+# a password.
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+# 3. Your public OpenPGP identity ${RECIPIENT} (e.g. "3A696356")
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+# 4. An OpenPGP smartcard holding the decryption key associated
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+# with your public identity
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+# 5. A CCID smartcard reader
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+
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+# Notes: Requirement 4. and 5. can of course be one device, e.g.
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+# a USB token with an integrated OpenPGP smartcard
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+
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+# Make a backup of your keyfile (assuming it lies on the boot partition)
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+$ cp /boot/${KEYFILE} /safe/place/keyfile.bak.gpg
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+
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+# Change your keyfile from purely password-based to both
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+# password-based and key-based (you can then decrypt the keyfile
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+# with either method). As an example aes256 is chosen, the cipher
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+# is not important to this guide, but do note that your kernel
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+# must support it at boot time (be it built into the kernel image
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+# or loaded as a module from the initramfs).
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+$ cat /safe/place/keyfile.bak.gpg | gpg -d | gpg --encrypt --recipient ${RECIPIENT} --cipher-algo aes256 --armor -c > /safe/place/keyfile_sc.gpg
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+
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+# Verify that you can decrypt your new keyfile both with the password
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+# and your smartcard.
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+# (with smartcard inserted, you should be prompted for your PIN, unless
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+# you already did so and have not yet timed out)
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+$ gpg -d /safe/place/keyfile_sc.gpg
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+# (with smartcard disconnected, you should be prompted for your password)
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+$ gpg -d /safe/place/keyfile_sc.gpg
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+
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+# After verification, replace your old keyfile with your new one
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+$ su -c 'cp /safe/place/keyfile_sc.gpg /boot/${KEYFILE}'
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+
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+# Export your public key to where crypt-gpg can find it
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+$ gpg --armor --export-options export-minimal --export ${RECIPIENT} > /safe/place/crypt-public-key.gpg
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+$ su -c 'cp /safe/place/crypt-public-key.gpg /etc/dracut.conf.d/crypt-public-key.gpg'
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+
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+# Rebuild your initramfs as usual
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+# When booting with any of the requirements not met, crypt-gpg will default to password-based keyfile unlocking.
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+# If all requirements are met and smartcard support is not disabled by setting the kernel option "rd.luks.smartcard=0"
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+# crypt-gpg will try find and use a connected OpenPGP smartcard by prompting you for the PIN and then
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+# unlocking the gpg keyfile with the smartcard.
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