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NIIBE Yutaka
2016-07-08 12:55:09 +09:00
parent 2647797348
commit 5edcf32bb7
3 changed files with 242 additions and 10 deletions
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244
doc/generating-key.rst
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@@ -1,9 +1,11 @@
============================
Generating 2048-bit RSA keys
============================
====================
Generating key pairs
====================
In this section, we describe how to generate 2048-bit RSA keys.
You would like to use newer ECC keys instead of RSA keys. It is also described.
Key length of RSA
=================
@@ -18,8 +20,7 @@ advises that 2048-bit keys should be viable until 2030.
As of 2016, GnuPG's default for generating RSA key is 2048-bit.
Some people have preference on RSA 4096-bit keys, considering
"longer is better".
Some people have preference on RSA 4096-bit keys, considering "longer is better".
However, "longer is better" is not always true. When it's long, it
requires more computational resource, memory, and storage. Further,
@@ -37,9 +38,11 @@ considering device computation power and host software constraints.
Thus, the key size is 2048-bit in the examples below.
When/If your environment allows use of newer ECC keys, newer ECC keys are recommended.
Generating keys on host PC
==========================
Generating RSA keys on host PC
==============================
Here is the example session to generate main key and a subkey for encryption.
@@ -255,3 +258,230 @@ From the backup,
we can recover privet key by invoking GnuPG with ``--import`` option. ::
$ gpg --import <YOUR-SECRET>.asc
Generating ECC keys on host PC
==============================
Here is an example session log to create newer ECC keys. You need
libgcrypt 1.7 or newer and GnuPG 2.1.8 or newer.
Next, we invoke gpg frontend with ``--expert`` and ``--full-gen-key`` option. ::
$ gpg --expert --full-gen-key
gpg (GnuPG) 2.1.13; Copyright (C) 2016 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Then, we input ``9`` to select ECC primary key and ECC encryption subkey. ::
Please select what kind of key you want:
(1) RSA and RSA (default)
(2) DSA and Elgamal
(3) DSA (sign only)
(4) RSA (sign only)
(7) DSA (set your own capabilities)
(8) RSA (set your own capabilities)
(9) ECC and ECC
(10) ECC (sign only)
(11) ECC (set your own capabilities)
Your selection? 9
Next is the important selection. We input ``1`` to select "Curve25519". ::
Please select which elliptic curve you want:
(1) Curve 25519
(2) NIST P-256
(3) NIST P-384
(4) NIST P-521
(5) Brainpool P-256
(6) Brainpool P-384
(7) Brainpool P-512
(8) secp256k1
Your selection? 1
You may see WARNING (it depends on version of GnuPG) and may been asked. Since it is what you want, please answer with 'y'. ::
gpg: WARNING: Curve25519 is not yet part of the OpenPGP standard.
Use this curve anyway? (y/N) y
It asks about expiration of key. ::
Please specify how long the key should be valid.
0 = key does not expire
<n> = key expires in n days
<n>w = key expires in n weeks
<n>m = key expires in n months
<n>y = key expires in n years
Key is valid for? (0)
Key does not expire at all
Is this correct? (y/N) y
Then, it asks about a user ID. ::
GnuPG needs to construct a user ID to identify your key.
Real name: Kunisada Chuji
Email address: chuji@gniibe.org
Comment:
You selected this USER-ID:
"Kunisada Chuji <chuji@gniibe.org>"
Lastly, it asks confirmation. ::
Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
Then, it goes like this. ::
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
It asks the passphrase for keys by pop-up window, and then, finishes. ::
gpg: key 17174C1A7C406DB5 marked as ultimately trusted
gpg: revocation certificate stored as '/home/gniibe.gnupg/openpgp-revocs.d/1719874a4fe5a1d8c465277d5a1bb27e3000f4ff.rev'
public and secret key created and signed.
gpg: checking the trustdb
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 6 signed: 67 trust: 0-, 0q, 0n, 0m, 0f, 6u
gpg: depth: 1 valid: 67 signed: 40 trust: 67-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2016-10-05
pub ed25519 2016-07-08
F478770235B60A230BE78005006A236C292C31D7
uid [ultimate] Kunisada Chuji <chuji@gniibe.org>
sub cv25519 2016-07-08
$
We have the primary key with ed25519, and encryption subkey with cv25519.
Next, we add authentication subkey which can be used with OpenSSH.
We invoke gpg frontend with ``--edit-key`` and the key ID. ::
$ gpg2 --expert --edit-key 17174C1A7C406DB5
gpg (GnuPG) 2.1.13; Copyright (C) 2016 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Secret key is available.
sec ed25519/17174C1A7C406DB5
created: 2016-07-08 expires: never usage: SC
trust: ultimate validity: ultimate
ssb cv25519/37A03183DF7B31B1
created: 2016-07-08 expires: never usage: E
[ultimate] (1). Kunisada Chuji <chuji@gniibe.org>
We invoke ``addkey`` subcommand. ::
gpg> addkey
It asks a kind of key, we input ``11`` to select ECC for authentication. ::
Please select what kind of key you want:
(3) DSA (sign only)
(4) RSA (sign only)
(5) Elgamal (encrypt only)
(6) RSA (encrypt only)
(7) DSA (set your own capabilities)
(8) RSA (set your own capabilities)
(10) ECC (sign only)
(11) ECC (set your own capabilities)
(12) ECC (encrypt only)
(13) Existing key
Your selection? 11
and then, we specify "Authenticate" capability. ::
Possible actions for a ECDSA/EdDSA key: Sign Authenticate
Current allowed actions: Sign
(S) Toggle the sign capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? a
Possible actions for a ECDSA/EdDSA key: Sign Authenticate
Current allowed actions: Sign Authenticate
(S) Toggle the sign capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? s
Possible actions for a ECDSA/EdDSA key: Sign Authenticate
Current allowed actions: Authenticate
(S) Toggle the sign capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? q
Then, it asks which curve. We input ``1`` for "Curve25519". ::
Please select which elliptic curve you want:
(1) Curve 25519
(2) NIST P-256
(3) NIST P-384
(4) NIST P-521
(5) Brainpool P-256
(6) Brainpool P-384
(7) Brainpool P-512
(8) secp256k1
Your selection? 1
It may ask confirmation with WARNING (depends on version). We say ``y``. ::
gpg: WARNING: Curve25519 is not yet part of the OpenPGP standard.
Use this curve anyway? (y/N) y
It asks expiration of the key. ::
Please specify how long the key should be valid.
0 = key does not expire
<n> = key expires in n days
<n>w = key expires in n weeks
<n>m = key expires in n months
<n>y = key expires in n years
Key is valid for? (0)
Key does not expire at all
Is this correct? (y/N) y
And the confirmation. ::
Really create? (y/N) y
It goes. ::
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
It asks the passphrase. And done. ::
sec ed25519/17174C1A7C406DB5
created: 2016-09-08 expires: never usage: SC
trust: ultimate validity: ultimate
ssb cv25519/37A03183DF7B31B1
created: 2016-09-08 expires: never usage: E
ssb ed25519/4AD7D2428679DF5F
created: 2016-09-08 expires: never usage: A
[ultimate] (1). Kunisada Chuji <chuji@gniibe.org>
We type ``save`` to exit form gpg. ::
gpg> save
$

2
doc/index.rst
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@@ -20,7 +20,7 @@ Contents:
udev-rules.rst
gnuk-token-initial-configuration.rst
gnuk-personalization.rst
generating-2048-RSA-key.rst
generating-key.rst
gnuk-keytocard.rst
gnuk-keytocard-noremoval.rst
gnuk-passphrase-setting.rst

6
doc/intro.rst
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@@ -9,6 +9,8 @@ Gnuk is an implementation of USB cryptographic token for GNU Privacy
Guard. Gnuk supports OpenPGP card protocol version 2, and it runs on
STM32F103 processor.
This document explains about Gnuk 1.2, which comes with ECC algorithm.
Cryptographic token and feature of Gnuk
---------------------------------------
@@ -51,7 +53,7 @@ Host prerequisites for using Gnuk Token
* [Optional] SSH: openssh
* [optional] Web: scute, firefox
* [experimental] Web: scute, firefox
Usages
@@ -60,4 +62,4 @@ Usages
* Sign with GnuPG
* Decrypt with GnuPG
* Use with OpenSSH through gpg-agent (as ssh-agent)
* Use with Firefox through Scute for X.509 client certificate authentication
* [experimental] Use with Firefox through Scute for X.509 client certificate authentication