1IPSEC_RSASIGKEY(8) Executable programs IPSEC_RSASIGKEY(8)
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6 ipsec_rsasigkey - generate RSA signature key
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9 ipsec rsasigkey [--verbose] [--seeddev device] [--seed numbits]
10 [--configdir nssdbdir] [--password nsspassword]
11 [--hostname hostname] [nbits]
12
14 Rsasigkey generates an RSA public/private key pair, suitable for
15 digital signatures, of (exactly) nbits bits (that is, two primes each
16 of exactly nbits/2 bits, and related numbers) and emits it on standard
17 output as ASCII (mostly hex) data. nbits must be a multiple of 16.
18 The public exponent is forced to the value 3, which has important speed
20 advantages for signature checking. Beware that the resulting keys have
21 known weaknesses as encryption keys and should not be used for that
22 purpose.
23 The --verbose option makes rsasigkey give a running commentary on
25 standard error. By default, it works in silence until it is ready to
26 generate output.
27 The --seeddev option specifies a source for random bits used to seed
29 the crypto library´s RNG. The default is /dev/random (see random(4)).
30 FreeS/WAN and Openswan without NSS support used this option to specify
31 the random source used to directly create keys. Libreswan only uses it
32 to seed the NSS crypto libraries RNG. Under Linux with hardware random
33 support, special devices might show up as /dev/*rng* devices. However,
34 these should never be accessed directly using this option, as hardware
35 failures could lead to extremely non-random values (streams of zeroes
36 have been observed in the wild)
37 The --seedbits option specifies how many seed bits are pulled from the
39 random device to seed the NSS PRNG. The default of 480bit comes from
40 FIPS requirements. Seed bits are rounded up to a multiple of 8.
41 The use of a different random device or a reduction of seedbits from
43 the default value is prevented when the system is running in FIPS mode.
44 The --configdir option specifies the nss configuration directory to
46 use. This is the directory where the NSS certificate, key and security
47 modules databases reside. The default value is /etc/ipsec.d.
48 The --password option specifies the nss cryptographic module
50 authentication password if the NSS module has been configured to
51 require it. A password is required by hardware tokens and also by the
52 internal software token module when configured to run in FIPS mode. If
53 the argument is configdir/nsspassword, the password comes from that
54 file; otherwise argument is the password.
55 The --hostname option specifies what host name to use in the first line
57 of the output (see below); the default is what gethostname(2) returns.
58 The output format looks like this (with long numbers trimmed down for
60 clarity):
61 # RSA 2048 bits xy.example.com Sat Apr 15 13:53:22 2000
64 # for signatures only, UNSAFE FOR ENCRYPTION
65 #pubkey=0sAQOF8tZ2NZt...Y1P+buFuFn/
66 Modulus: 0xcc2a86fcf440...cf1011abb82d1
67 PublicExponent: 0x03
68 # everything after this point is secret
69 PrivateExponent: 0x881c59fdf8...ab05c8c77d23
70 Prime1: 0xf49fd1f779...46504c7bf3
71 Prime2: 0xd5a9108453...321d43cb2b
72 Exponent1: 0xa31536a4fb...536d98adda7f7
73 Exponent2: 0x8e70b5ad8d...9142168d7dcc7
74 Coefficient: 0xafb761d001...0c13e98d98
75 The first (comment) line, indicating the nature and date of the key,
79 and giving a host name, is used by ipsec_showhostkey(8) when generating
80 some forms of key output.
81 The commented-out pubkey= line contains the public key, the public
83 exponent and the modulus combined in approximately RFC 2537 format (the
84 one deviation is that the combined value is given with a 0s prefix,
85 rather than in unadorned base-64), suitable for use in the ipsec.conf
86 file.
87 The Modulus, PublicExponent and PrivateExponent lines give the basic
89 signing and verification data.
90 The Prime1 and Prime2 lines give the primes themselves (aka p and q),
92 largest first. The Exponent1 and Exponent2 lines give the private
93 exponent mod p-1 and q-1 respectively. The Coefficient line gives the
94 Chinese Remainder Theorem coefficient, which is the inverse of q, mod
95 p. These additional numbers (which must all be kept as secret as the
96 private exponent) are precomputed aids to rapid signature generation.
97 When NSS is used, these values are not available outside the NSS
98 security database (software token or hardware token) and are instead
99 filled in with the CKA_ID.
100 No attempt is made to break long lines.
102 The US patent on the RSA algorithm expired 20 Sept 2000.
104
106 ipsec rsasigkey --verbose 4096 >mykey.txt
107 generates a 4096-bit signature key and puts it in the file
108 mykey.txt, with running commentary on standard error. The file
109 contents can be inserted verbatim into a suitable entry in the
110 ipsec.secrets file (see ipsec_secrets(5)), and the public key can
111 then be extracted and edited into the ipsec.conf (see
112 ipsec_showhostkey(8)).
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115 /dev/random, /dev/urandom
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118 random(4), rngd(8), ipsec_showhostkey(8), Applied Cryptography, 2nd.
119 ed., by Bruce Schneier, Wiley 1996, RFCs 2537, 2313, GNU MP, the GNU
120 multiple precision arithmetic library, edition 2.0.2, by Torbj Granlund
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123 Originally written for the Linux FreeS/WAN project
124 <http://www.freeswan.org> by Henry Spencer. Updated for the Libreswan
125 Project by Paul Wouters.
126 The --round and --noopt options were obsoleted as these were only used
128 with the old non-library crypto code
129 The --random device is only used for seeding the crypto library, not
131 for direct random to generate keys
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134 There is an internal limit on nbits, currently 20000.
135 rsasigkey´s run time is difficult to predict, since /dev/random output
137 can be arbitrarily delayed if the system´s entropy pool is low on
138 randomness, and the time taken by the search for primes is also
139 somewhat unpredictable. Specifically, embedded systems and most virtual
140 machines are low on entropy. In such a situation, consider generating
141 the RSA key on another machine, and copying ipsec.secrets and the
142 ipsec.d/*db files to the embedded platform. Note that NSS embeds the
143 full path in the DB files, so the path on proxy machine must be
144 identical to the path on the destination machine.
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147 Paul Wouters
148 placeholder to suppress warning
149libreswan 10/04/2017 IPSEC_RSASIGKEY(8)