1IPSEC_RSASIGKEY(8)            Executable programs           IPSEC_RSASIGKEY(8)
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NAME

6       ipsec_rsasigkey - generate RSA signature key
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SYNOPSIS

9       ipsec rsasigkey [--verbose] [--seeddev device] [--seed numbits]
10             [--nssdir nssdir] [--password nsspassword] [--hostname hostname]
11             [nbits]
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DESCRIPTION

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.
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19       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.
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24       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.
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28       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)
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38       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.
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42       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.
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45       The --nssdir option specifies the directory to use for the nss
46       database. This is the directory where the NSS certificate, key and
47       security modules databases reside. The default value is /etc/ipsec.d.
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49       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 /etc/ipsec.d/nsspassword, the password comes from that
54       file; otherwise argument is the password.
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56       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
59       The output format looks like this (with long numbers trimmed down for
60       clarity):
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62
63                # RSA 3744 bits   road.toad.com   Mon Apr 17 22:20:35 2017
64                # for signatures only, UNSAFE FOR ENCRYPTION
65                #ckaid=a953473e6014dd4e08eb051e4679dc39be160fea
66                #pubkey=0sBAEAA...sKbTzwE=
67                Modulus: 0xb84ae7d...b0a6d3cf01
68                PublicExponent: 0x010001
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72       The first (comment) line, indicating the nature and date of the key,
73       and giving a host name, is used by ipsec_showhostkey(8) when generating
74       some forms of key output.
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76       The commented-out pubkey= line contains the public key, the public
77       exponent and the modulus combined in approximately RFC 2537 format (the
78       one deviation is that the combined value is given with a 0s prefix,
79       rather than in unadorned base-64), suitable for use in the ipsec.conf
80       file.
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82       The Modulus, PublicExponent and PrivateExponent lines give the basic
83       signing and verification data.
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85       The Prime1 and Prime2 lines give the primes themselves (aka p and q),
86       largest first. The Exponent1 and Exponent2 lines give the private
87       exponent mod p-1 and q-1 respectively. The Coefficient line gives the
88       Chinese Remainder Theorem coefficient, which is the inverse of q, mod
89       p. These additional numbers (which must all be kept as secret as the
90       private exponent) are precomputed aids to rapid signature generation.
91       When NSS is used, these values are not available outside the NSS
92       security database (software token or hardware token) and are instead
93       filled in with the CKA_ID.
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95       No attempt is made to break long lines.
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97       The US patent on the RSA algorithm expired 20 Sept 2000.
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EXAMPLES

100       ipsec rsasigkey --verbose 4096 >mykey.txt
101           generates a 4096-bit signature key and puts it in the file
102           mykey.txt, with running commentary on standard error. The file
103           contents can be inserted verbatim into a suitable entry in the
104           ipsec.secrets file (see ipsec_secrets(5)), and the public key can
105           then be extracted and edited into the ipsec.conf (see
106           ipsec_showhostkey(8)).
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FILES

109       /dev/random, /dev/urandom
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SEE ALSO

112       random(4), rngd(8), ipsec_showhostkey(8), Applied Cryptography, 2nd.
113       ed., by Bruce Schneier, Wiley 1996, RFCs 2537, 2313, GNU MP, the GNU
114       multiple precision arithmetic library, edition 2.0.2, by Torbj Granlund
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HISTORY

117       Originally written for the Linux FreeS/WAN project
118       <https://www.freeswan.org> by Henry Spencer. Updated for the Libreswan
119       Project by Paul Wouters.
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121       The --round and --noopt options were obsoleted as these were only used
122       with the old non-library crypto code
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124       The --random device is only used for seeding the crypto library, not
125       for direct random to generate keys
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BUGS

128       There is an internal limit on nbits, currently 20000.
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130       rsasigkey's run time is difficult to predict, since /dev/random output
131       can be arbitrarily delayed if the system's entropy pool is low on
132       randomness, and the time taken by the search for primes is also
133       somewhat unpredictable. Specifically, embedded systems and most virtual
134       machines are low on entropy. In such a situation, consider generating
135       the RSA key on another machine, and copying ipsec.secrets and the
136       /etc/ipsec.d directory tree to the embedded platform. Note that NSS
137       embeds the full path in the DB files, so the path on proxy machine must
138       be identical to the path on the destination machine.
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AUTHOR

141       Paul Wouters
142           placeholder to suppress warning
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146libreswan                         07/25/2019                IPSEC_RSASIGKEY(8)
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