1IPSEC_RSASIGKEY(8) [FIXME: manual] IPSEC_RSASIGKEY(8)
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6 ipsec_rsasigkey - generate RSA signature key
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9 ipsec rsasigkey [--verbose] [--random filename] [--rounds nr]
10 [--configdir nssdbdir] [--password nsspassword]
11 [--hostname hostname] [--noopt] nbits
12 ipsec rsasigkey [--verbose] [--configdir nssdbdir]
14 [--password nsspassword] [--hostname hostname] [--noopt]
15 [--oldkey filename]
16
18 Rsasigkey generates an RSA public/private key pair, suitable for
19 digital signatures, of (exactly) nbits bits (that is, two primes each
20 of exactly nbits/2 bits, and related numbers) and emits it on standard
21 output as ASCII (mostly hex) data. nbits must be a multiple of 16.
22 The public exponent is forced to the value 3, which has important speed
24 advantages for signature checking. Beware that the resulting keys have
25 known weaknesses as encryption keys and should not be used for that
26 purpose.
27 The --verbose option makesrsasigkey give a running commentary on
29 standard error. By default, it works in silence until it is ready to
30 generate output.
31 The --random option specifies a source for random bits. The default is
33 /dev/random (see random(4)). Normally, rsasigkey reads exactly nbits
34 random bits from the source; in extremely-rare circumstances it may
35 need more. Under Linux with hardware random support, the special device
36 /dev/hw_random is created. However, the driver does not guarantee FIPS
37 compliant random, and some hardware is so broken that it return
38 extremely non-random data. Therefor /dev/hw_random should never be used
39 with the --random option. Instead, one should run the rngd(8) daemon to
40 funnel randomness from /dev/hw_random into /dev/random.
41 The --rounds option specifies the number of rounds to be done by the
43 pz_probab_prime_p probabilistic primality checker. The default, 30, is
44 fairly rigorous and should not normally have to be overridden.
45 The --Configdir option specifies the nss configuration directory to
47 use. This is the directory where the NSS certificate, key and security
48 modules databases reside.
49 The --password option specifies the nss cryptographic module
51 authentication password if the NSS module has been configured to
52 require it. A password is required by hardware tokens and also by the
53 internal softotken module when configured to run in FIPS mode.
54 The --hostname option specifies what host name to use in the first line
56 of the output (see below); the default is what gethostname(2) returns.
57 The --hostname option suppresses an optimization of the private key (to
59 be precise, setting of the decryption exponent to lcm(p-1,q-1) rather
60 than (p-1)*(q-1)) which speeds up operations on it slightly but can
61 cause it to flunk a validity check in old RSA implementations (notably,
62 obsolete versions of ipsec_pluto(8)
63 --oldkey option specifies that rather than generate a new key,
65 rsasigkey should read an old key from the file (the name ´-´ means
66 ´standard input´) and use that to generate its output. Input lines
67 which do not look like rsasigkey output are silently ignored. This
68 permits updating old keys to the current format.
69 The output format looks like this (with long numbers trimmed down for
71 clarity):
72 # RSA 2048 bits xy.example.com Sat Apr 15 13:53:22 2000
75 # for signatures only, UNSAFE FOR ENCRYPTION
76 #pubkey=0sAQOF8tZ2NZt...Y1P+buFuFn/
77 Modulus: 0xcc2a86fcf440...cf1011abb82d1
78 PublicExponent: 0x03
79 # everything after this point is secret
80 PrivateExponent: 0x881c59fdf8...ab05c8c77d23
81 Prime1: 0xf49fd1f779...46504c7bf3
82 Prime2: 0xd5a9108453...321d43cb2b
83 Exponent1: 0xa31536a4fb...536d98adda7f7
84 Exponent2: 0x8e70b5ad8d...9142168d7dcc7
85 Coefficient: 0xafb761d001...0c13e98d98
86 The first (comment) line, indicating the nature and date of the key,
90 and giving a host name, is used by ipsec_showhostkey(8) when generating
91 some forms of key output.
92 The commented-out pubkey= line contains the public key, the public
94 exponent and the modulus combined in approximately RFC 2537 format (the
95 one deviation is that the combined value is given with a 0s prefix,
96 rather than in unadorned base-64), suitable for use in the ipsec.conf
97 file.
98 The Modulus, PublicExponent and PrivateExponent lines give the basic
100 signing and verification data.
101 The Prime1 and Prime2 lines give the primes themselves (aka p and q),
103 largest first. The Exponent1 and Exponent2 lines give the private
104 exponent mod p-1 and q-1 respectively. The Coefficient line gives the
105 Chinese Remainder Theorem coefficient, which is the inverse of q, mod
106 p. These additional numbers (which must all be kept as secret as the
107 private exponent) are precomputed aids to rapid signature generation.
108 No attempt is made to break long lines.
110 The US patent on the RSA algorithm expired 20 Sept 2000.
112
114 ipsec rsasigkey --verbose 2192 >mykey.txt
115 generates a 2192-bit signature key and puts it in the file
116 mykey.txt, with running commentary on standard error. The file
117 contents can be inserted verbatim into a suitable entry in the
118 ipsec.secrets file (see ipsec_secrets(5)), and the public key can
119 then be extracted and edited into the ipsec.conf (see
120 ipsec_showhostkey(8)).
121 ipsec rsasigkey --verbose --oldkey oldie >latest.txt
123 takes the old signature key from file oldie and puts a version in
124 the current format into the file latest, with running commentary on
125 standard error.
126
128 /dev/random, /dev/urandom
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131 random(4), rngd(8), ipsec_showhostkey(8), Applied Cryptography, 2nd.
132 ed., by Bruce Schneier, Wiley 1996, RFCs 2537, 2313, GNU MP, the GNU
133 multiple precision arithmetic library, edition 2.0.2, by Torbj Granlund
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136 Written for the Linux FreeS/WAN project <http://www.freeswan.org> by
137 Henry Spencer.
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140 There is an internal limit on nbits, currently 20000.
141 rsasigkey´s run time is difficult to predict, since /dev/random output
143 can be arbitrarily delayed if the system´s entropy pool is low on
144 randomness, and the time taken by the search for primes is also
145 somewhat unpredictable. A reasonably typical time for a 1024-bit key on
146 a quiet 100MHz Pentium MMX with plenty of randomness available is 20
147 seconds, almost all of it in the prime searches. Generating a 2192-bit
148 key on the same system usually takes several minutes. A 4096-bit key
149 took an hour and a half of CPU time.
150 The --oldkey option does not check its input format as rigorously as it
152 might. Corrupted rsasigkey output may confuse it.
153[FIXME: source] 10/06/2010 IPSEC_RSASIGKEY(8)