summaryrefslogtreecommitdiff
path: root/moduli.0
diff options
context:
space:
mode:
authorColin Watson <cjwatson@debian.org>2010-08-23 22:50:14 +0100
committerColin Watson <cjwatson@debian.org>2010-08-23 22:50:14 +0100
commit43094ebf14c9b16f1ea398bc5b65a7335e947288 (patch)
tree10f5da5fe4f61992d238da7a71692157a609c819 /moduli.0
parent4b8ebe7e3647d3078fd4d025f4325b8cc1ac20d6 (diff)
parentff0095389ba9a9e4599e6051c8d5bae6777c4d64 (diff)
Import 5.6p1 tarball
Diffstat (limited to 'moduli.0')
-rw-r--r--moduli.073
1 files changed, 73 insertions, 0 deletions
diff --git a/moduli.0 b/moduli.0
new file mode 100644
index 000000000..6d707ff82
--- /dev/null
+++ b/moduli.0
@@ -0,0 +1,73 @@
1MODULI(5) OpenBSD Programmer's Manual MODULI(5)
2
3NAME
4 moduli - Diffie Hellman moduli
5
6DESCRIPTION
7 The /etc/moduli file contains prime numbers and generators for use by
8 sshd(8) in the Diffie-Hellman Group Exchange key exchange method.
9
10 New moduli may be generated with ssh-keygen(1) using a two-step process.
11 An initial candidate generation pass, using ssh-keygen -G, calculates
12 numbers that are likely to be useful. A second primality testing pass,
13 using ssh-keygen -T provides a high degree of assurance that the numbers
14 are prime and are safe for use in Diffie Hellman operations by sshd(8).
15 This moduli format is used as the output from each pass.
16
17 The file consists of newline-separated records, one per modulus,
18 containing seven space separated fields. These fields are as follows:
19
20
21 timestamp The time that the modulus was last processed as
22 YYYYMMDDHHMMSS.
23
24 type Decimal number specifying the internal structure of
25 the prime modulus. Supported types are:
26
27 0 Unknown, not tested
28 2 "Safe" prime; (p-1)/2 is also prime.
29 4 Sophie Germain; (p+1)*2 is also prime.
30
31 Moduli candidates initially produced by ssh-keygen(1)
32 are Sophie Germain primes (type 4). Futher primality
33 testing with ssh-keygen(1) produces safe prime moduli
34 (type 2) that are ready for use in sshd(8). Other
35 types are not used by OpenSSH.
36
37 tests Decimal number indicating the type of primality tests
38 that the number has been subjected to represented as a
39 bitmask of the following values:
40
41 0x00 Not tested
42 0x01 Composite number - not prime.
43 0x02 Sieve of Eratosthenes
44 0x04 Probabalistic Miller-Rabin primality tests.
45
46 The ssh-keygen(1) moduli candidate generation uses the
47 Sieve of Eratosthenes (flag 0x02). Subsequent
48 ssh-keygen(1) primality tests are Miller-Rabin tests
49 (flag 0x04).
50
51 trials Decimal number indicating of primaility trials that
52 have been performed on the modulus.
53
54 size Decimal number indicating the size of the prime in
55 bits.
56
57 generator The recommended generator for use with this modulus
58 (hexadecimal).
59
60 modulus The modulus itself in hexadecimal.
61
62 When performing Diffie Hellman Group Exchange, sshd(8) first estimates
63 the size of the modulus required to produce enough Diffie Hellman output
64 to sufficiently key the selected symmetric cipher. sshd(8) then randomly
65 selects a modulus from /etc/moduli that best meets the size requirement.
66
67SEE ALSO
68 ssh-keygen(1), sshd(8),
69
70 Diffie-Hellman Group Exchange for the Secure Shell (SSH) Transport Layer
71 Protocol, RFC 4419, 2006.
72
73OpenBSD 4.8 June 26, 2008 OpenBSD 4.8