You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
74 lines
3.4 KiB
74 lines
3.4 KiB
MODULI(5) File Formats Manual MODULI(5) |
|
|
|
NAME |
|
moduli M-bM-^@M-^S Diffie-Hellman moduli |
|
|
|
DESCRIPTION |
|
The /etc/moduli file contains prime numbers and generators for use by |
|
sshd(8) in the Diffie-Hellman Group Exchange key exchange method. |
|
|
|
New moduli may be generated with ssh-keygen(1) using a two-step process. |
|
An initial candidate generation pass, using ssh-keygen -G, calculates |
|
numbers that are likely to be useful. A second primality testing pass, |
|
using ssh-keygen -T, provides a high degree of assurance that the numbers |
|
are prime and are safe for use in Diffie-Hellman operations by sshd(8). |
|
This moduli format is used as the output from each pass. |
|
|
|
The file consists of newline-separated records, one per modulus, |
|
containing seven space-separated fields. These fields are as follows: |
|
|
|
timestamp The time that the modulus was last processed as |
|
YYYYMMDDHHMMSS. |
|
|
|
type Decimal number specifying the internal structure of |
|
the prime modulus. Supported types are: |
|
|
|
0 Unknown, not tested. |
|
2 "Safe" prime; (p-1)/2 is also prime. |
|
4 Sophie Germain; 2p+1 is also prime. |
|
|
|
Moduli candidates initially produced by ssh-keygen(1) |
|
are Sophie Germain primes (type 4). Further primality |
|
testing with ssh-keygen(1) produces safe prime moduli |
|
(type 2) that are ready for use in sshd(8). Other |
|
types are not used by OpenSSH. |
|
|
|
tests Decimal number indicating the type of primality tests |
|
that the number has been subjected to represented as a |
|
bitmask of the following values: |
|
|
|
0x00 Not tested. |
|
0x01 Composite number M-bM-^@M-^S not prime. |
|
0x02 Sieve of Eratosthenes. |
|
0x04 Probabilistic Miller-Rabin primality tests. |
|
|
|
The ssh-keygen(1) moduli candidate generation uses the |
|
Sieve of Eratosthenes (flag 0x02). Subsequent |
|
ssh-keygen(1) primality tests are Miller-Rabin tests |
|
(flag 0x04). |
|
|
|
trials Decimal number indicating the number of primality |
|
trials that have been performed on the modulus. |
|
|
|
size Decimal number indicating the size of the prime in |
|
bits. |
|
|
|
generator The recommended generator for use with this modulus |
|
(hexadecimal). |
|
|
|
modulus The modulus itself in hexadecimal. |
|
|
|
When performing Diffie-Hellman Group Exchange, sshd(8) first estimates |
|
the size of the modulus required to produce enough Diffie-Hellman output |
|
to sufficiently key the selected symmetric cipher. sshd(8) then randomly |
|
selects a modulus from /etc/moduli that best meets the size requirement. |
|
|
|
SEE ALSO |
|
ssh-keygen(1), sshd(8) |
|
|
|
STANDARDS |
|
M. Friedl, N. Provos, and W. Simpson, Diffie-Hellman Group Exchange for |
|
the Secure Shell (SSH) Transport Layer Protocol, RFC 4419, March 2006, |
|
2006. |
|
|
|
OpenBSD 6.0 September 26, 2012 OpenBSD 6.0
|
|
|