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+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 6.4                   September 26, 2012                   OpenBSD 6.4