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MODULI(5)		    BSD	File Formats Manual		     MODULI(5)

     moduli -- system moduli file

     The moduli	file contains the system-wide Diffie-Hellman prime moduli for
     the photurisd(8) and sshd(8) programs.

     Each line in this file contains the following fields: Time, Type, Tests,
     Tries, Size, Generator, and Modulus.  The fields are separated by white
     space (tab	or blank).

     Time (yyyymmddhhmmss)
	     Specifies the system time that the	line was appended to the file.
	     The value 00000000000000 means unknown (historic).

     Type (decimal)
	     Specifies the internal structure of the prime modulus.

	     0	     unknown; often learned from peer during protocol opera-
		     tion, and saved for later analysis.
	     1	     unstructured; a common large number.
	     2	     safe (p = 2q + 1);	meets basic structural requirements.
	     3	     Schnorr.
	     4	     Sophie-Germaine (q	= (p-1)/2); usually generated in the
		     process of	testing	safe or	strong primes.
	     5	     strong; useful for	RSA public key generation.

     Tests (decimal) (bit field)
	     Specifies the methods used	in checking for	primality.  Usually,
	     more than one test	is used.

	     0	     not tested; often learned from peer during	protocol oper-
		     ation, and	saved for later	analysis.
	     1	     composite;	failed one or more tests.  In this case, the
		     highest bit specifies the test that failed.
	     2	     sieve; checked for	division by a range of smaller primes.
	     4	     Miller-Rabin.
	     8	     Jacobi.
	     16	     Elliptic Curve.

     Tries (decimal)
	     Depends on	the value of the highest valid Test bit, where the
	     method specified is:

	     0	     not tested	(always	zero).
	     1	     composite (irrelevant).
	     2	     sieve; number of primes sieved.  Commonly on the order of
	     4	     Miller-Rabin; number of M-R iterations.  Commonly on the
		     order of 32 to 64.
	     8	     Jacobi; unknown (always zero).
	     16	     Elliptic Curve; unused (always zero).

     Size (decimal)
	     Specifies the number of significant bits.

     Generator (hex string)
	     Specifies the best	generator for a	Diffie-Hellman exchange.  0 =
	     unknown or	variable, 2, 3,	5, etc.

     Modulus (hex string)
	     The prime modulus.

     The file is searched for moduli that meet the appropriate Time, Size and
     Generator criteria.  When more than one meet the criteria,	the selection
     should be weighted	toward newer moduli, without completely	disqualifying
     older moduli.


     photurisd(8), sshd(8)

BSD				 July 28, 1997				   BSD


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