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NTP.KEYS(5)		    BSD	File Formats Manual		   NTP.KEYS(5)

     ntp.keys -- NTP daemon key	file format


     Following is a description	of the format of NTP key files.	 For a de-
     scription of the use of these files, see the "Authentication Support"
     section of	the ntp.conf(5)	page.

     In	the case of DES, the keys are 56 bits long with, depending on type, a
     parity check on each byte.	 In the	case of	MD5, the keys are 64 bits (8
     bytes).  ntpd(8) reads its	keys from a file specified using the -k	com-
     mand line option or the keys statement in the configuration file.	While
     key number	0 is fixed by the NTP standard (as 56 zero bits) and may not
     be	changed, one or	more of	the keys numbered 1 through 15 may be arbi-
     trarily set in the	keys file.

     The key file uses the same	comment	conventions as the configuration file.
     Key entries use a fixed format of the form

	   keyno type key

     where keyno is a positive integer,	type is	a single character which de-
     fines the key format, and key is the key itself.

     The key may be given in one of four different formats, controlled by the
     type character.  The four key types, and corresponding formats, are
     listed following.

     S	The key	is a 64-bit hexadecimal	number in the format specified in the
	DES specification; that	is, the	high order seven bits of each octet
	are used to form the 56-bit key	while the low order bit	of each	octet
	is given a value such that odd parity is maintained for	the octet.
	Leading	zeroes must be specified (i.e.,	the key	must be	exactly	16 hex
	digits long) and odd parity must be maintained.	 Hence a zero key, in
	standard format, would be given	as `0101010101010101'.

     N	The key	is a 64-bit hexadecimal	number in the format specified in the
	NTP standard.  This is the same	as the DES format, except the bits in
	each octet have	been rotated one bit right so that the parity bit is
	now the	high order bit of the octet.  Leading zeroes must be specified
	and odd	parity must be maintained.  A zero key in NTP format would be
	specified as `8080808080808080'.

     A	The key	is a 1-to-8 character ASCII string.  A key is formed from this
	by using the low order 7 bits of each ASCII character in the string,
	with zeroes added on the right when necessary to form a	full width
	56-bit key, in the same	way that encryption keys are formed from UNIX

     M	The key	is a 1-to-8 character ASCII string, using the MD5 authentica-
	tion scheme.  Note that	both the keys and the authentication schemes
	(DES or	MD5) must be identical between a set of	peers sharing the same
	key number.

     Note that the keys	used by	the ntpq(8) and	ntpdc(8) programs are checked
     against passwords requested by the	programs and entered by	hand, so it is
     generally appropriate to specify these keys in ASCII format.

     /etc/ntp.keys   the default name of the configuration file

     ntp.conf(5), ntpd(8), ntpdate(8), ntpdc(8)

     ntpd(8) has gotten	rather fat.  While not huge, it	has gotten larger than
     might be desirable	for an elevated-priority daemon	running	on a worksta-
     tion, particularly	since many of the fancy	features which consume the
     space were	designed more with a busy primary server, rather than a	high
     stratum workstation, in mind.

BSD			       January 13, 2000				   BSD


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