[ntp:questions] ntp-keygen -M generates keys of 20 characters, yet docs for ntp-keygen state up 16 characters

jnixon at brocade.com jnixon at brocade.com
Mon Sep 26 23:58:26 UTC 2011

I have a very dumb question, regarding what information is correct,
and what is not.
The documention states that MD5keys will be lss then or equal to 16
characters in length, and consist of a printable ASCII characters and
be terminated by whitespace or #. Yet the output of 'ntp-keygen -M',
and the examples shown in the documentation are all 20 characters in
length. Can anyone explain the difference, and what is the correct
length for the md5 keys?
Jason Nixon, Test Engineer, Brocade Communications.

>From http://www.eecis.udel.edu/~mills/ntp/html/keygen.html
4th paragraph up from the bottom.
An MD5 key consists of a printable ASCII string less than or equal to
16 characters and terminated by whitespace or a # character. An
OpenSSL key consists of a hex-encoded ASCII string of 40 characters,
which is truncated as necessary.
Yet the Figure 1.shows the MD5 keys 1 to 10, with a length of 20

>From http://www.eecis.udel.edu/~mills/ntp/html/authentic.html
Bottom section.
Each line consists of three fields, the key identifier as a decimal
number from 1 to 65,534 inclusive, a key type chosen from the keywords
of the digest option of the crypto command, and a 20-character
printable ASCII string or a 40-character hex string as the key itself.
(Figure 1. again shows the Md5 keys with a length of 20 characters)
Figure 1 shows a typical keys file used by the reference
implementation. In the case of MD5, the key consists of 16 characters
randomized over the ASCII printing codes The string can be edited
later for a password, for instance as 2late4Me for key ID 10. For
message digest algorithms other than MD5, the key is a 20-octet (40
hex digits) random hex string.

File Generated by ntp-keygen -M on my local linux box.
user at ubuntu-vm:~$ cat ntpkey_md5_ubuntu-vm
# ntpkey_MD5key_ubuntu-vm.3526065526
# Mon Sep 26 15:38:46 2011

 1 MD5 Z7b^xp"P"zfV{2hzphB-  # MD5 key
 2 MD5 07i:z$t2'u>vGXpA|U^'  # MD5 key
 3 MD5 4|BoCdm;S-A1]a>xrcMJ  # MD5 key
 4 MD5 <202+D0-6lHe'BR&jJ}z  # MD5 key
 5 MD5 )"^V3\x$5f?%QB|{uNr&  # MD5 key
 6 MD5 p`~x<G%fBPMGQimG5%$M  # MD5 key
 7 MD5 Od'bc4Y6Cq+ls`k>5U{=  # MD5 key
 8 MD5 !KYuwttcZD"16BUh>^st  # MD5 key
 9 MD5 U)<bIzJ6Dpe$Af(AQf2*  # MD5 key
10 MD5 {tu$EhsRU+CeBcC;jq<_  # MD5 key
11 SHA1 e1db4c6739a9f6c955c6a7bdece5ed7520ae9692  # SHA1 key
12 SHA1 801b3412a573fb87080e5cdde2131a57b9d0670b  # SHA1 key
13 SHA1 84f8417f2dcc9a5844fc0e4ab0065de2eac39f48  # SHA1 key
14 SHA1 c2e6d09265fba51f8f4d2fb7c726e3751d429d59  # SHA1 key
15 SHA1 98e929375acd6e0fccda82cf036e10e8a5abfc5f  # SHA1 key
16 SHA1 b7fd0547b80a40272a7a75849cb6c9da2a194462  # SHA1 key
17 SHA1 c15c91fd9437d30157ff4af820408e3a1661f8a5  # SHA1 key
18 SHA1 b5e6899011d7662cc2f47aaff96935832fef6822  # SHA1 key
19 SHA1 2b44f1934c089f3ae0fcf36ebced0f8594ed1502  # SHA1 key
20 SHA1 0fc96ae11034e36c7370f94d40b3249d0862e914  # SHA1 key
user at ubuntu-vm:~$

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