文档介绍：Practical Issues
Of course my password is the same as my pet’s name
My macaw’s name was Q47pY!3 and I change it every 90
days
— Trevor Linton
Practical Issues
Strong, effectively unbreakable crypto is universally
available (despite US government efforts)
• Don’t attack the crypto, attack the infrastructure in which it’s
used
•" " " " implementation
•" " " " users
Many infrastructure/implementation details are treated as
black boxes by developers
• Storage protection/sanitisation
• Long-term secret storage
• Key generation
Why Security is Harder than it Looks
All software has bugs
Under normal usage conditions, a % bug-free
program will rarely cause problems
A % security-bug-free program can be exploited by
ensuring the % instance is always encountered
This converts the % failure to 100% failure
Buffer Overflows
In the last year or two these have appeared in
splitvt, syslog, mount/umount, sendmail, lpr, bind, gethostbyname(), modstat, cron, login,
sendmail again, the query CGI script, newgrp, AutoSofts RTS inventory control system, host,
talkd, getopt(), sendmail yet again, FreeBSD’s , WebSite , rlogin, term, ffbconfig,
libX11, passwd/yppasswd/nispasswd, imapd, ipop3d, SuperProbe, lpd, xterm, eject, lpd again,
host, mount, the NLS library, xlock, libXt and further X11R6 libraries, talkd, fdformat, eject,
elm, cxterm, ps, fbconfig, metamail, dtterm, df, an entire range of SGI programs, ps again,
chkey, libX11, suidperl, libXt again, lquerylv, getopt() again, dtaction, at, libDtSvc, eeprom,
lpr yet again, smbmount, xlock yet again, MH-, NIS+, ordist, xlock again, ps again, bash,
rdist, login/scheme, libX11 again, sendmail for Windows NT, wm, , tgetent(), xdat,
termcap, portmir, writesrv, rcp, opengroup, d, rlogin, MSIE, eject, df, statd, at again,
rlogin again, rsh, ping, traceroute, Cisco 7xx routers, xscreensaver, passwd, deliver, cidentd,
Xserver, the Yapp conferencing ser