I currently use: * "positive validation" for validations that specifically only allow specific characters; and * "negative validation" for validations that allow everything but a small range of "illegal" characters (wrong! evil! if you don't already know). I am not the only one using this meaning. Check out this CERT Perl example for another person's use of the same term, with the same meaning: http://www.cert.org/tech_tips/malicious_code_mitigation.html#8 I believe we shouldn't confuse people with a oxymoron (ie "inclusion" normally means accepting as much as you can, when that's clearly not the case here). The "principle of least inclusion" is possibly a better choice, if you want to make a "principle". Andrew -----Original Message----- From: aleph1at_private [mailto:aleph1at_private] Sent: Wednesday, 27 June 2001 04:23 To: secprogat_private Subject: Principle of Inclusion? We have all heard the old security principle of not filtering out known bad input but filtering in known good input, but I've never heard it "named" like we name the "principle of least privilege". Do you know of any such name? I am thinking of simply christening the principle of inclusion. I am defining it as: The principle of inclusion tells us that when performing input validation for security purposes we should not define what is considered invalid input and refuse any input that matches this definition, since our definition of what is invalid may not be complete, and that instead we should define what is considered valid input and refuse any input that does not match this definition. -- Elias Levy SecurityFocus.com http://www.securityfocus.com/ Si vis pacem, para bellum
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