From: Phillip M Hallam-Baker <pbaker@verisign.com>

Date: Wed, 25 Aug 1999 13:04:18 -0400

To: "Donald E. Eastlake 3rd" <dee3@torque.pothole.com>, "IETF/W3C XML-DSig WG" <w3c-ietf-xmldsig@w3.org>

Message-ID: <000801beef1b$de1ab400$6e07a8c0@pbaker-pc.verisign.com>

Date: Wed, 25 Aug 1999 13:04:18 -0400

To: "Donald E. Eastlake 3rd" <dee3@torque.pothole.com>, "IETF/W3C XML-DSig WG" <w3c-ietf-xmldsig@w3.org>

Message-ID: <000801beef1b$de1ab400$6e07a8c0@pbaker-pc.verisign.com>

> >The definition of canonicalization is a function f(x) such that > >f(x) = f(f(x)). > > No. That's the fix point property, which is a desireable property of > canonicalization but by no means its definition. Actually it is a required property for it to be a canonical form. The point of canonicalization is to be able to test for equivalence between different syntactical representations of the same data. > My definition of > canonicalization is a function f(x) which is useful for application A > if f(x1) = f(x2) implies that application A considers x1 and x2 > semantically identical. And f(x1) <> f(x2) implies they are distinct. Therefore a c14n function must have the fixed point property. Lema Exists f(x) <> f(f(x)) for some x => f(x) <> f(x2) where x2 = f(f(x)) but x, x2 are semantically equivalent, therefore f(x) = f(x2), thus disproving the lema. Therefore all canonicalization functions are fixed point functions QED.Received on Wednesday, 25 August 1999 13:03:56 UTC

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