the meaning of linearity

[Florian Weimer]

* Travis H.:

> This reminds me, when people talk about linearity with regard to a
> function, for example CRCs, exactly what sense of the word do they
> mean?  I can understand f(x) = ax + b being linear,

I wouldn't call that "linear" if b /= 0, "affine" is probably better.
But I'm not familiar with the cryptographic term, maybe it's
different.

> but how exactly does XOR get involved, and are there +-linear
> functions and xor-linear functions?  Are they disjoint?  etc.

It refers to arithmetic over GF(2), the field with two elements.  In
this field, XOR is addition, and AND is multiplication.

---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at metzdowd.com