What do the symbols ⊞ and ⊕ mean? I'm trying to understand them to make an app.
It's on http://en.wikipedia.org/wiki/File:XXTEA.png
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1From the context it is obvious that the squared + is simply an addition.– SK-logicMar 13, 2011 at 16:54
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There's some reference code here, but the single letter variables are giving me a headache. Why does crypto code always look evil to me?– KevinJan 12, 2015 at 15:18
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2 Answers
I know for a fact that ⊕ means XOR, or eXclusive OR. With the variables A and B, Normal OR will return true if
- A=true and b=false
- A=false and B=true
- A=true and B=true
XOR on the other hand returns true only if
- A=false and B=true
- A=true and B=false
I'm not too sure about ⊞ though. In Unicode its under "SQUARED PLUS", but I don't know how that works in an algorithm
I know this is old, but I'll answer the question anyway for future readers:
⊕is the XOR function, where two identical bits produce0, and two different bits produce1.⊞is a modular addition function, where the modulus must be clearly defined in advance (such asa ⊞ b = a + b mod 2^32).<<nis the left logical bit-shift operator, shifted n-bits (not circular). Left shifting 1-bit would be equivalent to multiplying by 2.>>nin the signed right logical bit-shift operator, shifted n-bits (not circular). Right shifting 1-bit would be equivalent to dividing by 2 and taking the floor of the result.
