# Security + Privacy = ...

April 3, 2012

One of the goals of the Revocable Privacy project is to show that security and privacy are not a zero sum game. The question is: if the sum is not zero, what is it...

We have

`_SECURITY __PRIVACY ---------+ NOTEQZERO`

Each symbol represents a digit. We have more than 10 symbols, but require that at least all digits occur in this sum.

To make the sum correct for the most significant digits of the result (N and O), a little reasoning shows that S=9, N=1 and O=0. We now have

`_1 _9ECURITY __PRIVACY ---------+ 10TEQZER0`

with a carry that must be the result of E+P (more about that later)

Now lets turn to the least significant digits. We see Y+Y=0 (or 10). So we set Y=5. This gives

`_1     1 _9ECURIT5 __PRIVAC5 ---------+ 10TEQZER0`

Now we turn to C and R. They occur in two columns of the sum: we have C+R=E and we have R-C=T+1. As a consequence, if C and R are both even or both odd, then E is even and T is odd. If the parity of C and R is unequal, then E is odd and T is even.

Moreover, E+P=10+T (because of the required carry). Several combinations for E and P satisfying the constraint that E+P>10 have to be tried until we find a combination that 'works': E=3, P=7 and hence T=0.

`_1     1 _93CURI05 __7RIVAC5 ---------+ 1003QZ3R0`

This also fixes C=1 and R=2 (by C+R=3 and we have R-C=1)

`_1     1 _931U2I05 __72IVA15 ---------+ 1003QZ320`

Now this leaves us to assign the values 4, 6 and 8. We have the requirement 2+V=Z so setting V=6 and Z=8 assigns two of these values.

`_1     1 _931U2I05 __72I6A15 ---------+ 1003Q8320`

This leaves I+A=3 and U+I=Q, and the constraint that the value 4 is not used yet. Let's set Q=4. Then I=1, A=2 and U=3 satisfy the equations and yields the end result.

`_1     1 _93132105 __7216215 ---------+ 100348320`

Now we ask ourselves: what is this number? A google search gives us the answer: a beautiful woman, as symbol of the beautiful road ahead when security and privacy escape from the trenches and go ahead hand-in-hand together...

And don't worry: I've been accused of being uncurably optimistic before ;-)