Can you solve this keygen problem?

[Stingered]

Originally Posted by dila

There are only 63 valid keys (shown below). I won't post my generator, since you pretty much solved it already.

Actually, 0x0000000000000000 (the all-zero key) is also accepted by the loop, but the check routine explicitly disallows this as a solution at the end.

I would not say that 64 keys out of a 2^64 input space is "a lot". The challenge was deliberately created to have only a few solutions.

aaaaaaaaaaaaaaaa
cccccccccccccccc
6666666666666666
f0f0f0f0f0f0f0f0
5a5a5a5a5a5a5a5a
3c3c3c3c3c3c3c3c
9696969696969696
ff00ff00ff00ff00
55aa55aa55aa55aa
33cc33cc33cc33cc
9966996699669966
ff00ff00ff00ff0
a55aa55aa55aa55a
c33cc33cc33cc33c
6996699669966996
ffff0000ffff0000
5555aaaa5555aaaa
3333cccc3333cccc
9999666699996666
f0ff0f00f0ff0f0
a5a55a5aa5a55a5a
c3c33c3cc3c33c3c
6969969669699696
ffff0000ffff00
aa5555aaaa5555aa
cc3333cccc3333cc
6699996666999966
f00f0ff0f00f0ff0
5aa5a55a5aa5a55a
3cc3c33c3cc3c33c
9669699696696996
ffffffff00000000
55555555aaaaaaaa
33333333cccccccc
9999999966666666
f0f0f0ff0f0f0f0
a5a5a5a55a5a5a5a
c3c3c3c33c3c3c3c
6969696996969696
ff00ffff00ff00
aa55aa5555aa55aa
cc33cc3333cc33cc
6699669999669966
f00ff00f0ff00ff0
5aa55aa5a55aa55a
3cc33cc3c33cc33c
9669966969966996
ffffffff0000
aaaa55555555aaaa
cccc33333333cccc
6666999999996666
f0f00f0f0f0ff0f0
5a5aa5a5a5a55a5a
3c3cc3c3c3c33c3c
9696696969699696
ff0000ff00ffff00
55aaaa55aa5555aa
33cccc33cc3333cc
9966669966999966
ff0f00ff00f0ff0
a55a5aa55aa5a55a
c33c3cc33cc3c33c
6996966996696996

I'd actually like to see the code, if you are so inclined. I'm fairly weak in this area and could use any example to walk through.