by Erica Sadun

So I'm working on this article about iPod notes and the stuff you can do with them and I decide to peek inside the latest firmware to see whether (as usual) Apple left behind some extra features.

Sure enough, I do a "strings" on the firmware and it turns out that one of the built-in tags for iPod notes is Rot13.

Rot13 for heaven's sake.

I tried it out. It works.

Why on earth would Apple want to include a Rot13 markup tag on an iPod? Can anyone think of a single good reason for this "feature"?

I'm dumbfounded.



2006-11-06 13:45:55
Better ROT-13 than ROT-26. It's probably something that someone coded up just because they could and then forgot to take it out.
2006-11-06 13:53:46
Well, Rot13 is used for simple obscuration on sites for things like television show spoilers, movie spoilers, etc. It's easy to decipher for those who want to know, but easy for people to ignore who don't want to know. I'm thinking it can be used the same way on iPods.
Erica Sadun
2006-11-06 14:41:51
NakedG, on the iPod it's one-way only. No way to obscure/deobscure it. You'd have to translate by hand to deRot13 the text--so why use <ROT13> in the first place?
Erica Sadun
2006-11-06 14:42:32
Frankenstein, I was thinking something along those lines myself (ROT-26-hee!) but I was hoping there might be some better reasoning behind the inclusion.
2006-11-06 15:50:20
It's documented in the latest iPod Notes Feature Guide (page 21) as a way to obscure the contents of a note. It could be used to make a "museum mode" presentation a little harder to steal and modify. Not a great choice, but slightly better than nothing.

2006-11-06 16:14:35
one-way rot13? how does that work?
Erica Sadun
2006-11-06 16:23:41
Thanks Logich. The new feature guide apparently just came out a few days ago and I'd missed it. I'm still baffled by the why of the Rot 13 though. Copy protection is a good thought, but there are surely a lot less clunky ways of going about it. Especially when you consider all the users who would get very confused by the Rot13 text and then go complain to the establishment about broken iPods or--worse!--try banging the little rascals to fix that funny-looking text.

2006-11-06 16:24:14
Will: There's no way *on* the iPod to reverse the rot13 text.
Zac White
2006-11-06 18:53:55
Yeah, there is no way to un-rot13 on the iPod...but the point is you rot13 it before to protect your data on some very small level and then the iPod undoes it for you. I guess you might want to do that on a text game or something so that the end can still be a surprise if someone goes poking in the text.
Tom von S.
2006-11-06 20:58:49
There is no deRot13, just rot13 it again.
Jochen Wolters
2006-11-07 01:26:10
You'd have to translate by hand to deRot13 the text--so why use in the first place?

There is no need for an additional deRot13() method, as rot13() is "self-inverse", i.e., rot13(rot13("some string")) == "some string". has a bit more information on this.

Erica Sadun
2006-11-07 01:57:42
Jochen, Yes I'm aware that Rot13(Rot13(x)) = x. My point was that this is a markup tag that does not allow any interaction on behalf of the reader so any decryption would have to be done by hand. Zac has a good point about obscuring casual inspection outside of the iPod note system, but I'm not certain under what circumstances one would ever need to obfusticate iPod note source material.
2006-11-07 04:02:59
Digital Millenium Copyright Act (DMCA)?

2006-11-07 06:33:45
Paranoid: Good thought, but I'm pretty sure that copyright issues have nothing to do with this tag.
Jochen Wolters
2006-11-08 06:46:28
Sorry, Erica, I didn't realize that this literally is just a tag. In that case, I'm just as dumbfounded as you are. :)