[Bitcoin-development] BIP 38 NFC normalisation issue

Mike Hearn mike at plan99.net
Wed Jul 16 09:29:16 UTC 2014


Yes sorry, you're right, the issue starts with the null code point. Python
seems to have problems starting there too. It might work if we took that
out.


On Wed, Jul 16, 2014 at 11:17 AM, Andreas Schildbach <andreas at schildbach.de>
wrote:

> Guys, you are always talking about the Unicode astral plane, but in fact
> its a plain old (ASCII) control character where this problem starts and
> likely ends: \u0000.
>
> Let's ban/filter ISO control characters and be done with it. Most
> control characters will never be enterable by any keyboard into a
> password field. Of course I assume that Character.isISOControl() works
> consistently across platforms.
>
>
> http://docs.oracle.com/javase/7/docs/api/java/lang/Character.html#isISOControl%28char%29
>
>
> On 07/16/2014 12:23 AM, Aaron Voisine wrote:
> > If the user creates a password on an iOS device with an astral
> > character and then can't enter that password on a JVM wallet, that
> > sucks. If JVMs really can't support unicode NFC then that's a strong
> > case to limit the spec to the subset of unicode that all popular
> > platforms can support, but it sounds like it might just be a JVM
> > string library bug that could hopefully be reported and fixed. I get
> > the same result as in the test case using apple's
> > CFStringNormalize(passphrase, kCFStringNormalizationFormC);
> >
> > Aaron Voisine
> > breadwallet.com
> >
> >
> > On Tue, Jul 15, 2014 at 11:20 AM, Mike Hearn <mike at plan99.net> wrote:
> >> Yes, we know, Andreas' code is indeed doing normalisation.
> >>
> >> However it appears the output bytes end up being different. What I get
> back
> >> is:
> >>
> >> cf930001303430300166346139
> >>
> >> vs
> >>
> >> cf9300f0909080f09f92a9
> >>
> >> from the spec.
> >>
> >> I'm not sure why. It appears this is due to the character from the
> astral
> >> planes. Java is old and uses 16 bit characters internally - it wouldn't
> >> surprise me if there's some weirdness that means it doesn't/won't
> support
> >> this kind of thing.
> >>
> >> I recommend instead that any implementation that wishes to be compatible
> >> with JVM based wallets (I suspect Android is the same) just refuse any
> >> passphrase that includes characters outside the BMP. At least unless
> someone
> >> can find a fix. I somehow doubt this will really hurt anyone.
> >>
> >>
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> >
> >
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>
>
>
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