[Bitcoin-development] BIP 38 NFC normalisation issue

[Andreas Schildbach]

I will change the bitcoinj implementation and propose a new test vector.



On 07/16/2014 11:29 AM, Mike Hearn wrote:
> 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 <mailto: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 <http://breadwallet.com>
>     >
>     >
>     > On Tue, Jul 15, 2014 at 11:20 AM, Mike Hearn <mike at plan99.net
>     <mailto: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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