[Bitcoin-development] BIP 38 NFC normalisation issue

Mike Hearn mike at plan99.net
Thu Jul 17 10:59:26 UTC 2014


Glad we got to the bottom of that. That's quite a nasty compiler/language
bug I must say. Not even a warning. Still, python crashes when trying to
print the name of a null character. It wouldn't surprise me if there are
other weird issues lurking. Would definitely sleep better with a more
restricted character set.
On 17 Jul 2014 00:04, "Andreas Schildbach" <andreas at schildbach.de> wrote:

> Please excuse me. I had a more thorough look at the original problem and
> found that the only problem with the original test case was that you
> cannot specify codepoints from the SMP using \u in Java. I always tried
> \u010400 but that doesn't work.
>
> Here is a fix for bitcoinj. The test now passes.
>
> https://github.com/bitcoinj/bitcoinj/pull/143
>
> We can (and probably should) still need to filter control chars, I'll
> have a look at that now again.
>
>
> On 07/16/2014 11:06 PM, Aaron Voisine wrote:
> > If I first remove \u0000, so the non-normalized passphrase is
> > "\u03D2\u0301\U00010400\U0001F4A9", and then NFC normalize it, it
> > becomes "\u03D3\U00010400\U0001F4A9"
> >
> > UTF-8 encoded this is: 0xcf93f0909080f09f92a9 (not the same as what
> > you got, Andreas!)
> >
> > Encoding private key: 5Jajm8eQ22H3pGWLEVCXyvND8dQZhiQhoLJNKjYXk9roUFTMSZ4
> > with this passphrase, I get a BIP38 key of:
> > 6PRW5o9FMb4hAYRQPmgcvVDTyDtr6R17VMXGLmvKjKVpGkYhBJ4uYuR9wZ
> >
> > I recommend rather than simply removing control characters from the
> > password that instead the spec require that passwords containing
> > control characters are invalid. We don't want people trying to be
> > clever and putting them in thinking they are adding to the password
> > entropy.
> >
> > Also for UI compatibility across many platforms, I'm also in favor
> > disallowing any character below U+0020 (space)
> >
> > I can submit a PR once we figure out why Andreas's passphrase was
> > different than what I got.
> >
> > Aaron Voisine
> > breadwallet.com
> >
> >
> > On Wed, Jul 16, 2014 at 4:04 AM, Andreas Schildbach
> > <andreas at schildbach.de> wrote:
> >> Damn, I just realized that I implement only the decoding side of BIP38.
> >> So I cannot propose a complete test vector. Here is what I have:
> >>
> >>
> >> Passphrase: ϓ␀𐐀💩 (\u03D2\u0301\u0000\U00010400\U0001F4A9; GREEK
> >> UPSILON WITH HOOK, COMBINING ACUTE ACCENT, NULL, DESERET CAPITAL LETTER
> >> LONG I, PILE OF POO)
> >>
> >> Passphrase bytes after removing ISO control characters and NFC
> >> normalization: 0xcf933034303066346139
> >>
> >> Bitcoin Address: 16ktGzmfrurhbhi6JGqsMWf7TyqK9HNAeF
> >>
> >> Unencrypted private key (WIF):
> >> 5Jajm8eQ22H3pGWLEVCXyvND8dQZhiQhoLJNKjYXk9roUFTMSZ4
> >>
> >>
> >> Can someone calculate the encrypted key from it (using whatever
> >> implementation) and I will verify it decodes properly in bitcoinj?
> >>
> >>
> >>
> >> On 07/16/2014 12:46 PM, Andreas Schildbach wrote:
> >>> 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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> >>>>     > search up to 200,000 lines of code with a free copy of Black
> Duck
> >>>>     > Code Sight - the same software that powers the world's largest
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> >>>>     > http://p.sf.net/sfu/bds
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> >>>>
> >>>>
> >>>>
> >>>>
> ------------------------------------------------------------------------------
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> Index and
> >>>>     search up to 200,000 lines of code with a free copy of Black Duck
> >>>>     Code Sight - the same software that powers the world's largest
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> >>>>     _______________________________________________
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> >>>>
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> >>>>
> >>>>
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> >>>
> >>>
> >>>
> >>>
> ------------------------------------------------------------------------------
> >>> Want fast and easy access to all the code in your enterprise? Index and
> >>> search up to 200,000 lines of code with a free copy of Black Duck
> >>> Code Sight - the same software that powers the world's largest code
> >>> search on Ohloh, the Black Duck Open Hub! Try it now.
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> >>>
> >>
> >>
> >>
> >>
> ------------------------------------------------------------------------------
> >> Want fast and easy access to all the code in your enterprise? Index and
> >> search up to 200,000 lines of code with a free copy of Black Duck
> >> Code Sight - the same software that powers the world's largest code
> >> search on Ohloh, the Black Duck Open Hub! Try it now.
> >> http://p.sf.net/sfu/bds
> >> _______________________________________________
> >> Bitcoin-development mailing list
> >> Bitcoin-development at lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
> >
> >
> ------------------------------------------------------------------------------
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> > search up to 200,000 lines of code with a free copy of Black Duck
> > Code Sight - the same software that powers the world's largest code
> > search on Ohloh, the Black Duck Open Hub! Try it now.
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> > _______________________________________________
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> >
>
>
>
>
> ------------------------------------------------------------------------------
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> search up to 200,000 lines of code with a free copy of Black Duck
> Code Sight - the same software that powers the world's largest code
> search on Ohloh, the Black Duck Open Hub! Try it now.
> http://p.sf.net/sfu/bds
> _______________________________________________
> Bitcoin-development mailing list
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