Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id A6146EDF for ; Mon, 8 Jan 2018 22:26:24 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-wr0-f195.google.com (mail-wr0-f195.google.com [209.85.128.195]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 3495544D for ; Mon, 8 Jan 2018 22:26:23 +0000 (UTC) Received: by mail-wr0-f195.google.com with SMTP id w107so12308019wrb.9 for ; Mon, 08 Jan 2018 14:26:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=hTcezkblQNRBlImOjofPNFKKWHjytoLzN7zMuoUIPSU=; b=PppK8X583hKtcKbfDvBbtGZ67chlhtXpOOwEVufsHgrbqLSdH7q3AIDcK+M5mKawQw ic6Av4c63M5AAIDcu6TyMML5UmiWo3BVsxcKTO56xzdC/F/62CUMX73NpXfLr+DnUm+m asXVftmmZHATpspjpGVMjpIXfKC5PSwlS0wSYnvEDhnpqiPPMBCSIVkNNR9N/HbBZCv6 xliqWUZcCvhQJz1OOxf0EZpqwypgMDHo26j71NiDbJZUjTYXX9g64X4Wt1tkCrpwMSKV WQRanYBNRgLtgMWgkPoCjezYMtCSRrap5ar+Z4VJKad6CFFyHsjbmp9d6wTGYRpzy+bm qUAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=hTcezkblQNRBlImOjofPNFKKWHjytoLzN7zMuoUIPSU=; b=IaJb2W8lyuCkd8BZ7EkUC/oDT0tvwVwt5rX/JCRe1l6Xz++ZAL+mHpiX2mbklUNGdw 5CEU0rX5xYWE9GCpZZa3cj9FQa3SH3iE8m1WOboC6D2RY7IQPiP8ViooeClaTa8/5o94 5e83jztY2Vyr1GeLSHMJm+Uwp7AcolCBh3HRmMpwDmAQw0U/chEGQ+9rtrZqMwzbg2xX qw6QzC362tQsR4VlvlPxZQTIATFazAbofdCfuAuIdDrMpf9zTumczQqt0hSvf+yG7PGu 662cjFBSW31wNs/eUyQP85lHfC61yNiFbj1T7ZV3Ycc3Ju14tZcaPHcMjiy0mXrM+tlC yd2w== X-Gm-Message-State: AKGB3mI7lYUZtuuzUKzOY7i+4qowNtkpZ4jTWxCtrWUU+uW4DWkQtAei Yo1STB0pYbqfhuHW8IbPJRfmgZam2xOvnyiUDA+ymchZ X-Google-Smtp-Source: ACJfBosEtw3wwm0Rzghx4ecbrsxXgBJ0QFhMxDAT3Y+MXhjyGNnVK9fe1US07b5EKKrUM/v1EAjBgTQaZ9mI0svJv7Q= X-Received: by 10.223.170.70 with SMTP id q6mr12631226wrd.265.1515450377954; Mon, 08 Jan 2018 14:26:17 -0800 (PST) MIME-Version: 1.0 Received: by 10.223.184.83 with HTTP; Mon, 8 Jan 2018 14:26:17 -0800 (PST) In-Reply-To: <20180108193714.GA15359@savin.petertodd.org> References: <20180108124506.GA13858@savin.petertodd.org> <5c229def-760a-69eb-e646-bd3c77482b00@satoshilabs.com> <20180108193714.GA15359@savin.petertodd.org> From: Ben Kloester Date: Tue, 9 Jan 2018 09:26:17 +1100 Message-ID: To: Peter Todd , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="94eb2c1cc94c73ecb905624b4967" X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Mon, 08 Jan 2018 23:01:51 +0000 Subject: Re: [bitcoin-dev] Satoshilabs secret shared private key scheme X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Jan 2018 22:26:24 -0000 --94eb2c1cc94c73ecb905624b4967 Content-Type: text/plain; charset="UTF-8" > This sounds very dangerous. As Gregory Maxwell pointed out, the key derivation > function is weak enough that passphrases could be easily brute forced So you are essentially imagining that a perpetrator will combine the crypto-nerd fantasy (brute forcing the passphrase) *with* the 5-dollar wrench attack, merging both panes of Randall Munroe's comic? Seems vanishingly unlikely to me - attackers are generally either the wrench type, or the crypto-nerd type. This thread started by you asking Pavol to give an example of a real-life scenario in which this functionality would be used, and your rebuttal is a scenario that is even less likely to occur. "Very dangerous" is a huge stretch. When living in Brazil I often carried two (IRL) wallets - one a decoy to give to muggers, the other with more value stored in it. I heard of plenty of people getting mugged, but I never heard of anyone who gave a decoy wallet getting more thoroughly searched and the second wallet found, despite the relative ease with which a mugger could do this. I'm sure it has happened, probably many times, but point is there is rarely time for contemplation in a shakedown, and most perpetrators will take things at face value and be satisfied with getting something. And searching a physical person's body is a hell of a lot simpler than cracking a passphrase. Moreover, there's no limit to the number of passphrases you can use. If you were an atttacker, at what point would you stop, satisfied? After the first, second, third, fourth wallet that you find/they admit to owning? Going beyond two is already Bond-supervillain level implausible. *Ben Kloester* On 9 January 2018 at 06:37, Peter Todd via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > On Mon, Jan 08, 2018 at 02:00:17PM +0100, Pavol Rusnak wrote: > > On 08/01/18 13:45, Peter Todd wrote: > > > Can you explain _exactly_ what scenario the "plausible deniability" > feature > > > refers to? > > > > > > https://doc.satoshilabs.com/trezor-user/advanced_settings. > html#multi-passphrase-encryption-hidden-wallets > > This sounds very dangerous. As Gregory Maxwell pointed out, the key > derivation > function is weak enough that passphrases could be easily brute forced, at > which > point the bad guys have cryptographic proof that you tried to lie to them > and > cover up funds. > > > What model of human memory are you assuming here? What specifically are you > assuming is easy to remember, and hard to remember? What psychology > research > backs up your assumptions? > > -- > https://petertodd.org 'peter'[:-1]@petertodd.org > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > > --94eb2c1cc94c73ecb905624b4967 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
>=C2=A0This sounds ver= y dangerous. As Gregory Maxwell pointed out, the key derivation
> function is= weak enough that passphrases could be easily brute forced

So you are essentially imagining that a perp= etrator will combine the crypto-nerd fantasy (brute forcing the passphrase)= *with* the 5-dollar wrench attack, merging both panes of Randall Munroe= 9;s comic? Seems vanishingly unlikely to me - attackers=C2=A0are generally = either the wrench type, or the crypto-nerd type.=C2=A0

This thread started by you asking Pavol to give an example of a real-li= fe scenario in which this functionality would be used, and your rebuttal is= a scenario that is even less likely to occur. "Very dangerous" i= s a huge stretch.
When living in Brazil I= often carried two (IRL) wallets - one a decoy to give to muggers, the othe= r with more value stored in it. I heard of plenty of people getting mugged,= but I never heard of anyone who gave a decoy wallet getting more thoroughl= y searched and the second wallet found, despite the relative ease with whic= h a mugger could do this. I'm sure it has happened, probably many times= , but point is there is rarely time for contemplation in a shakedown, and m= ost perpetrators will take things at face value and be satisfied with getti= ng something. And searching a physical person's body is a hell of a lot= simpler than cracking a passphrase.

Moreover, there's no limit = to the number of passphrases you can use. If you were an atttacker, at what= point would you stop, satisfied? After the first, second, third, fourth wa= llet that you find/they admit to owning? Going beyond two is already Bond-s= upervillain level implausible.

Ben Kloester


On 9 January 2018 at 06:37, Peter Todd via b= itcoin-dev <bitcoin-dev@lists.linuxfoundation.org&= gt; wrote:
On Mon= , Jan 08, 2018 at 02:00:17PM +0100, Pavol Rusnak wrote:
> On 08/01/18 13:45, Peter Todd wrote:
> > Can you explain _exactly_ what scenario the "plausible denia= bility" feature
> > refers to?
>
>
> https://doc.satoshilabs.com/trezor-user/advanced_settings.= html#multi-passphrase-encryption-hidden-wallets

This sounds very dangerous. As Gregory Maxwell pointed out, the key = derivation
function is weak enough that passphrases could be easily brute forced, at w= hich
point the bad guys have cryptographic proof that you tried to lie to them a= nd
cover up funds.


What model of human memory are you assuming here? What specifically are you=
assuming is easy to remember, and hard to remember? What psychology researc= h
backs up your assumptions?

--
http= s://petertodd.org 'peter'[:-1]@petertodd.org

_______________________________________________
bitcoin-dev mailing list
bitcoin-dev@lists.= linuxfoundation.org
https://lists.linuxfoundation.org= /mailman/listinfo/bitcoin-dev


--94eb2c1cc94c73ecb905624b4967--