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From: =?UTF-8?Q?Martin_Habov=C5=A1tiak?= <martin.habovstiak@gmail.com>
Date: Fri, 06 Feb 2015 01:50:57 +0100
To: Paul Puey <paul@airbitz.co>, Eric Voskuil <eric@voskuil.org>,
	William Swanson <william@airbitz.co>
Message-ID: <A51A840A-24ED-4FBA-AF23-E820F631280B@gmail.com>
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Proposal for P2P Wireless (Bluetooth LE)
	transfer of Payment URI
Precedence: list

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Commit protocol provides both better user experience and better security.

Dňa 6. februára 2015 1:49:12 CET používateľ Paul Puey <paul@airbitz.co> napísal:
>The trust can be considered bootstrapped by visual verification of the
>address prefix. If we are really concerned about someone jamming a
>Bluetooth signal in a coffeeshop then the UI can encourage verification
>of the prefix. Much like how regular Bluetooth requires 'pairing' via
>entering a 4-6 digit code.
>
>
>
>Paul Puey CEO / Co-Founder, Airbitz Inc
>619.850.8624 | http://airbitz.co | San Diego
>
>
>
>
>On Feb 5, 2015, at 3:46 PM, Eric Voskuil <eric@voskuil.org> wrote:
>
>On 02/05/2015 03:36 PM, MⒶrtin HⒶboⓋštiak wrote:
>>> A BIP-70 signed payment request in the initial broadcast can resolve
>the
>>> integrity issues, but because of the public nature of the broadcast
>>> coupled with strong public identity, the privacy compromise is much
>>> worse. Now transactions are cryptographically tainted.
>>>
>>> This is also the problem with BIP-70 over the web. TLS and other
>>> security precautions aside, an interloper on the communication,
>desktop,
>>> datacenter, etc., can capture payment requests and strongly
>correlate
>>> transactions to identities in an automated manner. The payment
>request
>>> must be kept private between the parties, and that's hard to do.
>>
>> What about using encryption with forward secrecy? Merchant would
>> generate signed request containing public ECDH part, buyer would send
>> back transaction encrypted with ECDH and his public ECDH part. If
>> receiving address/amount is meant to be private, use commit protocol
>> (see ZRTP/RedPhone) and short authentication phrase (which is hard to
>> spoof thanks to commit protocol - see RedPhone)?
>
>Hi Martin,
>
>The problem is that you need to verify the ownership of the public key.
>A MITM can substitute the key. If you don't have verifiable identity
>associated with the public key (PKI/WoT), you need a shared secret
>(such
>as a secret phrase). But the problem is then establishing that secret
>over a public channel.
>
>You can bootstrap a private session over the untrusted network using a
>trusted public key (PKI/WoT). But the presumption is that you are
>already doing this over the web (using TLS). That process is subject to
>attack at the CA. WoT is not subject to a CA attack, because it's
>decentralized. But it's also not sufficiently deployed for some
>scenarios.
>
>e

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