Subject: Re: [bitcoin-dev] [BIP Draft] Datastream compression of Blocks and Transactions

From: Patrick Strateman <[email-masked]>
Date: Wed, 02 Dec 2015 10:45:23 -0800

If compression is to be used a custom compression algorithm should be
written.

Bitcoin data is largely incompressible outside of a tiny subset of fields.

On 12/01/2015 11:33 PM, Simon Liu via bitcoin-dev wrote:
> Hi Pavel,
>
> (my earlier email was moderated, so the list can only see it via your
> reply),
>
> Yes, an attacker could try and send malicious data to take advantage of
> a compression library vulnerability...  but is it that much worse than
> existing attack vectors which might also result in denial of service,
> crashes, remote execution?
>
> Peter, perhaps your BIP can look at possible ways to isolate the
> decompression phase, such as having incoming compressed blocks be saved
> to a quarantine folder and an external process/daemon decompress and
> verify the block's hash?
>
> Regards,
> Simon
>
>
> On 12/01/2015 10:47 PM, Pavel Janík wrote:
>>> On 02 Dec 2015, at 00:44, Simon Liu <[email-masked]> wrote:
>>>
>>> Hi Matt/Pavel,
>>>
>>> Why is it scary/undesirable?  Thanks.
>> Select your preferable compression library and google for it with +CVE.
>>
>> E.g. in zlib:
>>
>> http://www.cvedetails.com/vulnerability-list/vendor_id-72/product_id-1820/GNU-Zlib.html
>>
>> …allows remote attackers to cause a denial of service (crash) via a crafted compressed stream…
>> …allows remote attackers to cause a denial of service (application crash)…
>> etc.
>>
>> Do you want to expose such lib to the potential attacker?
>> --  
>> Pavel Janík
>>
>>
>>
>>
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