From: Jonas Schnelli <dev@jonasschnelli•ch>
To: bitcoin-dev@lists•linuxfoundation.org
Subject: Re: [bitcoin-dev] p2p authentication and encryption BIPs
Date: Wed, 23 Mar 2016 22:55:34 +0100 [thread overview]
Message-ID: <56F310D6.2070002@jonasschnelli.ch> (raw)
In-Reply-To: <1983116.UNQS71VxHo@garp>
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>> I have just PRed a draft version of two BIPs I recently wrote.
>> https://github.com/bitcoin/bips/pull/362
>
> I suggest running a spellchecker ;)
Thanks. Will do.
> * why would you not allow encryption on non-pre-approved connections?
The encryption should be optional.
The proposed authentication scheme does take care of the
identity-management and therefor prevent MITM attacks.
Without the identity management, you might not detect sending/receiving
encrypted data from/to a MITM.
> * we just removed (ssl) encryption from the JSON interface, how do you suggest
> this encryption to be implemented without openSSL?
The proposed encryption schema is based on ECDSA/ECDH (implemented in
libsecp256k1) and AES256CBC (implementation is on the way see
https://github.com/bitcoin/bitcoin/pull/7689).
OpenSSL is not required.
> * What is the reason for using the p2p code to connect a wallet to a node?
> I suggest using one of the other connection methods to connect to the node.
> This avoids a change in the bitcoin protocol for a very specific usecase.
Most known use-case: SPV.
> * Why do you want to do a per-message encryption (wrapping the original)?
> Smaller messages that contain predictable content and are able to be matched
> to the unencrypted versions on the wire send to other nodes will open this
> scheme up to various old statistical attacks.
It's probably extremely inefficient to create a constant time stream.
Even most SSL/SSH application leak information because of the
communication message characteristics.
The current wrapping message proposal is not very efficient.
I will change it so that the p2p message header will contain the
encryption metadata. This should lead to a tiny overhead.
>
>> Responding peers must ignore (banning would lead to fingerprinting) the
> requesting peer after 5 unsuccessfully authentication tries to avoid resource
> attacks.
>
> Any implementation of that kind would itself again be open to resource
> attacks.
> Why 5? Do you want to allow a node to make a typo?
Good point. Maybe one false try should lead to ignoring the peer.
>
>
>> To ensure that no message was dropped or blocked, the complete communication
> must be hashed (sha256). Both peers keep the SHA256 context of the encryption
> session. The complete <code>enc</code> message (leaving out the hash itself)
> must be added to the hash-context by both parties. Before sending a
> <code>enc</code> command, the sha256 context will be copied and finalized.
>
> You write "the complete communication must be hashed" and every message has a
> hash of the state until it is at that point.
> I think you need to explain how that works specifically.
This is a relative simple concept and does not require rehashing the
whole communication. You just append the "new data".
Some pseudocode:
SHA256CTX ctx;
// first com
SHA256CTX_Update(ctx, 1stmessage);
// copy context
SHA256CTX ctxnew = ctx;
// finalize the copied context
sha256hash = SHA256CTX_Finalize(ctxnew); //use as checksum hash
//////// next message
SHA256CTX_Update(ctx, 2ndmessage);
// copy context
SHA256CTX ctxnew = ctx;
// finalize the copied context
sha256hash = SHA256CTX_Finalize(ctxnew); //use as checksum hash
... etc.
</jonas>
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next prev parent reply other threads:[~2016-03-23 21:55 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-23 15:24 Jonas Schnelli
2016-03-23 16:44 ` Tier Nolan
2016-03-23 20:36 ` Tom
2016-03-23 21:40 ` Eric Voskuil
2016-03-23 21:55 ` Jonas Schnelli [this message]
2016-03-25 10:36 ` Tom
2016-03-25 18:43 ` Jonas Schnelli
2016-03-25 20:42 ` Tom
2016-03-26 9:01 ` Jonas Schnelli
2016-03-26 23:23 ` James MacWhyte
2016-03-27 11:58 ` Jonas Schnelli
2016-03-27 17:04 ` James MacWhyte
2016-03-24 0:37 ` Sergio Demian Lerner
2016-03-24 2:16 ` Luke Dashjr
2016-03-24 17:20 ` Chris
2016-03-25 10:41 ` Tom
2016-03-25 7:17 ` Lee Clagett
2016-03-25 10:17 ` Jonas Schnelli
2016-04-01 21:09 ` Jonas Schnelli
2016-04-09 19:40 ` Lee Clagett
2016-05-18 8:00 ` Jonas Schnelli
2016-05-25 0:22 ` Lee Clagett
2016-05-25 9:36 ` Jonas Schnelli
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