gronager at ceptacle.com
Wed Feb 22 16:29:59 UTC 2012
Hi Gavin / Luke,
BIP-13 again... I started to implement a bitfield based parsing of the version byte using the description I got from Luke, but I then discovered that it does not hold:
00xxxxxx - main network
01xxxxxx - reserved
10xxxxxx - reserved
11xxxxxx - test network
xx00xxxx - bitcoin
xx01xxxx - reserved
xx10xxxx - OTHER (next octet)
xx11xxxx - Namecoin
xxxx000y - PubKeyHash
xxxx001y - reserved
xxxx010y - p2sh
xxxx011y - public key (raw)
xxxx100y - signature
xxxx101y - reserved
xxxx110y - private key (raw)
xxxx111y - OTHER (next octet)
However, the definitions en base58.h are:
PUBKEY_ADDRESS = 0, (00000000)
SCRIPT_ADDRESS = 5, (00000101)
PUBKEY_ADDRESS_TEST = 111, (01101111) !!!
SCRIPT_ADDRESS_TEST = 196, (11000100) !!!
[as a side note litecoin is 48 (00110000) and namecoin is 52 (00110100)]
So there is no logic ?? I have searched the mailing list and the forum for discussions on this but found it hard to find any. If I overlooked something please direct me.
PS: I have said so before, but it would *really* be nice if discussions / conclusions / irc-summaries were taking place at one place - e.g. at the bitcoin-dev mailing list, not at 5-10 different threads in bitcointalk or in bip notes or solely on IRC...
On 20/02/2012, at 18:17, Gavin Andresen wrote:
> > base58-encode: [one-byte network ID][20-byte hash][one-byte address class][3-byte checksum]
> How will the code distinguish between the old scheme:
> and the new?
> 1 in 256 old addresses will have a first-byte-of-checksum that matches the new address class; I guess the code would do something like:
> a) If the 4-byte checksum matches, then assume it is a singlesig address (1 in 2^32 multisig addresses will incorrectly match)
> b) If the one-byte-address-class and 3-byte checksum match, then it is a valid p2sh
> c) Otherwise, invalid address
> The 1 in 2^32 multisig addresses also being valid singlesig addresses makes me think this scheme won't work-- an attacker willing to generate 8 billion or so ECDSA keys could generate a single/multisig collision. I'm not sure how that could be leveraged to their advantage, but I bet they'd find a way.
> RE: should it be a BIP: The BIP process is described in BIP 0001, and you're following it perfectly so far:
> 1) Post a rough draft of the idea here to see if there's any chance it'll be adopted
> 2) Assuming a positive response and no major flaws: write up a draft BIP
> 3) Post the draft BIP here, where it can be picked apart.
> 4) Assuming no major flaws, ask the BIP editor (Amir) for a BIP number
> I'd also encourage you to actually implement your idea between steps 3 and 4. But in this particular case, I think an attacker being able to create singlesig/p2sh address collisions counts as a major flaw.
> Gavin Andresen
Michael Gronager, PhD
Jens Juels Gade 33
2100 Copenhagen E
Mobile: +45 31 45 14 01
E-mail: gronager at ceptacle.com
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