Does the chainstate leveldb only contain "addresses" for P2PKH and P2SH?

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I'm writing a small script that will dump the utxo database to a text file. As far as I'm aware, these are the most common script patterns indicated by the type field inside each value:

e.g. value:    b98276a2ec7700cbc2986ff9aed6825920aece14aa6f5382ca5580
               <----><----><><-------------------------------------->
                /      /    \                   \
 height/coinbase  value      type                script data


0x00 = P2PKH (hash160 public key)
0x01 = P2SH  (hash160 script)
0x02 = P2PK
0x03 = P2PK
0x04 = P2PK (uncompressed)
0x05 = P2PK (uncompressed)

It seems as though the script type is there so that you only need to store the minimal amount of script data inside the database (e.g. the unique public keys and script hashes inside P2PK, P2PKH, and P2SH).

Anyway, would I be correct in assuming that you could only get an address from script types 0 and 1 (by base58 encoding the script data)?

In other words, the chainstate leveldb does not include any witness data to allow you get addresses for utxos using P2WPKH and P2WSH scripts?

EDIT: Here's the finished tool: https://github.com/in3rsha/bitcoin-utxo-dump

inersha

Posted 2019-03-29T09:56:52.107

Reputation: 2 236

Answers

3

Yes, Bitcoin Core does do some compression of standard output scripts in order to store the minimal amount of data needed.

Anyway, would I be correct in assuming that you could only get an address from script types 0 and 1 (by base58 encoding the script data)?

Yes

In other words, the chainstate leveldb does not include any witness data to allow you get addresses for utxos using P2WPKH and P2WSH scripts?

If by witness data you mean Segwit outputs, no. ALL output's scriptPubKeys are stored in the database, otherwise it would be unable to verify transactions that spend arbitrary scripts and segwit scripts. These scripts are stored without special compression (i.e. the type stuff going on here) and just serialized as is. Segwit outputs are already in a minimal form so there is no need for a type here.

Since all scriptPubKeys are stored in the database, you can compute the address for every UTXO if it has one, including segwit UTXOs.

Also, the term witness data refers to the signatures and input data for a transaction that spends a segwit output. It does not refer to anything that is segwit related. Using the term "witness data" in your question is confusing.

Andrew Chow

Posted 2019-03-29T09:56:52.107

Reputation: 40 910

Ha, had the completely the wrong idea with where I was going there. Thanks for clearing that up. – inersha – 2019-03-29T18:52:25.013

Seeing as P2WPKH and P2WSH scripts are stored without special compression, what does the script type field indicate for these entries? From a quick look it appears that P2WPKH are type 28 and P2WSH are type 40. I'm not sure what the number indicates when it's greater than 5. – inersha – 2019-03-30T11:35:51.113

It seems as though if the type is greater than 5, then it indicates the size of the upcoming script. Although the size given is actually 6 bytes greater, so you should subtract 6 to get the actual size of the upcoming script. – inersha – 2019-03-30T12:09:35.583

A brief description of the compression can be found here: https://github.com/bitcoin/bitcoin/blob/master/src/compressor.h#L25. There are only 6 types, 0x00 is P2PKH, 0x01 is P2SH, 0x02 and 0x03 are compressed pubkeys. Those bytes are actually part of the pubkey itself. 0x04 and 0x05 are uncompressed pubkeys. After that, the first byte is the script size + 6, so the real size is byte - 6.

– Andrew Chow – 2019-03-30T16:11:46.167

Thank you. Why is it that 0x05 is used for uncompressed public keys, seeing as they always start with 0x04? Why not just use 0x04 for all uncompressed public keys? – inersha – 2019-03-30T16:17:59.603

The uncompressed pubkeys are compressed when they are added to the db. 0x04 and 0x05 are used to indicate that the key is supposed to be uncompressed and those indicate whether the y value is even or odd so that the full uncompressed key can be retrieved. It's basically the same thing as for normal pubkey compression, just with different values to indicate that the script uses an uncompressed key and not a compressed one. – Andrew Chow – 2019-03-30T19:14:21.290

Gotcha, thank you very much, you have explained everything! – inersha – 2019-03-30T19:28:56.183

Asked: 2019-03-29T09:56:52.107

Viewed: 81 times

Active: 2019-04-21T16:23:35.213