300 BTC Coding Contest: Distributed Exchange (MasterCoin Developer Thread)

[Bitoy]

Hi Tachikoma


Buyer 1EdAjiApS5cCpHdH4RKPMab1xmMVRWjLvk posted a
Buy   20 Test MSC for  .00002
TxID: 33644e6f24b29e1ef170d78ff04eab6f7e19368908edc6d477f9902697a71d67

But there is no confirmed payment transaction.   

When buyer posted a sell Transaction (.11 and .9 Test MSC) it is invalid because there was no payment yet for the first transaction.


After reparsing I only found one valid purchase

Buy .2 Test MSC for .003232 BTC
TxID: c7103de53a8ea3a20cec9a74543132f98302f75ab1868092e911dd5516f322a5
Confirm Payment TxID: 2bb54346f7d0ddfcb084451227089665bc1a7ebf8f0a9338d14d713592c268ed

[1714846427]

1714846427

[Bitoy]

Hey Grazcoin,

You'll need to look at your multi-packet handling.  From your de-obfuscated packet It looks like you're SHA hashing the second packet only once.  You'll need to hash seqnum times (so in this case 2).

In terms of a 'definition' for Class B I think the closest thing we have at the mo is my suggested amendment here

Hope that helps

Grazcoin,

You might want to try convert the first hash to uppercase letters before hashing it again.

hashString1 = the first hash string
ex
Dim HashString2 As String = GetHash(hashString1.ToUpper)

This worked for me.

[grazcoin]

Hey Grazcoin,

You'll need to look at your multi-packet handling.  From your de-obfuscated packet It looks like you're SHA hashing the second packet only once.  You'll need to hash seqnum times (so in this case 2).

In terms of a 'definition' for Class B I think the closest thing we have at the mo is my suggested amendment here

Hope that helps

Grazcoin,

You might want to try convert the first hash to uppercase letters before hashing it again.

hashString1 = the first hash string
ex
Dim HashString2 As String = GetHash(hashString1.ToUpper)

This worked for me.

Thanks guys!
That's exactly what I needed

[Tachikoma]

Hi Tachikoma

Buyer 1EdAjiApS5cCpHdH4RKPMab1xmMVRWjLvk posted a
Buy   20 Test MSC for  .00002
TxID: 33644e6f24b29e1ef170d78ff04eab6f7e19368908edc6d477f9902697a71d67

But there is no confirmed payment transaction.   

When buyer posted a sell Transaction (.11 and .9 Test MSC) it is invalid because there was no payment yet for the first transaction.

After reparsing I only found one valid purchase

Buy .2 Test MSC for .003232 BTC
TxID: c7103de53a8ea3a20cec9a74543132f98302f75ab1868092e911dd5516f322a5
Confirm Payment TxID: 2bb54346f7d0ddfcb084451227089665bc1a7ebf8f0a9338d14d713592c268ed

Thanks for checking my data. I'm not sure I understand you correctly though. Could you try explaining it with examples what went wrong?

[grazcoin]

I am adding now the parsing of sell/buy offers to mastercoin-tools, and I start with this tx:
https://blockchain.info/tx/49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34

Code:

$ python msc_parse.py -t 49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34 -d
[D] main: multisig tx found: 49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34
[I] parse_multisig: ['0001000000140000000200000000773594000000000000004e2006000000000000', '000200271000000000000000000000000000000000000000000000000000000000']
[I] parse_multisig: {'tx_hash': '49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34', 'tx_type_str': 'Sell offer', 'formatted_bitcoin_amount_desired': '0.00020000', 'currencyId': '00000002', 'currency_str': 'Test Mastercoin', 'tx_method_str': 'multisig', 'amount': '0000000077359400', 'fee_required': '002710', 'block_time_limit': '06', 'formatted_amount': '20.00000000', 'bitcoin_amount_desired': '0000000000004e20', 'formatted_block_time_limit': '6', 'baseCoin': '00', 'formatted_fee_required': '0.00010000', 'dataSequenceNum': '01', 'transactionType': '00000014'}

I compare to http://mastercoin-explorer.com/transactions/49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34 and it seems that most fields get parsed well, except for:
* Price per coin 0.00001 =>1000 = 0x3E8 ( I don't see any 3e8 on the first or second hexdata)

And I would like to discuss the amount of bytes allocated to each field:
* Bitcoin amount desired - data_script[36:52] (instead of the original "simple send" padding - no problem)
* Fee required - second_data_script[4:10] (limited with 0.16777215 BTC - seems enough)
* Block time limit - data_script[52:54] (limited with 255 blocks which is around 1.77 days - very short)


EDIT:
Price per coin is calculated from "amount" and "bitcoin amount desired".
My only question is not about "block time limit". Isn't it too short?

[zathras]

I am adding now the parsing of sell/buy offers to mastercoin-tools, and I start with this tx:
https://blockchain.info/tx/49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34

Code:

$ python msc_parse.py -t 49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34 -d
[D] main: multisig tx found: 49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34
[I] parse_multisig: ['0001000000140000000200000000773594000000000000004e2006000000000000', '000200271000000000000000000000000000000000000000000000000000000000']
[I] parse_multisig: {'tx_hash': '49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34', 'tx_type_str': 'Sell offer', 'formatted_bitcoin_amount_desired': '0.00020000', 'currencyId': '00000002', 'currency_str': 'Test Mastercoin', 'tx_method_str': 'multisig', 'amount': '0000000077359400', 'fee_required': '002710', 'block_time_limit': '06', 'formatted_amount': '20.00000000', 'bitcoin_amount_desired': '0000000000004e20', 'formatted_block_time_limit': '6', 'baseCoin': '00', 'formatted_fee_required': '0.00010000', 'dataSequenceNum': '01', 'transactionType': '00000014'}

I compare to http://mastercoin-explorer.com/transactions/49f3efe0eba50ea08220c27d3c8174c5fa8a7782615823ab256859562cbd4a34 and it seems that most fields get parsed well, except for:
* Price per coin 0.00001 =>1000 = 0x3E8 ( I don't see any 3e8 on the first or second hexdata)

And I would like to discuss the amount of bytes allocated to each field:
* Bitcoin amount desired - data_script[36:52] (instead of the original "simple send" padding - no problem)
* Fee required - second_data_script[4:10] (limited with 0.16777215 BTC - seems enough)
* Block time limit - data_script[52:54] (limited with 255 blocks which is around 1.77 days - very short)

There is no price per coin in the transaction data, only the number for sale and a total price.  We get price per coin by total price / number for sale.

For the block time limit - this is not how long the sell offer is valid for, it's how long the buyer has to make payment after their accept/'Purchase Offer' is accepted & first in a block.  I don't think too many sellers are going to want to post a sell offer allowing more than 1.77 days for the buyer to make payment During testing between 6 and 10 has been a good value.

[grazcoin]

There is no price per coin in the transaction data, only the number for sale and a total price.  We get price per coin by total price / number for sale.

For the block time limit - this is not how long the sell offer is valid for, it's how long the buyer has to make payment after their accept/'Purchase Offer' is accepted & first in a block.  I don't think too many sellers are going to want to post a sell offer allowing more than 1.77 days for the buyer to make payment During testing between 6 and 10 has been a good value.

Thanks for clarifying.

As I understand the chosen procedure, in order to sell mastercoins, we need 3 tx:
1. Sell offer.
2. Sell accept (that's a better name than purchase offer).
3. Actual payment.

If the buyer doesn't pay within the allowed time, the sell order simply continues (and the next buyer gets the mastercoins).
If there is an earlier buyer (who actually pays) all later accepts are ignored.

[Tachikoma]

There is no price per coin in the transaction data, only the number for sale and a total price.  We get price per coin by total price / number for sale.

For the block time limit - this is not how long the sell offer is valid for, it's how long the buyer has to make payment after their accept/'Purchase Offer' is accepted & first in a block.  I don't think too many sellers are going to want to post a sell offer allowing more than 1.77 days for the buyer to make payment During testing between 6 and 10 has been a good value.

Thanks for clarifying.

As I understand the chosen procedure, in order to sell mastercoins, we need 3 tx:
1. Sell offer.
2. Sell accept (that's a better name than purchase offer).
3. Actual payment.

If the buyer doesn't pay within the allowed time, the sell order simply continues (and the next buyer gets the mastercoins).
If there is an earlier buyer (who actually pays) all later accepts are ignored.

Basically, yes.

Just know that you don't have to buy a whole Purchase Offer in one go. You can just buy a couple of coins which means that the next person buying might also get the coins if there were enough.

[Bitoy]

Hi Tachikoma

Buyer 1EdAjiApS5cCpHdH4RKPMab1xmMVRWjLvk posted a
Buy   
TxID: 33644e6f24b29e1ef170d78ff04eab6f7e19368908edc6d477f9902697a71d67

But there is no confirmed payment transaction.   

When buyer posted a sell Transaction (.11 and .9 Test MSC) it is invalid because there was no payment yet for the first transaction.

After reparsing I only found one valid purchase

Buy .2 Test MSC for .003232 BTC
TxID: c7103de53a8ea3a20cec9a74543132f98302f75ab1868092e911dd5516f322a5
Confirm Payment TxID: 2bb54346f7d0ddfcb084451227089665bc1a7ebf8f0a9338d14d713592c268ed

Thanks for checking my data. I'm not sure I understand you correctly though. Could you try explaining it with examples what went wrong?

I can't find the transaction where    
1EdAjiApS5cCpHdH4RKPMab1xmMVRWjLvk sent  .00002 BTC to  16rAwebBXhJAM9ALf3fLFbaHKz24r2o3UN
If there is a payment the rest of the transaction will be valid.   It could be a bug in my implementation.

Here is an example
UserA places an advertisement to sell
UserB accepts UserA's  offer
(Note: UserB has not paid UserA)

UserB places an advertisement to sell
UserC accepts UserB's offer
UserC pays UserB


Since UserB has not paid UserA the transaction of UserB with UserC is invalid.

[prophetx]

Offer cancellation

Is there something for this, to pull back an offer?  Maybe I missed it.  Or would one need to accept ones own offer in orer to cancel it it out once the offer hits the blockchain?

[Tachikoma]

Offer cancellation

Is there something for this, to pull back an offer?  Maybe I missed it.  Or would one need to accept ones own offer in orer to cancel it it out once the offer hits the blockchain?

Make a new Selling Offer and set the amount to zero

[Tachikoma]

Hi Tachikoma

Buyer 1EdAjiApS5cCpHdH4RKPMab1xmMVRWjLvk posted a
Buy   
TxID: 33644e6f24b29e1ef170d78ff04eab6f7e19368908edc6d477f9902697a71d67

But there is no confirmed payment transaction.   

When buyer posted a sell Transaction (.11 and .9 Test MSC) it is invalid because there was no payment yet for the first transaction.

After reparsing I only found one valid purchase

Buy .2 Test MSC for .003232 BTC
TxID: c7103de53a8ea3a20cec9a74543132f98302f75ab1868092e911dd5516f322a5
Confirm Payment TxID: 2bb54346f7d0ddfcb084451227089665bc1a7ebf8f0a9338d14d713592c268ed

Thanks for checking my data. I'm not sure I understand you correctly though. Could you try explaining it with examples what went wrong?

I can't find the transaction where    
1EdAjiApS5cCpHdH4RKPMab1xmMVRWjLvk sent  .00002 BTC to  16rAwebBXhJAM9ALf3fLFbaHKz24r2o3UN
If there is a payment the rest of the transaction will be valid.   It could be a bug in my implementation.

Here is an example
UserA places an advertisement to sell
UserB accepts UserA's  offer
(Note: UserB has not paid UserA)

UserB places an advertisement to sell
UserC accepts UserB's offer
UserC pays UserB


Since UserB has not paid UserA the transaction of UserB with UserC is invalid.

Hmm, I'm afraid that perhaps my implementation actually counts the "Purchase Offer" as the actual payment. Since the amounts are so small it might have considered the output amount of the Mastercoin payment as payment since we use the reference address. Normally this shouldn't happen since the amounts will be much larger. I will check my code to see how it matches based on block number.

[prophetx]

Offer cancellation

Is there something for this, to pull back an offer?  Maybe I missed it.  Or would one need to accept ones own offer in orer to cancel it it out once the offer hits the blockchain?

Make a new Selling Offer and set the amount to zero

Is that always the case?

So one could not have 2 sell offers say at different prices from the same address?  Each consequetive offer replaces the prior? 

For example, I have 100 msc, and put an offer to sell 50 at 1 btc each.

If I want to cancel this then I would make another offer for 0 at x btc.

But that precludes being able to have one offer of 50 msc at 1 btc each and another offer at 50 msc at 0.9 btc each.  Unless I move 50 msc to another address first.

I guess I need to read the spec again.

[Tachikoma]

You can only have one offer per address. Reading the paper will make this clear. You can easily have multiple addresses though, so it doesn't have to be a real problem.

[Tachikoma]

After reparsing I only found one valid purchase

Buy .2 Test MSC for .003232 BTC
TxID: c7103de53a8ea3a20cec9a74543132f98302f75ab1868092e911dd5516f322a5
Confirm Payment TxID: 2bb54346f7d0ddfcb084451227089665bc1a7ebf8f0a9338d14d713592c268ed

Looks like this transaction also didn't pass

The payment was made after the Max Block Limit of 267486.

Transaction is also invalid. 

I don't think so. The payment was one block later then the "Purchase Offer"

[Bitoy]

After reparsing I only found one valid purchase

Buy .2 Test MSC for .003232 BTC
TxID: c7103de53a8ea3a20cec9a74543132f98302f75ab1868092e911dd5516f322a5
Confirm Payment TxID: 2bb54346f7d0ddfcb084451227089665bc1a7ebf8f0a9338d14d713592c268ed

Looks like this transaction also didn't pass

The payment was made after the Max Block Limit of 267486.

Transaction is also invalid. 

I don't think so. The payment was one block later then the "Purchase Offer"

You are correct.   Payment is before block limit of 267486.   Site updated.  Thanks =)

http://mymastercoins.com/Orders.aspx?CurrencyID=2

[ASIC-8Tile]

Please PM me if SOMEONE has extra Test Mastercoins they can spare...

[Tachikoma]

Please PM me if SOMEONE has extra Test Mastercoins they can spare...

Give me an address and I will send you some.

[4nil]

I was wondering, would it be possible to build upon the same mechanism for BTC-MSC exchange and add support for LTC/other alt-chain exchanging? I don't use LTC or have any but I do know a decent segment would find it useful to be able to trade back and forth between alt currencies. It could be a good, quick, and easy proof-of-concept and validation for Mastercoin to be used to trade other cryptocurrencies around for each other if there was a way to parse/manipulate two blockchains at once.

Actually thinking about it, it probably would be trivial. If you can do it with BTC I don't see why LTC would be difficult but I'm not an expert.

I think once MSC to BTC is working then LTC and the other altcoins ought to be next.

LTC will have to wait until we've got LTC tokens stored in the bitcoin block chain. That will either be user-backed smart property, or escrow-backed tokens later. We can do BTC/MSC now because we are living in the BTC block chain.

i'm new to MSC, when i finished reading your spec i got one question,
why not issue MSC as smart property at the very beginning of genesis block rather than sending people MSC from your account.
with my understanding, it could be 2 steps.
1. issue smart property.
2. selling part of shares to raise money.
is it possible to create MSC as the first smart property in MSC protocol?

[4nil]

Please PM me if SOMEONE has extra Test Mastercoins they can spare...

Give me an address and I will send you some.

i've tried bitcoin-qt to finish a offer, finally failed
could you send me some for test, my address: 14niL1KeoNafvXYzcn9Win7avBkXQ7U2g2, thanks.