How can you trade non integer values of Bitcoin?

[dRic2]

TL;DR Summary

In the original paper 'Bitcoin: A Peer-to-Peer Electronic Cash System', Bitcoin is defined as ''a chain of digital signatures''. Then, how can you trade non integer values?

I don't have any special knowledge about cryptography and these kind of technologies. Also my coding skills are pretty basic, so correct me if I understood wrong.

I was reading the original paper where the idea of Bitcoin is proposed (ref. https://bitcoin.org/bitcoin.pdf). In Sec. 2 (Transaction), first line, we read:

We define an electronic coin as a chain of digital signatures.

The idea is that, we can verify the ''authenticity'' of the coin by looking at the chain of signatures, while cryptography allows us to prevent a malicious attack to easily duplicate the coin (a bit more complicated but, I think that is the bare minimum that I got from the paper).

Every time a transaction takes place, a signature of the last owner is added to the coin. Validation of the transaction then comes with the Proof-of-Work concept but I do not really care about this at the moment.

My question is: if a single Bitcoin is a chain of signatures, and each transactions involving the coin add 1 signature to the string, how does it work if you have non-integer values of the coin?

 

[russ_watters]

Google tells me there's a built-in function to make it divisible to the 8th decimal place. I'm not sure of the technical details, but it would make sense that the register is not an actual coin but rather a list of transactions, it doesn't force you to buy and store integer values; not one copy much less 1,000 copies of the register; that would be pointless.

 

[Vanadium 50]

I don't see why a transaction register needs to work in integers. My checkbook (remember those?) handles 1/100ths of a dollar just fine.

 

[dRic2]

Google tells me there's a built-in function to make it divisible to the 8th decimal place. I'm not sure of the technical details, but it would make sense that the register is not an actual coin but rather a list of transactions, it doesn't force you to buy and store integer values; not one copy much less 1,000 copies of the register; that would be pointless.

Ok, after your suggestion I also found this

How divisible are bitcoins? A bitcoin can be divided down to 8 decimal places. Therefore, 0.00000001 BTC is the smallest amount that can be handled in a transaction. If necessary, the protocol and related software can be modified to handle even smaller amounts.

So, to me, it looks like you are simply re-defining the unit of transactions to be 0.00000001 BTC instead of 1 BTC, right? So the whole protocol has to be thought in terms of this smaller unit.

I don't see why a transaction register needs to work in integers. My checkbook (remember those?) handles 1/100ths of a dollar just fine.

Well, yes, but can you handle transactions of less than a cent ? I think you have to round it up to a cent, therefore making promoting the cent to the be the unit of reference, and not the dollar. Like for Bitcoin, the ''real'' unit seems to be 10^-8 BTC.

 

[Vanadium 50]

Well, yes, but can you handle transactions of less than a cent ?

Why would I want to?

Even in the days of paper money there was a "problem" when splitting a $100 check three ways. We got through that just fine.

 

[dRic2]

Why would I want to?

I was talking about Bitcoin. Since 1BTC ~ 60k $, I was wandering how people make transactions valued less than that. I didn't know how BTC is divided and the paper does not discuss this point. From the definition proposed in the paper it does not seem possible to split a coin, thus my confusion.