Can you reject or send back bitcoins?

[Calavera]

Do wallets not partition the funds into different bitcoin addresses?  Assuming they keep all of their deposits to hand this would seem like an easy way to manage things.  Even if they don't keep all the deposits, giving each account an expanding unique set of addresses for its external transactions seems wise given the low cost of bitcoin transfers. 

Bitcoin transactions in general do not have a from address. You may derive which addresses its incoming funds passed through, but there may be more than one, and some or all of them could belong to shared accounts. Actually, it's even possible to have no assignable "from" address at all - it's for example possible in the protocol to have a "spend to anyone" transaction, without defined recipient address.

Can you explain further?  I suppose generated coins don't have any sender addresses (looking at the wiki they lack a scriptSig), but regardless of whether a transfer has a recipient for all its input coins it will surely have to have at least one when it makes it into a block (i.e. the block generator). 

[Gavin Andresen]

Do wallets not partition the funds into different bitcoin addresses?

No, they don't.

[theymos]

Can you explain further?  I suppose generated coins don't have any sender addresses (looking at the wiki they lack a scriptSig), but regardless of whether a transfer has a recipient for all its input coins it will surely have to have at least one when it makes it into a block (i.e. the block generator). 

Bitcoin supports a flexible transaction scripting system that could allow you to redeem a transaction without using public/private keys for authentication (using a password, for example). Then there would be no "from" address, as the funds would not have been sent using an address, but with some other method.

[Calavera]

Do wallets not partition the funds into different bitcoin addresses?

No, they don't.

Cheers.  Come to think of it it's unlikely the majority of them will hold a full reserve in the future, whatever they're doing now.

Can you explain further?  I suppose generated coins don't have any sender addresses (looking at the wiki they lack a scriptSig), but regardless of whether a transfer has a recipient for all its input coins it will surely have to have at least one when it makes it into a block (i.e. the block generator). 

Bitcoin supports a flexible transaction scripting system that could allow you to redeem a transaction without using public/private keys for authentication (using a password, for example). Then there would be no "from" address, as the funds would not have been sent using an address, but with some other method.

Okay.  I'm going to have to look further into this.  The transaction system is clearly even more complicated that I had thought. 

[Calavera]

allow you to redeem a transaction without using public/private keys for authentication (using a password, for example).

When you (and the wiki) say "redeem", do you mean "use in another transaction"?

[theymos]

When you (and the wiki) say "redeem", do you mean "use in another transaction"?

Yes. When you redeem a transaction output, you take its coins and use it in another transaction's inputs.

Here's an example of a strange transaction without an automatically-detected address:
http://blockexplorer.com/testnet/tx/64f85bece3a019f452121440b553132e13f6a0daab2664463c122b5e0682047b
In this case, it would be possible to find a valid address from the unusual public key (and if lots of people made these transactions, BBE would do so), but this doesn't always have to be the case.

[Ashpool]

Well thanks for the input.

I am looking at starting a bitcoin related business.  In Australia bitcoins are classed as a non cash payment.  This means there are specific rules around how you handle customer payments.

Generally if you deal with less than $1000 worth per customer you can avoid any financial licensing issues. There are also issues related to your ability to refund unused coins etc. 

Taking on the suggestion that someone must provide a return address before they can deposit funds helps me stay within the local laws.

I can refund money if needed to avoid breach and I have a ready mechanism to return funds.

For those interested in the legal aspects of bitcoins related to Australia see here:
http://www.asic.gov.au/asic/pdflib.nsf/LookupByFileName/ps185.pdf/$file/ps185.pdf

[bitlotto]

Taking on the suggestion that someone must provide a return address before they can deposit funds helps me stay within the local laws.

I can refund money if needed to avoid breach and I have a ready mechanism to return funds.

That will be your best and most reliable method.

[Anonymous]

Well thanks for the input.

I am looking at starting a bitcoin related business.  In Australia bitcoins are classed as a non cash payment.  This means there are specific rules around how you handle customer payments.

Generally if you deal with less than $1000 worth per customer you can avoid any financial licensing issues. There are also issues related to your ability to refund unused coins etc. 

Taking on the suggestion that someone must provide a return address before they can deposit funds helps me stay within the local laws.

I can refund money if needed to avoid breach and I have a ready mechanism to return funds.

For those interested in the legal aspects of bitcoins related to Australia see here:
http://www.asic.gov.au/asic/pdflib.nsf/LookupByFileName/ps185.pdf/$file/ps185.pdf

Any hints on what that business will be ?