Allow a channel re-open or a new channel to be created after a close

[hackaugusto]

Remove the channel address from the manager once the channel is settled is a possible solution, this allows a new contract to be created.

[czepluch]

Should this happen right after settle is called?

[hackaugusto]

I think so, the users will need to wait for settleTimeout until that can happen, but we don't lose the address from the channel manager (it is useful for third-parties calling unlock and/or updating the transfers)

[czepluch]

Also clean up the BC when a channel is settled by calling suicide

[czepluch]

If we're planning on making changes to the messages anyway, we might as well add channel_address to the messages, and use this as an identifier to prevent double spending.

[heikoheiko]

I'm strongly against adding another field to the message (making it longer) unless necessary.

There are two alternative ways of solving the problem:

1. hash the channel_address into the signature. That is sign sha3(msg+channel_address).
2. Use nonce ranges. I.e. the starting nonce could be block.number * 2^192

I'm in favor of 2)

[czepluch]

I agree 2) is the best solution.

I will however need to change the messages to change the length of the nonce. Right now it's only 8 bytes and I think that's not quite enough. @hackaugusto you see any problems with this?

[hackaugusto]

Increasing the nonce field seems backwards, after all the decision to not add a new field is to not increase the message size.

Why not go with option 1?

[czepluch]

Valid point. If we try to avoid increasing the size of the messages, then it makes more sense to go with option 1.

[heikoheiko]

how is 8 bytes not enough? 4bytes for all possible block offsets during the next 100 years and 4 billion transfers during the lifetime of the channels sounds good to me.

[heikoheiko]

my assumption would be that hashing in the address of the contract might be more changes to the code base. but no strong preferences.

[czepluch]

This issue is very close to being done. PR will be submitted tomorrow.