Sustainable nanopayment idea: Probabilistic Payments

[casascius]

Just realized the setup would have to be performed for each nanopayment. Your 1 in 10000 chance becomes a 1 in 9999 chance after one choice is eliminated. Repeat that 5000 times and you're paying twice what you should be. Not necessarily a big deal if the setup is embedded into the communication about the service bought with the payment to avoid extra round trips.

Repeat it 5000 times to the same merchant in a short period of time and you're probably consuming enough that a nanopayment no longer makes sense.  Just pay 0.5 BTC to the intended recipient the normal way.  This is intended as a way for moneybees to casually and anonymously pay for bits of pollen from lots of payflowers without burdening the block chain with dust spam - not so much for people to buy a jar of honey.

[DeepBit]

When Alice sends a share to Bob, she signs a transaction that looks like this:  OP_DUP OP_HASH160 <bobs-address> OP_EQUALVERIFY OP_2DUP OP_CHECKSIGVERIFY OP_HASH160 OP_SWAP OP_HASH160 OP_XOR <constant:10000> OP_MOD OP_0 OP_EQUAL

NOW, HOW ON EARTH DOES THAT SCRIPT SOUP WORK?

At least not as intended :)

Sadly most opcodes are crippled, disabled or useless. For example, math opcodes can only work on 4-byte numbers, so 160-bit hashes won't give the result you are expecting.

[phelix]

I think there's a simpler way that only needs standard transactions and works with the network as-is. I wrote it up in a wiki article:
https://en.bitcoin.it/wiki/Nanopayments

In a nutshell... Bob makes a secret transaction. He tells Alice the hash is in a certain range and Alice tries to guess its hash. Her transaction depends on Bob's, so if she guesses wrong, her transaction is invalid for spending a nonexistent transaction.

This sounds really good. Would any of the suggested methods actually work?

[hi-entropy]

phelix, I'm pretty sure that jevon's idea works as-is. I wrote a sample implementation in Node: https://github.com/hi-entropy/bitcoin-nanopayment

[phelix]

phelix, I'm pretty sure that jevon's idea works as-is. I wrote a sample implementation in Node: https://github.com/hi-entropy/bitcoin-nanopayment

Nice!

Each payment requires two transactions (hence double the transaction fee)

I assume you mean "each actual payment"?

[hi-entropy]

Each payment requires two transactions (hence double the transaction fee)

I assume you mean "each actual payment"?

Right, I meant that each interaction that results in a payment going through actually consists of two transactions. I'll try to figure out a better way to word that.