I’d like to take advantage of the immutability and nonrepudiable nature of the blockchain.
Let’s say I enter into a bet with my friend that if it rains 10 days from now, I will pay him $100. If it doesn’t, he will pay me $100. In the real world, we would draft a paper agreement which both of us sign physically as proof.
How can this be done in the Ethereum world without involving the use of Ether? (except to pay for gas of course, we like betting with cash ;-) Can Ethereum be used to prove both of us entered into an agreement 10 days earlier? E.g. by storing in the blockchain the digital signatures of us signing a PDF agreement and saving such document on IPFS?