Reveal R mechanism

[vkuznecovas]

At the moment, R's are only revealed for ongoing sessions.

This, however, is fragile as R's are only revealed when the consumer is connected to us. If we want a more resilient mechanism, a job should start when providing a service and periodically check for promises that might need to be revealed and revealing them.

The session pingpong would then also need to be redesigned a little to make the synchronous calls to accountant obsolete.

[vkuznecovas]

This also needs to keep in mind the possibility of hashlock missmatches between provider and accountant.

[zolia]

We had a grooming session with @vkuznecovas today. My suggestion is to store encrypted R on Accountant:

• Loss of R looks like a major issue which forces provider to create a new identity. We want to avoid that.
• We already manage state on Accountant and assume that it cannot be lost.
• Provider with request_promise message would send its R encrypted with its own private key.
• Ability to fetch encrypted R also enables synchronization between concurrent request_promise messages since Provider will not exactly which R is to be expected by Accountant.

@chompomonim can you comment on such solution? Should we proceed?

[chompomonim]

I think this solution could work. Using an Accountant as your backup service (for R in encrypted form) looks quite interesting.

[chompomonim]

I suppose this error is related?

Mar 11 10:10:59 myst-2 myst[16462]: 2020-03-11T10:10:59.718 INF market/mysterium/mysterium_api.go:203    > Proposal pinged for node: 0x9137cbfb964275623121385ecb951e484de5f964 service type: wireguard
Mar 11 10:10:59 myst-2 myst[16462]: 2020-03-11T10:10:59.750 DBG session/pingpong/price_calculator.go:66  > Calculated price 52541. Time component: 51866, data component: 675
Mar 11 10:10:59 myst-2 myst[16462]: 2020-03-11T10:10:59.927 DBG communication/nats/sender.go:60          > Message "bba904cd-3227-4c36-907c-d81facdeb8d6.session-invoice" sending: {"payload":{"invoice":{"AgreementID":2619551165047835842,"AgreementTotal":52541,"TransactorFee":0,"Hashlock":"fe0ee7140cd1094052a6fc4e89c1ad13eed61b4d8f187e457add0debad789d1c","Provider":"0x9137cbfb964275623121385ecb951e484de5f964"}},"signature":"NThk3E9akWV3AyBkEC+TTh2Xe8oD4GzqXrG5MsLzHAVgDG+ryxnOFnTJQUJSwjBP9O5kqhuiFxsR+TGy0LnNlQA="}
Mar 11 10:11:01 myst-2 myst[16462]: 2020-03-11T10:11:01.276 INF market/mysterium/mysterium_api.go:203    > Proposal pinged for node: 0x9137cbfb964275623121385ecb951e484de5f964 service type: openvpn
Mar 11 10:11:01 myst-2 myst[16462]: 2020-03-11T10:11:01.996 DBG communication/nats/receiver.go:54        > Message "bba904cd-3227-4c36-907c-d81facdeb8d6.session-exchange" received: {"payload":{"exchangeMessage":{"Promise":{"ChannelID":"roW10++JHEW7CxG8Ng3Vqev4STs=","Amount":969530677,"Fee":0,"Hashlock":"/g7nFAzRCUBSpvxOicGtE+7WG02PGH5Fet0N6614nRw=","R":null,"Signature":"ltbZevDn2MaJ7ITfN1PDegqiS8nn63ybLR+UIHhWqRNCildR23jhnf2cMyurUNEJDuN2PUm6JYILmeKxAtMweBs="},"AgreementID":2619551165047835842,"AgreementTotal":52541,"Provider":"0x9137cbfb964275623121385ecb951e484de5f964","Signature":"bd3e7117f6a29019e8745a3b83c29325b38fa7d89a42ab3d9fb99774e8a41c060d9bd2262d6cc3662de3c982b9905c7a60acaea56f086da75d71320c78a71a761c"}},"signature":"PKyxHW6beqhtKkl7xYN6URvW1733D+rudc198TONHcwXcg8T1n//Fhx3+qQ8GRwmatmn1dlgqXWWlr5TKPTwjQA="}
Mar 11 10:11:02 myst-2 myst[16462]: 2020-03-11T10:11:02.353 WRN session/pingpong/invoice_tracker.go:510  > accountant error, will retry error="could not request promise: Secret R for previous promise exchange (Hashlock: \"bd6c946b12b0791ff9d302b3948f4e6fc2053972c73d40f93915f0056ebad073\") was not revealed: previous R not revealed: previous R not revealed"