Signature alone is not enough to identify signed data

[pirapira]

but if we identify the signature and the signer, we can also identify the signed content.

What this PR does

This PR adds non_closing_address and token_network_address in RewardProofs.

Why I'm making this PR

RewardProof contained a signature non_closing_signature and we relied on that to specify a call. However, when somebody changes the signed data, our signature verification algorithm just emits a different address. So a signature alone was not enough to specify a byte blob. We need the signer's address.

Even when we can identify a byte blob, the same byte blob means different things on different token_network_address. So token_network_address is also added in the reward proof.

What's tricky about this PR (if any)

We use a signature system to establish the integrity of (token_network_address, sig, address). Within token_network_address we use the signature system again on sig, address. So the reasoning is a bit complicated.

I expect the CI to fail now, but I'm seeking feedbacks now.

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Any reviewer can check these:

• If the PR is fixing a bug or adding a feature, add an entry to CHANGELOG.md.
• If the PR changed a Solidity source, run make compile_contracts and add the resulting raiden_contracts/data/contracts.json in the PR.
• If the PR is changing documentation only, add [skip ci] in the commit message so Travis does not waste time.
  • But, if the PR changes comments in a Solidity source, do not add [skip ci] and let Travis check the hash of the source.
• In Python, use keyword arguments
• Squash unnecessary commits
• Comment commits
• Follow naming conventions
  • solidityFunction
  • _solidity_argument
  • solidity_variable
  • python_variable
  • PYTHON_CONSTANT
• Follow the Signature Convention in CONTRIBUTING.md
• For each new contract
  • The deployment script deploys the new contract.
  • etherscan_verify.py runs on the new contract.
• Bookkeep
  • The gas cost of new functions are stored in gas.json.
• Solidity specific conventions
  • Document arguments of functions in natspec
  • Care reentrancy problems
• When you catch a require() failure in Solidity, look for a specific error message like pytest.raises(TransactionFailed, match="error message"):

And before "merge" all checkboxes have to be checked. If you find redundant points, remove them.

[codecov]

Codecov Report

Merging #1238 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1238   +/-   ##
=======================================
  Coverage   81.28%   81.28%           
=======================================
  Files          21       21           
  Lines        1453     1453           
  Branches      190      190           
=======================================
  Hits         1181     1181           
  Misses        231      231           
  Partials       41       41

Impacted Files	Coverage Δ
raiden_contracts/utils/proofs.py	92.3% <ø> (ø)	⬆️

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[rakanalh]

LGTM