[Bitcoin-development] BIP72 amendment proposal

[Andreas Schildbach]

This is the discussion post corresponding to this PR:
https://github.com/bitcoin/bips/pull/106

"Amend BIP72 by an "h" parameter, which contains a hash of the
PaymentRequest message that is fetched via the "r" parameter.

The hash is meant to link the trust anchor (e.g. the QR code) to the
payment request message in a secure way. This will solve the problem
several apps are comparing address+amount fields as a workaround
instead, preventing some advanced BIP70 usecases. When these apps read a
matching hash, they need not compare any of the other fields.

Thanks to Julian Haight for helping with the standard."