- Reset bip-0070/extensions.mediawiki to the original BIP70 contents

- Remove status_code and status_message from individual Payment Protocol messages
- Remove EncryptedInvoiceRequest, EncryptedPaymentRequest, EncryptedPayment and EncryptedPaymentACK messages from protobuf definition file
- Add ProtocolMessageType enum and ProtocolMessageType and EncryptedProtocolMesssage messages to bip-0075/paymentrequest.proto definition file
- Update BIP75 text to remove old individual message encryption paths and include new encapsulating messages for self-contained PaymentProtocol communication (including errors) over various transport layers
- Add initial list of status codes
- Update BIP75 to use AES-256-GCM and remove message hash as GCM mode provides authenticated encryption
- Update ECDH calculation to use SHA256 hash of ECDH's X point instead of the raw X point itself

bip-0070/extensions.mediawiki

@@ -5,7 +5,5 @@ Add your extension below using tags starting at 1000 and submit a pull-req.
 {|
 | Field Number || Extension Name || Field Name || Description
 |-
-| 1000 || [[https://github.com/bitcoin/bips/bip-0075.mediawiki|(BIP75)]] || status_code || Status Code for Payment Protocol error communication
-|-
-| 1001 || [[https://github.com/bitcoin/bips/bip-0075.mediawiki|(BIP75)]] || status_message || Human-readable message for Payment Protocol error communication
+| 1000 || [[https://example.com|(unassigned)]] || (unassigned) || (unassigned)
 |}