WIP: Support different initial packet filler

All-zero initial packets should only be used for generating
test vectors because of possible privacy leak.
"Create packet (reference test vector)" testcase updated to
new testcases provided by the RFC repo to meet this change
of spec.

See more:
lightning/bolts@8dd0b75
https://github.com/lightningnetwork/lightning-rfc/blob/master/04-onion-routing.md#packet-construction

src/DotNetLightning.Core/Crypto/Sphinx.fs

@@ -194,22 +194,36 @@ module Sphinx =
                               HMAC = nextHmac }
             nextPacket
 
+    module PacketFiller =
+        // DeterministicPacketFiller is a packet filler that generates a deterministic
+        // set of filler bytes by using chacha20 with a key derived from the session
+        // key.
+        let DeterministicPacketFiller (sessionKey: Key) =
+            generateStream(generateKey("pad",sessionKey.ToBytes()), 1300)
+
+        // BlankPacketFiller is a packet filler that doesn't attempt to fill out the
+        // packet at all. It should ONLY be used for generating test vectors or other
+        // instances that required deterministic packet generation.
+        [<Obsolete("BlankPacketFiller is obsolete, see here: https://github.com/lightningnetwork/lightning-rfc/commit/8dd0b75809c9a7498bb9031a6674e5f58db509f4", false)>]
+        let BlankPacketFiller _=
+            Array.zeroCreate 1300
+
     type PacketAndSecrets = {
         Packet: OnionPacket
         /// Shared secrets (one per node in the route). Known (and needed) only if you're creating the
         /// packet. Empty if you're just forwarding the packet to the next node
         SharedSecrets: (Key * PubKey) list
     }
         with
-            static member Create (sessionKey: Key, pubKeys: PubKey list, payloads: byte[] list, ad: byte[]) =
+            static member Create (sessionKey: Key, pubKeys: PubKey list, payloads: byte[] list, ad: byte[], initialPacketFiller: Key -> byte[]) =
                 let (ephemeralPubKeys, sharedSecrets) = computeEphemeralPublicKeysAndSharedSecrets (sessionKey) (pubKeys)
                 let filler = generateFiller "rho" payloads sharedSecrets
 
                 let lastPacket = makeNextPacket(payloads |> List.last,
                                                 ad,
                                                 ephemeralPubKeys |> List.last,
                                                 (sharedSecrets |> List.last |> fun ss -> ss.ToBytes()),
-                                                OnionPacket.LastPacket,
+                                                {OnionPacket.LastPacket with HopData = initialPacketFiller(sessionKey)},
                                                 Some(filler))
                 let rec loop (hopPayloads: byte[] list, ephKeys: PubKey list, ss: Key list, packet: OnionPacket) =
                     if (hopPayloads.IsEmpty) then

tests/DotNetLightning.Core.Tests/SphinxTests.fs

@@ -30,10 +30,10 @@ let expectedPubKeys = [ "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea
                       |> List.map(hex.DecodeData >> PubKey)
 
 let payloads = [ "000000000000000000000000000000000000000000000000000000000000000000"
-                 "000101010101010101000000010000000100000000000000000000000000000000"
-                 "000202020202020202000000020000000200000000000000000000000000000000"
-                 "000303030303030303000000030000000300000000000000000000000000000000"
-                 "000404040404040404000000040000000400000000000000000000000000000000" ]
+                 "000101010101010101000000000000000100000001000000000000000000000000"
+                 "000202020202020202000000000000000200000002000000000000000000000000"
+                 "000303030303030303000000000000000300000003000000000000000000000000"
+                 "000404040404040404000000000000000400000004000000000000000000000000" ]
                |> List.map(hex.DecodeData)
 
 let associatedData = "4242424242424242424242424242424242424242424242424242424242424242" |> hex.DecodeData
@@ -73,10 +73,10 @@ let bolt4Tests1 =
 
         testCase "Create packet (reference test vector)" <| fun _ ->
             let (onion, _ss) =
-                let p = PacketAndSecrets.Create (sessionKey, pubKeys, payloads, associatedData)
+                let p = PacketAndSecrets.Create (sessionKey, pubKeys, payloads, associatedData, PacketFiller.DeterministicPacketFiller)
                 (p.Packet, p.SharedSecrets)
             let expectedPacket =
-                "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"
+                "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"
                 |> hex.DecodeData
             CheckArrayEqual (onion.ToBytes()) (expectedPacket)
             let { Payload = payload0; NextPacket = nextPacket0; SharedSecret = _ss0 }: ParsedPacket =
@@ -99,16 +99,16 @@ let bolt4Tests1 =
 
             Expect.equal [payload0; payload1; payload2; payload3; payload4] payloads ""
 
-            Expect.equal nextPacket0.HMAC ("2bdc5227c8eb8ba5fcfc15cfc2aa578ff208c106646d0652cd289c0a37e445bb" |> hex.DecodeData |> uint256) ""
-            Expect.equal nextPacket1.HMAC ("28430b210c0af631ef80dc8594c08557ce4626bdd3593314624a588cc083a1d9" |> hex.DecodeData |> uint256) ""
-            Expect.equal nextPacket2.HMAC ("4e888d0cc6a90e7f857af18ac858834ac251d0d1c196d198df48a0c5bf816803" |> hex.DecodeData |> uint256) ""
-            Expect.equal nextPacket3.HMAC ("42c10947e06bda75b35ac2a9e38005479a6feac51468712e751c71a1dcf3e31b" |> hex.DecodeData |> uint256) ""
+            Expect.equal nextPacket0.HMAC ("a93aa4f40241cef3e764e24b28570a0db39af82ab5102c3a04e51bec8cca9394" |> hex.DecodeData |> uint256) ""
+            Expect.equal nextPacket1.HMAC ("5d1b11f1efeaa9be32eb1c74b113c0b46f056bb49e2a35a51ceaece6bd31332c" |> hex.DecodeData |> uint256) ""
+            Expect.equal nextPacket2.HMAC ("19ca6357b5552b28e50ae226854eec874bbbf7025cf290a34c06b4eff5d2bac0" |> hex.DecodeData |> uint256) ""
+            Expect.equal nextPacket3.HMAC ("16d4553c6084b369073d259381bb5b02c16bb2c590bbd9e69346cf7ebd563229" |> hex.DecodeData |> uint256) ""
             Expect.equal nextPacket4.HMAC ("0000000000000000000000000000000000000000000000000000000000000000" |> hex.DecodeData |> uint256) ""
             ()
 
         testCase "last node replies with an error message" <| fun _ ->
             let (onion, ss) =
-                let p = PacketAndSecrets.Create (sessionKey, pubKeys, payloads, associatedData)
+                let p = PacketAndSecrets.Create (sessionKey, pubKeys, payloads, associatedData, PacketFiller.BlankPacketFiller)
                 (p.Packet, p.SharedSecrets)
             let { NextPacket = packet1; SharedSecret = ss0 }: ParsedPacket =
                 Sphinx.parsePacket (privKeys.[0]) (associatedData) (onion.ToBytes())
@@ -166,7 +166,7 @@ let bolt4Tests1 =
 
         testCase "Intermediate node replies with an error message" <| fun _ ->
             let { Packet = packet; SharedSecrets = ss } =
-                Sphinx.PacketAndSecrets.Create(sessionKey, pubKeys, payloads, associatedData)
+                Sphinx.PacketAndSecrets.Create(sessionKey, pubKeys, payloads, associatedData, PacketFiller.BlankPacketFiller)
             let { NextPacket = packet1; SharedSecret = ss0 } =
                 Sphinx.parsePacket(privKeys.[0]) (associatedData) (packet.ToBytes())
                 |> Result.defaultWith(fun _ -> failwith "Fail: bolt4 intrm node replies with err msg defaultClosure0")