encoding: introducing the "nop" cipher

remove encryption for faster large scale tests.
Do not use for anything else!

Signed-off-by: Csaba Kiraly <csaba.kiraly@gmail.com>

libp2pdht/private/eth/p2p/discoveryv5/encoding.nim

@@ -24,6 +24,7 @@ import
   libp2p/signed_envelope,
   metrics,
   nimcrypto,
+  nop,
   "."/[messages, messages_encoding, node, spr, hkdf, sessions],
   "."/crypto
 
@@ -40,7 +41,7 @@ logScope:
   topics = "discv5"
 
 type
-  cipher = aes128
+  cipher = nop128
 
 const
   version: uint16 = 1

libp2pdht/private/eth/p2p/discoveryv5/nop.nim

@@ -0,0 +1,74 @@
+#
+#
+#                    NimCrypto
+#        (c) Copyright 2023 Status
+#
+#      See the file "LICENSE", included in this
+#    distribution, for details about the copyright.
+#
+
+## This module implements a no-op(NOP) crypto that des nothing,
+## Do not use for anything else than testing.
+
+{.deadCodeElim:on.}
+
+when sizeof(int) == 4:
+  type
+    NopContext[bits: static[uint]] = object
+      skey: array[120, uint32]
+      nr: int
+elif sizeof(int) == 8:
+  type
+    NopContext[bits: static[uint]] = object
+      skey: array[120, uint64]
+      nr: int
+
+type
+  nop128* = NopContext[128]
+  nop192* = NopContext[192]
+  nop256* = NopContext[256]
+  nop* = nop128 | nop192 | nop256
+
+proc encrypt*(ctx: NopContext, input: openarray[byte],
+              output: var openarray[byte]) =
+  for i, v in input:
+    output[i] = v
+
+proc decrypt*(ctx: NopContext, input: openarray[byte],
+              output: var openarray[byte]) =
+  for i, v in input:
+    output[i] = v
+
+template sizeKey*(ctx: NopContext): int =
+  (ctx.bits div 8)
+
+template sizeBlock*(ctx: NopContext): int =
+  (16)
+
+template sizeKey*(r: typedesc[nop]): int =
+  when r is nop128:
+    (16)
+  elif r is nop192:
+    (24)
+  elif r is nop256:
+    (32)
+
+template sizeBlock*(r: typedesc[nop]): int =
+  (16)
+
+proc init*(ctx: var NopContext, key: openarray[byte]) {.inline.} =
+  discard
+
+proc init*(ctx: var NopContext, key: ptr byte, nkey: int = 0) {.inline.} =
+  discard
+
+proc clear*(ctx: var NopContext) {.inline.} =
+  discard
+
+proc encrypt*(ctx: var NopContext, inbytes: ptr byte,
+              outbytes: ptr byte) {.inline.} =
+  outbytes = inbytes
+
+proc decrypt*(ctx: var NopContext, inbytes: ptr byte,
+              outbytes: ptr byte) {.inline.} =
+  outbytes = inbytes