diff --git a/waku/v2/node/jsonrpc/hexstrings.nim b/waku/v2/node/jsonrpc/hexstrings.nim
new file mode 100644
index 000000000..b595f9a82
--- /dev/null
+++ b/waku/v2/node/jsonrpc/hexstrings.nim
@@ -0,0 +1,204 @@
+# Nimbus
+# Copyright (c) 2018 Status Research & Development GmbH
+# Licensed under either of
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+# at your option.
+# This file may not be copied, modified, or distributed except according to
+# those terms.
+
+## This module implements the Ethereum hexadecimal string formats for JSON
+## See: https://github.com/ethereum/wiki/wiki/JSON-RPC#hex-value-encoding
+
+#[
+  Note:
+  The following types are converted to hex strings when marshalled to JSON:
+    * Hash256
+    * UInt256
+    * seq[byte]
+    * openArray[seq]
+    * PublicKey
+    * PrivateKey
+    * SymKey
+    * Bytes
+]#
+
+import
+  stint, stew/byteutils, eth/keys, eth/common/eth_types,
+  ../../../whisper/whisper_types
+
+type
+  HexDataStr* = distinct string
+  Identifier* = distinct string        # 32 bytes, no 0x prefix!
+  HexStrings = HexDataStr | Identifier
+
+# Hex validation
+
+template hasHexHeader(value: string): bool =
+  if value.len >= 2 and value[0] == '0' and value[1] in {'x', 'X'}: true
+  else: false
+
+template isHexChar(c: char): bool =
+  if  c notin {'0'..'9'} and
+      c notin {'a'..'f'} and
+      c notin {'A'..'F'}: false
+  else: true
+
+func isValidHexQuantity*(value: string): bool =
+  if not value.hasHexHeader:
+    return false
+  # No leading zeros (but allow 0x0)
+  if value.len < 3 or (value.len > 3 and value[2] == '0'): return false
+  for i in 2 ..< value.len:
+    let c = value[i]
+    if not c.isHexChar:
+      return false
+  return true
+
+func isValidHexData*(value: string, header = true): bool =
+  if header and not value.hasHexHeader:
+    return false
+  # Must be even number of digits
+  if value.len mod 2 != 0: return false
+  # Leading zeros are allowed
+  for i in 2 ..< value.len:
+    let c = value[i]
+    if not c.isHexChar:
+      return false
+  return true
+
+template isValidHexData(value: string, hexLen: int, header = true): bool =
+  value.len == hexLen and value.isValidHexData(header)
+
+func isValidIdentifier*(value: string): bool =
+  # 32 bytes for Whisper ID, no 0x prefix
+  result = value.isValidHexData(64, false)
+
+func isValidPublicKey*(value: string): bool =
+  # 65 bytes for Public Key plus 1 byte for 0x prefix
+  result = value.isValidHexData(132)
+
+func isValidPrivateKey*(value: string): bool =
+  # 32 bytes for Private Key plus 1 byte for 0x prefix
+  result = value.isValidHexData(66)
+
+func isValidSymKey*(value: string): bool =
+  # 32 bytes for Private Key plus 1 byte for 0x prefix
+  result = value.isValidHexData(66)
+
+func isValidHash256*(value: string): bool =
+  # 32 bytes for Hash256 plus 1 byte for 0x prefix
+  result = value.isValidHexData(66)
+
+const
+  SInvalidData = "Invalid hex data format for Ethereum"
+
+proc validateHexData*(value: string) {.inline.} =
+  if unlikely(not value.isValidHexData):
+    raise newException(ValueError, SInvalidData & ": " & value)
+
+# Initialisation
+
+proc hexDataStr*(value: string): HexDataStr {.inline.} =
+  value.validateHexData
+  result = value.HexDataStr
+
+# Converters for use in RPC
+
+import json
+from json_rpc/rpcserver import expect
+
+proc `%`*(value: HexStrings): JsonNode =
+  result = %(value.string)
+
+# Overloads to support expected representation of hex data
+
+proc `%`*(value: Hash256): JsonNode =
+  #result = %("0x" & $value) # More clean but no lowercase :(
+  result = %("0x" & value.data.toHex)
+
+proc `%`*(value: UInt256): JsonNode =
+  result = %("0x" & value.toString(16))
+
+proc `%`*(value: PublicKey): JsonNode =
+  result = %("0x04" & $value)
+
+proc `%`*(value: PrivateKey): JsonNode =
+  result = %("0x" & $value)
+
+proc `%`*(value: SymKey): JsonNode =
+  result = %("0x" & value.toHex)
+
+proc `%`*(value: seq[byte]): JsonNode =
+  if value.len > 0:
+    result = %("0x" & value.toHex)
+  else:
+    result = newJArray()
+
+# Helpers for the fromJson procs
+
+proc toPublicKey*(key: string): PublicKey {.inline.} =
+  result = PublicKey.fromHex(key[4 .. ^1]).tryGet()
+
+proc toPrivateKey*(key: string): PrivateKey {.inline.} =
+  result = PrivateKey.fromHex(key[2 .. ^1]).tryGet()
+
+proc toSymKey*(key: string): SymKey {.inline.} =
+  hexToByteArray(key[2 .. ^1], result)
+
+# Marshalling from JSON to Nim types that includes format checking
+
+func invalidMsg(name: string): string = "When marshalling from JSON, parameter \"" & name & "\" is not valid"
+
+proc fromJson*(n: JsonNode, argName: string, result: var HexDataStr) =
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.isValidHexData:
+    raise newException(ValueError, invalidMsg(argName) & " as Ethereum data \"" & hexStr & "\"")
+  result = hexStr.hexDataStr
+
+proc fromJson*(n: JsonNode, argName: string, result: var Identifier) =
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.isValidIdentifier:
+    raise newException(ValueError, invalidMsg(argName) & " as a identifier \"" & hexStr & "\"")
+  result = hexStr.Identifier
+
+proc fromJson*(n: JsonNode, argName: string, result: var UInt256) =
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not (hexStr.len <= 66 and hexStr.isValidHexQuantity):
+    raise newException(ValueError, invalidMsg(argName) & " as a UInt256 \"" & hexStr & "\"")
+  result = readUintBE[256](hexToPaddedByteArray[32](hexStr))
+
+proc fromJson*(n: JsonNode, argName: string, result: var PublicKey) =
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.isValidPublicKey:
+    raise newException(ValueError, invalidMsg(argName) & " as a public key \"" & hexStr & "\"")
+  result = hexStr.toPublicKey
+
+proc fromJson*(n: JsonNode, argName: string, result: var PrivateKey) =
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.isValidPrivateKey:
+    raise newException(ValueError, invalidMsg(argName) & " as a private key \"" & hexStr & "\"")
+  result = hexStr.toPrivateKey
+
+proc fromJson*(n: JsonNode, argName: string, result: var SymKey) =
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.isValidSymKey:
+    raise newException(ValueError, invalidMsg(argName) & " as a symmetric key \"" & hexStr & "\"")
+  result = toSymKey(hexStr)
+
+# Following procs currently required only for testing, the `createRpcSigs` macro
+# requires it as it will convert the JSON results back to the original Nim
+# types, but it needs the `fromJson` calls for those specific Nim types to do so
+
+proc fromJson*(n: JsonNode, argName: string, result: var Hash256) =
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.isValidHash256:
+    raise newException(ValueError, invalidMsg(argName) & " as a Hash256 \"" & hexStr & "\"")
+  hexToByteArray(hexStr, result.data)
diff --git a/waku/v2/node/jsonrpc/jsonrpc_utils.nim b/waku/v2/node/jsonrpc/jsonrpc_utils.nim
index 326a48e0e..225dca906 100644
--- a/waku/v2/node/jsonrpc/jsonrpc_utils.nim
+++ b/waku/v2/node/jsonrpc/jsonrpc_utils.nim
@@ -6,12 +6,12 @@ else:
 import
   std/[options, json],
   eth/keys,
-  ../../../v1/node/rpc/hexstrings,
   ../../protocol/waku_message,
   ../../protocol/waku_store,
   ../../protocol/waku_store/rpc,
   ../../utils/time,
   ../waku_payload,
+  ./hexstrings,
   ./jsonrpc_types
 
 export hexstrings