diff --git a/stateless/multi_keys.nim b/stateless/multi_keys.nim
index 00c6e66c2..75607dc5f 100644
--- a/stateless/multi_keys.nim
+++ b/stateless/multi_keys.nim
@@ -1,36 +1,30 @@
-import eth/common, eth/trie/db, tables, algorithm, stew/byteutils
+import
+  eth/common, eth/trie/[db, nibbles], algorithm, stew/byteutils,
+  ./witness_types
 
 type
   KeyHash = array[32, byte]
 
-  Multikeys = object
-    hash: seq[KeyHash]
+  HashAddress = object
+    visited: bool
+    hash: KeyHash
+    address: EthAddress
 
-  Group = object
-    a, b: int
+  Multikeys* = object
+    keys: seq[HashAddress]
 
-proc toHash(x: string): KeyHash =
-  let len = min(x.len, 32)
-  for i in 0..<len:
-    result[i] = x[i].byte
+  Group* = object
+    a, b: int16
 
-proc `$`(x: KeyHash): string =
-  result = newString(x.len)
-  for i, c in x:
-    result[i] = c.char
+  BranchGroup* = object
+    mask*: uint
+    groups*: array[16, Group]
 
-let keys = [
-  "abcdefghijklmnopqrstuv",
-  "abcj34-09u3209u0jhfn93",
-  "couynnm3mm,op312u0jnnm",
-  "bad03he0823hhhf0hn1032",
-  "abcdefghon0384hr0h3240",
-  "baiju-94i-j2nh-9jdjlwk",
-  "bai2222-9ur34nonf08hn3"
-]
+  GroupNibble = object
+    nibble: byte
+    group: Group
 
-
-proc cmpHash(a, b: KeyHash): int =
+func cmpHash(a, b: KeyHash): int =
   var i = 0
   var m = min(a.len, b.len)
   while i < m:
@@ -39,52 +33,119 @@ proc cmpHash(a, b: KeyHash): int =
     inc(i)
   result = a.len - b.len
 
-proc nextGroup(m: Multikeys, c: int, g: Group): Group =
-  result.a = g.b + 1
-  var head = m.hash[result.a][c]
-  let last = m.hash.len - 1
-  for i in result.a..<m.hash.len:
-    if m.hash[i][c] != head:
-      result.b = i - 1
+func cmpHash(a, b: HashAddress): int =
+  cmpHash(a.hash, b.hash)
+
+proc initMultiKeys*(addrs: openArray[EthAddress]): Multikeys =
+  result.keys = newSeq[HashAddress](addrs.len)
+  for i, a in addrs:
+    result.keys[i] = HashAddress(hash: keccak(a).data, address: a)
+  result.keys.sort(cmpHash)
+
+func `$`(x: KeyHash): string =
+  toHex(x)
+
+func initGroup*(m: Multikeys): Group =
+  result = Group(a: 0'i16, b: (m.keys.len - 1).int16)
+
+func initChildGroup(a: Group): Group =
+  result = Group(a: a.a-1'i16, b: a.a-1'i16)
+
+func getNibble(x: openArray[byte], i: int): byte =
+  if(i and 0x01) == 0x01:
+    result = x[i shr 1] and 0x0F
+  else:
+    result = x[i shr 1] shr 4
+
+func nextGroup(m: Multikeys, depth: int, g: Group): GroupNibble =
+  result.group.a = g.b + 1
+  result.nibble = getNibble(m.keys[result.group.a].hash, depth)
+  let last = (m.keys.len - 1).int16
+  for i in result.group.a..<m.keys.len.int16:
+    if getNibble(m.keys[i].hash, depth) != result.nibble:
+      result.group.b = i - 1
       break
     elif i == last:
-      result.b = last
+      result.group.b = last
 
-proc lastGroup(a: Group, g: Group): bool =
-  g.b == a.b
+func lastGroup(a: Group, g: Group): bool =
+  a.b == g.b
+
+func compareNibbles(x: openArray[byte], start: int, n: NibblesSeq): bool =
+  var i = 0
+  while i < n.len:
+    if getNibble(x, start + i) != n[i]:
+      return false
+    inc i
+  result = true
+
+func groups*(m: Multikeys, parentGroup: Group, depth: int): BranchGroup =
+  # similar to a branch node, the product of this func
+  # is a 16 bits bitmask and an array of max 16 groups
+  # if the bit is set, the n-th elem of array have a group
+  # each group consist of at least one key
+  var gn = GroupNibble(group: parentGroup.initChildGroup())
+  while not parentGroup.lastGroup(gn.group):
+    gn = m.nextGroup(depth, gn.group)
+    setBranchMaskBit(result.mask, gn.nibble.int)
+    result.groups[gn.nibble.int] = gn.group
+
+iterator groups*(m: Multikeys, depth: int, n: NibblesSeq, parentGroup: Group): (bool, Group) =
+  # using common-prefix comparison, this iterator
+  # will produce groups, usually only one match group
+  # the rest will be not match
+  # in case of wrong path, there will be no match at all
+  var g = Group(a: parentGroup.a, b: parentGroup.a)
+  var match = compareNibbles(m.keys[g.a].hash, depth, n)
+  let last = parentGroup.b
+  var haveMatch = false
+  var matchG: Group
+  var matchB: bool
+  for i in parentGroup.a..parentGroup.b:
+    if compareNibbles(m.keys[i].hash, depth, n) == match:
+      inc g.b
+    else:
+      haveMatch = true
+      matchB = match
+      matchG = g
+      match = not match
+      g = Group(a: g.b, b: g.b)
+    if i == last:
+      haveMatch = true
+      g.b = last
+      matchG = g
+      matchB = match
+    if haveMatch:
+      haveMatch = false
+      yield (matchB, matchG)
+
+let keys = [
+  hexToByteArray[20]("abcdef0a0b0c0d0e0f1234567890aabbccddeeff"),
+  hexToByteArray[20]("abc0000000000000000000000000000000000000"),
+  hexToByteArray[20]("cde9769bbcbdef9880932852388bdceabcdeadea"),
+  hexToByteArray[20]("bad03eaeaea69072375281381267397182bcdbef"),
+  hexToByteArray[20]("abcdefbbbbbbdddeefffaaccee19826736134298"),
+  hexToByteArray[20]("ba88888888dddddbbbbfffeeeccaa78128301389"),
+  hexToByteArray[20]("ba9084097472374372327238bbbcdffecadfecf3")
+]
 
 proc main() =
-  var m: Multikeys
-  for x in keys:
-    m.hash.add toHash(x)
+  var m = initMultikeys(keys)
 
-  m.hash.sort(cmpHash)
+  for x in m.keys:
+    echo x.hash
 
-  for x in m.hash:
-    echo x
+  var parentGroup = m.initGroup()
+  var depth = 1
+  var bg = m.groups(parentGroup, depth)
 
-  var a = Group(a: 0, b: m.hash.len - 1)
-  var c = 0
-  var g = Group(a: a.a-1, b: a.a-1)
-  while not a.lastGroup(g):
-    g = m.nextGroup(c, g)
-    echo g
+  for i in 0..<16:
+    if branchMaskBitIsSet(bg.mask, i):
+      echo bg.groups[i]
+
+  var p = Group(a: 0, b: 2)
+  var n = hexToByteArray[2]("cdef")
+  for j in groups(m, 2, initNibbleRange(n), p):
+    debugEcho j
 
-  echo "---"
-  c = 2
-  var b = Group(a: 3, b: 5)
-  g = Group(a: b.a-1, b: b.a-1)
-  while not  b.lastGroup(g):
-     g = m.nextGroup(c, g)
-     echo g
-  
-  
-  echo "---"
-  c = 2
-  b = Group(a: 6, b: 6)
-  g = Group(a: b.a-1, b: b.a-1)
-  while not  b.lastGroup(g):
-     g = m.nextGroup(c, g)
-     echo g
-  
 main()