From 055599db3d1dc205fd61fd2f82c067a09ee8ca26 Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Wed, 27 Sep 2023 10:58:21 -0400
Subject: [PATCH 01/10] nibbles impl

---
 crypto/statetrie/nibbles/nibbles.go      | 170 +++++++++++++++++++
 crypto/statetrie/nibbles/nibbles_test.go | 200 +++++++++++++++++++++++
 2 files changed, 370 insertions(+)
 create mode 100644 crypto/statetrie/nibbles/nibbles.go
 create mode 100644 crypto/statetrie/nibbles/nibbles_test.go

diff --git a/crypto/statetrie/nibbles/nibbles.go b/crypto/statetrie/nibbles/nibbles.go
new file mode 100644
index 0000000000..90a385fd30
--- /dev/null
+++ b/crypto/statetrie/nibbles/nibbles.go
@@ -0,0 +1,170 @@
+// Copyright (C) 2019-2023 Algorand, Inc.
+// This file is part of go-algorand
+//
+// go-algorand is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// go-algorand is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with go-algorand.  If not, see <https://www.gnu.org/licenses/>.
+
+package nibbles
+
+import (
+	"bytes"
+	"errors"
+)
+
+// Nibbles are 4-bit values stored in an 8-bit byte arrays
+type Nibbles []byte
+
+const (
+	// evenIndicator for serialization when the last nibble in a byte array
+	// is part of the nibble array.
+	evenIndicator = 0x01
+	// oddIndicator for when it is not.
+	oddIndicator = 0x03
+)
+
+// MakeNibbles returns a nibble array from the byte array.  If oddLength is true,
+// the last 4 bits of the last byte of the array are ignored.
+func MakeNibbles(data []byte, oddLength bool) Nibbles {
+	return Unpack(data, oddLength)
+}
+
+// Unpack the byte array into a nibble array.  If oddLength is true, the last 4
+// bits of the last byte of the array are ignored.  Allocates a new byte
+// slice.
+//
+// [0x12, 0x30], true -> [0x1, 0x2, 0x3]
+// [0x12, 0x34], false -> [0x1, 0x2, 0x3, 0x4]
+// [0x12, 0x34], true -> [0x1, 0x2, 0x3]  <-- last byte last 4 bits ignored
+// [], false -> []
+// never to be called with [], true
+func Unpack(data []byte, oddLength bool) Nibbles {
+	length := len(data) * 2
+	if oddLength {
+		length = length - 1
+	}
+	ns := make([]byte, length)
+
+	j := 0
+	for i := 0; i < length; i++ {
+		if i%2 == 0 {
+			ns[i] = data[j] >> 4
+		} else {
+			ns[i] = data[j] & 0x0f
+			j++
+		}
+	}
+	return ns
+}
+
+// Pack the nibble array into a byte array.
+// Return the byte array and a bool indicating if the last byte is a full byte or
+// only the high 4 bits are part of the encoding
+// the last four bits of a oddLength byte encoding will always be zero.
+// Allocates a new byte slice.
+//
+// [0x1, 0x2, 0x3] -> [0x12, 0x30], true
+// [0x1, 0x2, 0x3, 0x4] -> [0x12, 0x34], false
+// [0x1] -> [0x10], true
+// [] -> [], false
+func Pack(nyb Nibbles) ([]byte, bool) {
+	length := len(nyb)
+	data := make([]byte, length/2+length%2)
+	for i := 0; i < length; i++ {
+		if i%2 == 0 {
+			data[i/2] = nyb[i] << 4
+		} else {
+			data[i/2] = data[i/2] | nyb[i]
+		}
+	}
+
+	return data, length%2 != 0
+}
+
+// Equal returns true if the two nibble arrays are equal
+// [0x1, 0x2, 0x3], [0x1, 0x2, 0x3] -> true
+// [0x1, 0x2, 0x3], [0x1, 0x2, 0x4] -> false
+// [0x1, 0x2, 0x3], [0x1] -> false
+// [0x1, 0x2, 0x3], [0x1, 0x2, 0x3, 0x4] -> false
+// [], [] -> true
+// [], [0x1] -> false
+func Equal(nyb1 Nibbles, nyb2 Nibbles) bool {
+	return bytes.Equal(nyb1, nyb2)
+}
+
+// ShiftLeft returns a slice of nyb1 that contains the Nibbles after the first
+// numNibbles
+func ShiftLeft(nyb1 Nibbles, numNibbles int) Nibbles {
+	if numNibbles <= 0 {
+		return nyb1
+	}
+	if numNibbles > len(nyb1) {
+		return nyb1[:0]
+	}
+
+	return nyb1[numNibbles:]
+}
+
+// SharedPrefix returns a slice from nyb1 that contains the shared prefix
+// between nyb1 and nyb2
+func SharedPrefix(nyb1 Nibbles, nyb2 Nibbles) Nibbles {
+	minLength := len(nyb1)
+	if len(nyb2) < minLength {
+		minLength = len(nyb2)
+	}
+	for i := 0; i < minLength; i++ {
+		if nyb1[i] != nyb2[i] {
+			return nyb1[:i]
+		}
+	}
+	return nyb1[:minLength]
+}
+
+// Serialize returns a byte array that represents the Nibbles
+// an empty nibble array is serialized as a single byte with value 0x3
+// as the empty nibble is considered to be full width
+//
+// [0x1, 0x2, 0x3] -> [0x12, 0x30, 0x01]
+// [0x1, 0x2, 0x3, 0x4] -> [0x12, 0x34, 0x03]
+// [] -> [0x03]
+func Serialize(nyb Nibbles) (data []byte) {
+	p, h := Pack(nyb)
+	length := len(p)
+	output := make([]byte, length+1)
+	copy(output, p)
+	if h {
+		// 0x1 is the arbitrary odd length indicator
+		output[length] = evenIndicator
+	} else {
+		// 0x3 is the arbitrary even length indicator
+		output[length] = oddIndicator
+	}
+
+	return output
+}
+
+// Deserialize returns a nibble array from the byte array.
+func Deserialize(encoding []byte) (Nibbles, error) {
+	var ns Nibbles
+	length := len(encoding)
+	if length == 0 {
+		return nil, errors.New("invalid encoding")
+	}
+	if encoding[length-1] == evenIndicator {
+		ns = Unpack(encoding[:length-1], true)
+	} else if encoding[length-1] == oddIndicator {
+		ns = Unpack(encoding[:length-1], false)
+	} else {
+		return nil, errors.New("invalid encoding")
+	}
+	return ns, nil
+}
diff --git a/crypto/statetrie/nibbles/nibbles_test.go b/crypto/statetrie/nibbles/nibbles_test.go
new file mode 100644
index 0000000000..c3833d1da1
--- /dev/null
+++ b/crypto/statetrie/nibbles/nibbles_test.go
@@ -0,0 +1,200 @@
+// Copyright (C) 2019-2023 Algorand, Inc.
+// This file is part of go-algorand
+//
+// go-algorand is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// go-algorand is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with go-algorand.  If not, see <https://www.gnu.org/licenses/>.
+
+package nibbles
+
+import (
+	"bytes"
+	"github.com/algorand/go-algorand/test/partitiontest"
+	"github.com/stretchr/testify/require"
+	"math/rand"
+	"testing"
+	"time"
+)
+
+func TestNibblesRandom(t *testing.T) {
+	partitiontest.PartitionTest(t)
+	t.Parallel()
+
+	seed := time.Now().UnixNano()
+	localRand := rand.New(rand.NewSource(seed))
+	defer func() {
+		if t.Failed() {
+			t.Logf("The seed was %d", seed)
+		}
+	}()
+
+	for i := 0; i < 1_000; i++ {
+		length := localRand.Intn(8192) + 1
+		data := make([]byte, length)
+		localRand.Read(data)
+		half := localRand.Intn(2) == 0 // half of the time, we have an odd number of nibbles
+		if half && localRand.Intn(2) == 0 {
+			data[len(data)-1] &= 0xf0 // sometimes clear the last nibble, sometimes do not
+		}
+		nibbles := MakeNibbles(data, half)
+
+		data2 := Serialize(nibbles)
+		nibbles2, err := Deserialize(data2)
+		require.NoError(t, err)
+		require.Equal(t, nibbles, nibbles2)
+
+		if half {
+			data[len(data)-1] &= 0xf0 // clear last nibble
+		}
+		packed, odd := Pack(nibbles)
+		require.Equal(t, odd, half)
+		require.Equal(t, packed, data)
+		unpacked := Unpack(packed, odd)
+		require.Equal(t, nibbles, unpacked)
+
+		packed, odd = Pack(nibbles2)
+		require.Equal(t, odd, half)
+		require.Equal(t, packed, data)
+		unpacked = Unpack(packed, odd)
+		require.Equal(t, nibbles2, unpacked)
+	}
+}
+
+func TestNibbles(t *testing.T) {
+	partitiontest.PartitionTest(t)
+	t.Parallel()
+
+	sampleNibbles := []Nibbles{
+		{0x0, 0x1, 0x2, 0x3, 0x4},
+		{0x4, 0x1, 0x2, 0x3, 0x4},
+		{0x0, 0x0, 0x2, 0x3, 0x5},
+		{0x0, 0x1, 0x2, 0x3, 0x4, 0x5},
+		{},
+		{0x1},
+	}
+
+	sampleNibblesPacked := [][]byte{
+		{0x01, 0x23, 0x40},
+		{0x41, 0x23, 0x40},
+		{0x00, 0x23, 0x50},
+		{0x01, 0x23, 0x45},
+		{},
+		{0x10},
+	}
+
+	sampleNibblesShifted1 := []Nibbles{
+		{0x1, 0x2, 0x3, 0x4},
+		{0x1, 0x2, 0x3, 0x4},
+		{0x0, 0x2, 0x3, 0x5},
+		{0x1, 0x2, 0x3, 0x4, 0x5},
+		{},
+		{},
+	}
+
+	sampleNibblesShifted2 := []Nibbles{
+		{0x2, 0x3, 0x4},
+		{0x2, 0x3, 0x4},
+		{0x2, 0x3, 0x5},
+		{0x2, 0x3, 0x4, 0x5},
+		{},
+		{},
+	}
+
+	for i, n := range sampleNibbles {
+		b, oddLength := Pack(n)
+		if oddLength {
+			// require that oddLength packs returns a byte slice with the last nibble set to 0x0
+			require.Equal(t, b[len(b)-1]&0x0f == 0x00, true)
+		}
+
+		require.Equal(t, oddLength == (len(n)%2 == 1), true)
+		require.Equal(t, bytes.Equal(b, sampleNibblesPacked[i]), true)
+
+		unp := Unpack(b, oddLength)
+		require.Equal(t, bytes.Equal(unp, n), true)
+
+	}
+	for i, n := range sampleNibbles {
+		require.Equal(t, bytes.Equal(ShiftLeft(n, -2), sampleNibbles[i]), true)
+		require.Equal(t, bytes.Equal(ShiftLeft(n, -1), sampleNibbles[i]), true)
+		require.Equal(t, bytes.Equal(ShiftLeft(n, 0), sampleNibbles[i]), true)
+		require.Equal(t, bytes.Equal(ShiftLeft(n, 1), sampleNibblesShifted1[i]), true)
+		require.Equal(t, bytes.Equal(ShiftLeft(n, 2), sampleNibblesShifted2[i]), true)
+	}
+
+	sampleSharedNibbles := [][]Nibbles{
+		{{0x0, 0x1, 0x2, 0x9, 0x2}, {0x0, 0x1, 0x2}},
+		{{0x4, 0x1}, {0x4, 0x1}},
+		{{0x9, 0x2, 0x3}, {}},
+		{{0x0}, {0x0}},
+		{{}, {}},
+	}
+	for i, n := range sampleSharedNibbles {
+		shared := SharedPrefix(n[0], sampleNibbles[i])
+		require.Equal(t, bytes.Equal(shared, n[1]), true)
+		shared = SharedPrefix(sampleNibbles[i], n[0])
+		require.Equal(t, bytes.Equal(shared, n[1]), true)
+	}
+
+	sampleSerialization := []Nibbles{
+		{0x0, 0x1, 0x2, 0x9, 0x2},
+		{0x4, 0x1},
+		{0x4, 0x1, 0x4, 0xf},
+		{0x4, 0x1, 0x4, 0xf, 0x0},
+		{0x9, 0x2, 0x3},
+		{},
+		{0x05},
+		{},
+	}
+
+	for _, n := range sampleSerialization {
+		nbytes := Serialize(n)
+		n2, err := Deserialize(nbytes)
+		require.NoError(t, err)
+		require.Equal(t, bytes.Equal(n, n2), true)
+	}
+
+	makeNibblesTestExpected := Nibbles{0x0, 0x1, 0x2, 0x9, 0x2}
+	makeNibblesTestData := []byte{0x01, 0x29, 0x20}
+	mntr := MakeNibbles(makeNibblesTestData, true)
+	require.Equal(t, bytes.Equal(mntr, makeNibblesTestExpected), true)
+	makeNibblesTestExpectedFW := Nibbles{0x0, 0x1, 0x2, 0x9, 0x2, 0x0}
+	mntr2 := MakeNibbles(makeNibblesTestData, false)
+	require.Equal(t, bytes.Equal(mntr2, makeNibblesTestExpectedFW), true)
+
+	sampleEqualFalse := [][]Nibbles{
+		{{0x0, 0x1, 0x2, 0x9, 0x2}, {0x0, 0x1, 0x2, 0x9}},
+		{{0x0, 0x1, 0x2, 0x9}, {0x0, 0x1, 0x2, 0x9, 0x2}},
+		{{0x0, 0x1, 0x2, 0x9, 0x2}, {}},
+		{{}, {0x0, 0x1, 0x2, 0x9, 0x2}},
+		{{0x0}, {}},
+		{{}, {0x0}},
+		{{}, {0x1}},
+	}
+	for _, n := range sampleEqualFalse {
+		ds := Serialize(n[0])
+		us, e := Deserialize(ds)
+		require.NoError(t, e)
+		require.Equal(t, Equal(n[0], us), true)
+		require.Equal(t, Equal(n[0], n[0]), true)
+		require.Equal(t, Equal(us, n[0]), true)
+		require.Equal(t, Equal(n[0], n[1]), false)
+		require.Equal(t, Equal(us, n[1]), false)
+		require.Equal(t, Equal(n[1], n[0]), false)
+		require.Equal(t, Equal(n[1], us), false)
+	}
+
+	_, e := Deserialize([]byte{})
+	require.Error(t, e)
+	_, e = Deserialize([]byte{0x02})
+	require.Error(t, e)
+}

From d9f8546c831471680862e4bd08b9eae8bf542b5c Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Fri, 29 Sep 2023 13:03:13 +0100
Subject: [PATCH 02/10] cr

---
 crypto/statetrie/nibbles/nibbles_test.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/crypto/statetrie/nibbles/nibbles_test.go b/crypto/statetrie/nibbles/nibbles_test.go
index c3833d1da1..91cc59487f 100644
--- a/crypto/statetrie/nibbles/nibbles_test.go
+++ b/crypto/statetrie/nibbles/nibbles_test.go
@@ -17,12 +17,14 @@
 package nibbles
 
 import (
+	"time"
 	"bytes"
-	"github.com/algorand/go-algorand/test/partitiontest"
-	"github.com/stretchr/testify/require"
-	"math/rand"
 	"testing"
-	"time"
+	"math/rand"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/algorand/go-algorand/test/partitiontest"
 )
 
 func TestNibblesRandom(t *testing.T) {

From 87d9c411da57ed0cafd57821d18d1190887cd16b Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Sun, 8 Oct 2023 00:53:02 +0100
Subject: [PATCH 03/10] cr

---
 crypto/statetrie/nibbles/nibbles.go      | 41 +++++++++++-------------
 crypto/statetrie/nibbles/nibbles_test.go | 14 ++++++--
 2 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/crypto/statetrie/nibbles/nibbles.go b/crypto/statetrie/nibbles/nibbles.go
index 90a385fd30..3eafb6bd26 100644
--- a/crypto/statetrie/nibbles/nibbles.go
+++ b/crypto/statetrie/nibbles/nibbles.go
@@ -25,29 +25,23 @@ import (
 type Nibbles []byte
 
 const (
-	// evenIndicator for serialization when the last nibble in a byte array
-	// is part of the nibble array.
-	evenIndicator = 0x01
-	// oddIndicator for when it is not.
-	oddIndicator = 0x03
+	// oddIndicator for serialization when the last nibble in a byte array
+	// is not part of the nibble array.
+	oddIndicator = 0x01
+	// evenIndicator for when it is.
+	evenIndicator = 0x03
 )
 
 // MakeNibbles returns a nibble array from the byte array.  If oddLength is true,
-// the last 4 bits of the last byte of the array are ignored.
-func MakeNibbles(data []byte, oddLength bool) Nibbles {
-	return Unpack(data, oddLength)
-}
-
-// Unpack the byte array into a nibble array.  If oddLength is true, the last 4
-// bits of the last byte of the array are ignored.  Allocates a new byte
-// slice.
+// the last 4 bits of the last byte of the array are ignored.  
 //
 // [0x12, 0x30], true -> [0x1, 0x2, 0x3]
 // [0x12, 0x34], false -> [0x1, 0x2, 0x3, 0x4]
 // [0x12, 0x34], true -> [0x1, 0x2, 0x3]  <-- last byte last 4 bits ignored
 // [], false -> []
 // never to be called with [], true
-func Unpack(data []byte, oddLength bool) Nibbles {
+// Allocates a new byte slice.
+func MakeNibbles(data []byte, oddLength bool) Nibbles {
 	length := len(data) * 2
 	if oddLength {
 		length = length - 1
@@ -142,11 +136,11 @@ func Serialize(nyb Nibbles) (data []byte) {
 	output := make([]byte, length+1)
 	copy(output, p)
 	if h {
-		// 0x1 is the arbitrary odd length indicator
-		output[length] = evenIndicator
-	} else {
-		// 0x3 is the arbitrary even length indicator
+		// 0x01 is the odd length indicator
 		output[length] = oddIndicator
+	} else {
+		// 0x03 is the even length indicator
+		output[length] = evenIndicator
 	}
 
 	return output
@@ -159,10 +153,13 @@ func Deserialize(encoding []byte) (Nibbles, error) {
 	if length == 0 {
 		return nil, errors.New("invalid encoding")
 	}
-	if encoding[length-1] == evenIndicator {
-		ns = Unpack(encoding[:length-1], true)
-	} else if encoding[length-1] == oddIndicator {
-		ns = Unpack(encoding[:length-1], false)
+	if encoding[length-1] == oddIndicator {
+        if length == 1 {
+    		return nil, errors.New("invalid encoding")
+        }
+		ns = MakeNibbles(encoding[:length-1], true)
+	} else if encoding[length-1] == evenIndicator {
+		ns = MakeNibbles(encoding[:length-1], false)
 	} else {
 		return nil, errors.New("invalid encoding")
 	}
diff --git a/crypto/statetrie/nibbles/nibbles_test.go b/crypto/statetrie/nibbles/nibbles_test.go
index 91cc59487f..ef8ff32c1b 100644
--- a/crypto/statetrie/nibbles/nibbles_test.go
+++ b/crypto/statetrie/nibbles/nibbles_test.go
@@ -60,17 +60,25 @@ func TestNibblesRandom(t *testing.T) {
 		packed, odd := Pack(nibbles)
 		require.Equal(t, odd, half)
 		require.Equal(t, packed, data)
-		unpacked := Unpack(packed, odd)
+		unpacked := MakeNibbles(packed, odd)
 		require.Equal(t, nibbles, unpacked)
 
 		packed, odd = Pack(nibbles2)
 		require.Equal(t, odd, half)
 		require.Equal(t, packed, data)
-		unpacked = Unpack(packed, odd)
+		unpacked = MakeNibbles(packed, odd)
 		require.Equal(t, nibbles2, unpacked)
 	}
 }
 
+func TestNibblesDeserialize(t *testing.T) {
+	partitiontest.PartitionTest(t)
+	t.Parallel()
+    enc := []byte{0x01}
+    _, err := Deserialize(enc)
+    require.Error(t, err, "should return invalid encoding error")
+}
+
 func TestNibbles(t *testing.T) {
 	partitiontest.PartitionTest(t)
 	t.Parallel()
@@ -121,7 +129,7 @@ func TestNibbles(t *testing.T) {
 		require.Equal(t, oddLength == (len(n)%2 == 1), true)
 		require.Equal(t, bytes.Equal(b, sampleNibblesPacked[i]), true)
 
-		unp := Unpack(b, oddLength)
+		unp := MakeNibbles(b, oddLength)
 		require.Equal(t, bytes.Equal(unp, n), true)
 
 	}

From c89239b22e34faa8efdaacee2518009797077b26 Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Wed, 8 Nov 2023 22:32:11 -0500
Subject: [PATCH 04/10] fmt

---
 crypto/statetrie/nibbles/nibbles.go      |  8 ++++----
 crypto/statetrie/nibbles/nibbles_test.go | 10 +++++-----
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/crypto/statetrie/nibbles/nibbles.go b/crypto/statetrie/nibbles/nibbles.go
index 3eafb6bd26..10e175832a 100644
--- a/crypto/statetrie/nibbles/nibbles.go
+++ b/crypto/statetrie/nibbles/nibbles.go
@@ -33,7 +33,7 @@ const (
 )
 
 // MakeNibbles returns a nibble array from the byte array.  If oddLength is true,
-// the last 4 bits of the last byte of the array are ignored.  
+// the last 4 bits of the last byte of the array are ignored.
 //
 // [0x12, 0x30], true -> [0x1, 0x2, 0x3]
 // [0x12, 0x34], false -> [0x1, 0x2, 0x3, 0x4]
@@ -154,9 +154,9 @@ func Deserialize(encoding []byte) (Nibbles, error) {
 		return nil, errors.New("invalid encoding")
 	}
 	if encoding[length-1] == oddIndicator {
-        if length == 1 {
-    		return nil, errors.New("invalid encoding")
-        }
+		if length == 1 {
+			return nil, errors.New("invalid encoding")
+		}
 		ns = MakeNibbles(encoding[:length-1], true)
 	} else if encoding[length-1] == evenIndicator {
 		ns = MakeNibbles(encoding[:length-1], false)
diff --git a/crypto/statetrie/nibbles/nibbles_test.go b/crypto/statetrie/nibbles/nibbles_test.go
index ef8ff32c1b..6ab8092fbe 100644
--- a/crypto/statetrie/nibbles/nibbles_test.go
+++ b/crypto/statetrie/nibbles/nibbles_test.go
@@ -17,10 +17,10 @@
 package nibbles
 
 import (
-	"time"
 	"bytes"
-	"testing"
 	"math/rand"
+	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 
@@ -74,9 +74,9 @@ func TestNibblesRandom(t *testing.T) {
 func TestNibblesDeserialize(t *testing.T) {
 	partitiontest.PartitionTest(t)
 	t.Parallel()
-    enc := []byte{0x01}
-    _, err := Deserialize(enc)
-    require.Error(t, err, "should return invalid encoding error")
+	enc := []byte{0x01}
+	_, err := Deserialize(enc)
+	require.Error(t, err, "should return invalid encoding error")
 }
 
 func TestNibbles(t *testing.T) {

From 1a0fd5295f834600814ae811de660a598936ea68 Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Wed, 8 Nov 2023 22:42:15 -0500
Subject: [PATCH 05/10] serialize-deserialize capacity

---
 crypto/statetrie/nibbles/nibbles.go | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/crypto/statetrie/nibbles/nibbles.go b/crypto/statetrie/nibbles/nibbles.go
index 10e175832a..6dc5e53476 100644
--- a/crypto/statetrie/nibbles/nibbles.go
+++ b/crypto/statetrie/nibbles/nibbles.go
@@ -1,4 +1,4 @@
-// Copyright (C) 2019-2023 Algorand, Inc.
+// Copyright (C) 2018-2023 Algorand, Inc.
 // This file is part of go-algorand
 //
 // go-algorand is free software: you can redistribute it and/or modify
@@ -72,7 +72,7 @@ func MakeNibbles(data []byte, oddLength bool) Nibbles {
 // [] -> [], false
 func Pack(nyb Nibbles) ([]byte, bool) {
 	length := len(nyb)
-	data := make([]byte, length/2+length%2)
+	data := make([]byte, length/2+length%2, length/2+length%2+1)
 	for i := 0; i < length; i++ {
 		if i%2 == 0 {
 			data[i/2] = nyb[i] << 4
@@ -131,19 +131,13 @@ func SharedPrefix(nyb1 Nibbles, nyb2 Nibbles) Nibbles {
 // [0x1, 0x2, 0x3, 0x4] -> [0x12, 0x34, 0x03]
 // [] -> [0x03]
 func Serialize(nyb Nibbles) (data []byte) {
-	p, h := Pack(nyb)
-	length := len(p)
-	output := make([]byte, length+1)
-	copy(output, p)
-	if h {
+	if p, h := Pack(nyb); h {
 		// 0x01 is the odd length indicator
-		output[length] = oddIndicator
+		return append(p, oddIndicator)
 	} else {
 		// 0x03 is the even length indicator
-		output[length] = evenIndicator
+		return append(p, evenIndicator)
 	}
-
-	return output
 }
 
 // Deserialize returns a nibble array from the byte array.

From d3f1effe65181082b7a1f59065630c0b82a3f76e Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Wed, 8 Nov 2023 23:10:02 -0500
Subject: [PATCH 06/10] addl test

---
 crypto/statetrie/nibbles/nibbles_test.go | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/crypto/statetrie/nibbles/nibbles_test.go b/crypto/statetrie/nibbles/nibbles_test.go
index 6ab8092fbe..527862fbeb 100644
--- a/crypto/statetrie/nibbles/nibbles_test.go
+++ b/crypto/statetrie/nibbles/nibbles_test.go
@@ -18,6 +18,7 @@ package nibbles
 
 import (
 	"bytes"
+	"fmt"
 	"math/rand"
 	"testing"
 	"time"
@@ -170,7 +171,14 @@ func TestNibbles(t *testing.T) {
 		nbytes := Serialize(n)
 		n2, err := Deserialize(nbytes)
 		require.NoError(t, err)
-		require.Equal(t, bytes.Equal(n, n2), true)
+		require.True(t, bytes.Equal(n, n2))
+		require.Equal(t, len(nbytes), len(n)/2+len(n)%2+1, fmt.Sprintf("nbytes: %v, n: %v", nbytes, n))
+		if len(n)%2 == 0 {
+			require.Equal(t, nbytes[len(nbytes)-1], uint8(evenIndicator))
+		} else {
+			require.Equal(t, nbytes[len(nbytes)-1], uint8(oddIndicator))
+			require.Equal(t, nbytes[len(nbytes)-2]&0x0F, uint8(0))
+		}
 	}
 
 	makeNibblesTestExpected := Nibbles{0x0, 0x1, 0x2, 0x9, 0x2}

From 6e960edafbb1420846806684acbc7d28caa3cc51 Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Thu, 9 Nov 2023 10:43:51 -0500
Subject: [PATCH 07/10] reviewdog

---
 crypto/statetrie/nibbles/nibbles.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/crypto/statetrie/nibbles/nibbles.go b/crypto/statetrie/nibbles/nibbles.go
index 6dc5e53476..0419f31571 100644
--- a/crypto/statetrie/nibbles/nibbles.go
+++ b/crypto/statetrie/nibbles/nibbles.go
@@ -134,10 +134,9 @@ func Serialize(nyb Nibbles) (data []byte) {
 	if p, h := Pack(nyb); h {
 		// 0x01 is the odd length indicator
 		return append(p, oddIndicator)
-	} else {
-		// 0x03 is the even length indicator
-		return append(p, evenIndicator)
 	}
+	// 0x03 is the even length indicator
+	return append(p, evenIndicator)
 }
 
 // Deserialize returns a nibble array from the byte array.

From a6118ba94d88ad8de637318f59771d1922eb65c1 Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Thu, 9 Nov 2023 10:46:25 -0500
Subject: [PATCH 08/10] licence

---
 crypto/statetrie/nibbles/nibbles.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/statetrie/nibbles/nibbles.go b/crypto/statetrie/nibbles/nibbles.go
index 0419f31571..47b62d4129 100644
--- a/crypto/statetrie/nibbles/nibbles.go
+++ b/crypto/statetrie/nibbles/nibbles.go
@@ -1,4 +1,4 @@
-// Copyright (C) 2018-2023 Algorand, Inc.
+// Copyright (C) 2019-2023 Algorand, Inc.
 // This file is part of go-algorand
 //
 // go-algorand is free software: you can redistribute it and/or modify

From 6dc8758f5e3526f4d25e401f8c55e43890f06755 Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Thu, 9 Nov 2023 10:54:26 -0500
Subject: [PATCH 09/10] reviewdog

---
 crypto/statetrie/nibbles/nibbles.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/crypto/statetrie/nibbles/nibbles.go b/crypto/statetrie/nibbles/nibbles.go
index 47b62d4129..42c64b9269 100644
--- a/crypto/statetrie/nibbles/nibbles.go
+++ b/crypto/statetrie/nibbles/nibbles.go
@@ -131,7 +131,8 @@ func SharedPrefix(nyb1 Nibbles, nyb2 Nibbles) Nibbles {
 // [0x1, 0x2, 0x3, 0x4] -> [0x12, 0x34, 0x03]
 // [] -> [0x03]
 func Serialize(nyb Nibbles) (data []byte) {
-	if p, h := Pack(nyb); h {
+	p, h := Pack(nyb)
+	if h {
 		// 0x01 is the odd length indicator
 		return append(p, oddIndicator)
 	}

From 615552d68d33dbbbfbc14e9b3ccea367cf3cec94 Mon Sep 17 00:00:00 2001
From: Bob Broderick <bbroder@ujicapital.com>
Date: Thu, 9 Nov 2023 16:20:17 -0500
Subject: [PATCH 10/10] makeNibbles

---
 crypto/statetrie/nibbles/nibbles.go      | 60 ++++++++++++------------
 crypto/statetrie/nibbles/nibbles_test.go | 12 ++---
 2 files changed, 36 insertions(+), 36 deletions(-)

diff --git a/crypto/statetrie/nibbles/nibbles.go b/crypto/statetrie/nibbles/nibbles.go
index 42c64b9269..8a8409b6b0 100644
--- a/crypto/statetrie/nibbles/nibbles.go
+++ b/crypto/statetrie/nibbles/nibbles.go
@@ -32,34 +32,6 @@ const (
 	evenIndicator = 0x03
 )
 
-// MakeNibbles returns a nibble array from the byte array.  If oddLength is true,
-// the last 4 bits of the last byte of the array are ignored.
-//
-// [0x12, 0x30], true -> [0x1, 0x2, 0x3]
-// [0x12, 0x34], false -> [0x1, 0x2, 0x3, 0x4]
-// [0x12, 0x34], true -> [0x1, 0x2, 0x3]  <-- last byte last 4 bits ignored
-// [], false -> []
-// never to be called with [], true
-// Allocates a new byte slice.
-func MakeNibbles(data []byte, oddLength bool) Nibbles {
-	length := len(data) * 2
-	if oddLength {
-		length = length - 1
-	}
-	ns := make([]byte, length)
-
-	j := 0
-	for i := 0; i < length; i++ {
-		if i%2 == 0 {
-			ns[i] = data[j] >> 4
-		} else {
-			ns[i] = data[j] & 0x0f
-			j++
-		}
-	}
-	return ns
-}
-
 // Pack the nibble array into a byte array.
 // Return the byte array and a bool indicating if the last byte is a full byte or
 // only the high 4 bits are part of the encoding
@@ -151,11 +123,39 @@ func Deserialize(encoding []byte) (Nibbles, error) {
 		if length == 1 {
 			return nil, errors.New("invalid encoding")
 		}
-		ns = MakeNibbles(encoding[:length-1], true)
+		ns = makeNibbles(encoding[:length-1], true)
 	} else if encoding[length-1] == evenIndicator {
-		ns = MakeNibbles(encoding[:length-1], false)
+		ns = makeNibbles(encoding[:length-1], false)
 	} else {
 		return nil, errors.New("invalid encoding")
 	}
 	return ns, nil
 }
+
+// makeNibbles returns a nibble array from the byte array.  If oddLength is true,
+// the last 4 bits of the last byte of the array are ignored.
+//
+// [0x12, 0x30], true -> [0x1, 0x2, 0x3]
+// [0x12, 0x34], false -> [0x1, 0x2, 0x3, 0x4]
+// [0x12, 0x34], true -> [0x1, 0x2, 0x3]  <-- last byte last 4 bits ignored
+// [], false -> []
+// never to be called with [], true
+// Allocates a new byte slice.
+func makeNibbles(data []byte, oddLength bool) Nibbles {
+	length := len(data) * 2
+	if oddLength {
+		length = length - 1
+	}
+	ns := make([]byte, length)
+
+	j := 0
+	for i := 0; i < length; i++ {
+		if i%2 == 0 {
+			ns[i] = data[j] >> 4
+		} else {
+			ns[i] = data[j] & 0x0f
+			j++
+		}
+	}
+	return ns
+}
diff --git a/crypto/statetrie/nibbles/nibbles_test.go b/crypto/statetrie/nibbles/nibbles_test.go
index 527862fbeb..c088f1dd8a 100644
--- a/crypto/statetrie/nibbles/nibbles_test.go
+++ b/crypto/statetrie/nibbles/nibbles_test.go
@@ -48,7 +48,7 @@ func TestNibblesRandom(t *testing.T) {
 		if half && localRand.Intn(2) == 0 {
 			data[len(data)-1] &= 0xf0 // sometimes clear the last nibble, sometimes do not
 		}
-		nibbles := MakeNibbles(data, half)
+		nibbles := makeNibbles(data, half)
 
 		data2 := Serialize(nibbles)
 		nibbles2, err := Deserialize(data2)
@@ -61,13 +61,13 @@ func TestNibblesRandom(t *testing.T) {
 		packed, odd := Pack(nibbles)
 		require.Equal(t, odd, half)
 		require.Equal(t, packed, data)
-		unpacked := MakeNibbles(packed, odd)
+		unpacked := makeNibbles(packed, odd)
 		require.Equal(t, nibbles, unpacked)
 
 		packed, odd = Pack(nibbles2)
 		require.Equal(t, odd, half)
 		require.Equal(t, packed, data)
-		unpacked = MakeNibbles(packed, odd)
+		unpacked = makeNibbles(packed, odd)
 		require.Equal(t, nibbles2, unpacked)
 	}
 }
@@ -130,7 +130,7 @@ func TestNibbles(t *testing.T) {
 		require.Equal(t, oddLength == (len(n)%2 == 1), true)
 		require.Equal(t, bytes.Equal(b, sampleNibblesPacked[i]), true)
 
-		unp := MakeNibbles(b, oddLength)
+		unp := makeNibbles(b, oddLength)
 		require.Equal(t, bytes.Equal(unp, n), true)
 
 	}
@@ -183,10 +183,10 @@ func TestNibbles(t *testing.T) {
 
 	makeNibblesTestExpected := Nibbles{0x0, 0x1, 0x2, 0x9, 0x2}
 	makeNibblesTestData := []byte{0x01, 0x29, 0x20}
-	mntr := MakeNibbles(makeNibblesTestData, true)
+	mntr := makeNibbles(makeNibblesTestData, true)
 	require.Equal(t, bytes.Equal(mntr, makeNibblesTestExpected), true)
 	makeNibblesTestExpectedFW := Nibbles{0x0, 0x1, 0x2, 0x9, 0x2, 0x0}
-	mntr2 := MakeNibbles(makeNibblesTestData, false)
+	mntr2 := makeNibbles(makeNibblesTestData, false)
 	require.Equal(t, bytes.Equal(mntr2, makeNibblesTestExpectedFW), true)
 
 	sampleEqualFalse := [][]Nibbles{