bech32: back port improvements from decred/dcrd@9b88dd0

This commit brings a host of improvements to the bech32 package. The
public interface of the package remains unchanged.

Summary of changes:
* Improved error handling using dedicated error types. Programmatically
  detect if the errors produced are the expected ones.
* Improve test coverage to test more corner cases. Added test vectors
  from Bitcoin Core.
* Add a benchmark for a full encode/decode cycle of a bech32 string.
* Add a new function DecodeNoLimit, for decoding large bech32 encoded
  strings. It does NOT validate against the BIP-173 maximum length
  allowed for bech32 strings.
* Automatically convert the HRP to lowercase in Encode function.
* Improve performance of encode/decode functions by using
  strings.Builder.
* Improve memory allocation in ConvertBits function.
* Updated documentation.

Credits: @matheusd

Closes #152 and #168.
This commit is contained in:
Anirudha Bose 2020-07-14 12:12:06 +05:30 committed by John C. Vernaleo
parent 4031bdc69d
commit f281d151bb
3 changed files with 586 additions and 161 deletions

View file

@ -1,54 +1,196 @@
// Copyright (c) 2017 The btcsuite developers
// Copyright (c) 2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package bech32
import (
"fmt"
"strings"
)
// charset is the set of characters used in the data section of bech32 strings.
// Note that this is ordered, such that for a given charset[i], i is the binary
// value of the character.
const charset = "qpzry9x8gf2tvdw0s3jn54khce6mua7l"
// gen encodes the generator polynomial for the bech32 BCH checksum.
var gen = []int{0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3}
// Decode decodes a bech32 encoded string, returning the human-readable
// part and the data part excluding the checksum.
func Decode(bech string) (string, []byte, error) {
// The maximum allowed length for a bech32 string is 90. It must also
// be at least 8 characters, since it needs a non-empty HRP, a
// separator, and a 6 character checksum.
if len(bech) < 8 || len(bech) > 90 {
return "", nil, fmt.Errorf("invalid bech32 string length %d",
len(bech))
// toBytes converts each character in the string 'chars' to the value of the
// index of the correspoding character in 'charset'.
func toBytes(chars string) ([]byte, error) {
decoded := make([]byte, 0, len(chars))
for i := 0; i < len(chars); i++ {
index := strings.IndexByte(charset, chars[i])
if index < 0 {
return nil, ErrNonCharsetChar(chars[i])
}
decoded = append(decoded, byte(index))
}
// Only ASCII characters between 33 and 126 are allowed.
for i := 0; i < len(bech); i++ {
if bech[i] < 33 || bech[i] > 126 {
return "", nil, fmt.Errorf("invalid character in "+
"string: '%c'", bech[i])
return decoded, nil
}
// bech32Polymod calculates the BCH checksum for a given hrp, values and
// checksum data. Checksum is optional, and if nil a 0 checksum is assumed.
//
// Values and checksum (if provided) MUST be encoded as 5 bits per element (base
// 32), otherwise the results are undefined.
//
// For more details on the polymod calculation, please refer to BIP 173.
func bech32Polymod(hrp string, values, checksum []byte) int {
chk := 1
// Account for the high bits of the HRP in the checksum.
for i := 0; i < len(hrp); i++ {
b := chk >> 25
hiBits := int(hrp[i]) >> 5
chk = (chk&0x1ffffff)<<5 ^ hiBits
for i := 0; i < 5; i++ {
if (b>>uint(i))&1 == 1 {
chk ^= gen[i]
}
}
}
// The characters must be either all lowercase or all uppercase.
lower := strings.ToLower(bech)
upper := strings.ToUpper(bech)
if bech != lower && bech != upper {
return "", nil, fmt.Errorf("string not all lowercase or all " +
"uppercase")
// Account for the separator (0) between high and low bits of the HRP.
// x^0 == x, so we eliminate the redundant xor used in the other rounds.
b := chk >> 25
chk = (chk & 0x1ffffff) << 5
for i := 0; i < 5; i++ {
if (b>>uint(i))&1 == 1 {
chk ^= gen[i]
}
}
// We'll work with the lowercase string from now on.
bech = lower
// Account for the low bits of the HRP.
for i := 0; i < len(hrp); i++ {
b := chk >> 25
loBits := int(hrp[i]) & 31
chk = (chk&0x1ffffff)<<5 ^ loBits
for i := 0; i < 5; i++ {
if (b>>uint(i))&1 == 1 {
chk ^= gen[i]
}
}
}
// Account for the values.
for _, v := range values {
b := chk >> 25
chk = (chk&0x1ffffff)<<5 ^ int(v)
for i := 0; i < 5; i++ {
if (b>>uint(i))&1 == 1 {
chk ^= gen[i]
}
}
}
if checksum == nil {
// A nil checksum is used during encoding, so assume all bytes are zero.
// x^0 == x, so we eliminate the redundant xor used in the other rounds.
for v := 0; v < 6; v++ {
b := chk >> 25
chk = (chk & 0x1ffffff) << 5
for i := 0; i < 5; i++ {
if (b>>uint(i))&1 == 1 {
chk ^= gen[i]
}
}
}
} else {
// Checksum is provided during decoding, so use it.
for _, v := range checksum {
b := chk >> 25
chk = (chk&0x1ffffff)<<5 ^ int(v)
for i := 0; i < 5; i++ {
if (b>>uint(i))&1 == 1 {
chk ^= gen[i]
}
}
}
}
return chk
}
// writeBech32Checksum calculates the checksum data expected for a string that
// will have the given hrp and payload data and writes it to the provided string
// builder.
//
// The payload data MUST be encoded as a base 32 (5 bits per element) byte slice
// and the hrp MUST only use the allowed character set (ascii chars between 33
// and 126), otherwise the results are undefined.
//
// For more details on the checksum calculation, please refer to BIP 173.
func writeBech32Checksum(hrp string, data []byte, bldr *strings.Builder) {
polymod := bech32Polymod(hrp, data, nil) ^ 1
for i := 0; i < 6; i++ {
b := byte((polymod >> uint(5*(5-i))) & 31)
// This can't fail, given we explicitly cap the previous b byte by the
// first 31 bits.
c := charset[b]
bldr.WriteByte(c)
}
}
// bech32VerifyChecksum verifies whether the bech32 string specified by the
// provided hrp and payload data (encoded as 5 bits per element byte slice) has
// the correct checksum suffix.
//
// Data MUST have more than 6 elements, otherwise this function panics.
//
// For more details on the checksum verification, please refer to BIP 173.
func bech32VerifyChecksum(hrp string, data []byte) bool {
checksum := data[len(data)-6:]
values := data[:len(data)-6]
polymod := bech32Polymod(hrp, values, checksum)
return polymod == 1
}
// DecodeNoLimit decodes a bech32 encoded string, returning the human-readable
// part and the data part excluding the checksum. This function does NOT
// validate against the BIP-173 maximum length allowed for bech32 strings and
// is meant for use in custom applications (such as lightning network payment
// requests), NOT on-chain addresses.
//
// Note that the returned data is 5-bit (base32) encoded.
func DecodeNoLimit(bech string) (string, []byte, error) {
// The minimum allowed size of a bech32 string is 8 characters, since it
// needs a non-empty HRP, a separator, and a 6 character checksum.
if len(bech) < 8 {
return "", nil, ErrInvalidLength(len(bech))
}
// Only ASCII characters between 33 and 126 are allowed.
var hasLower, hasUpper bool
for i := 0; i < len(bech); i++ {
if bech[i] < 33 || bech[i] > 126 {
return "", nil, ErrInvalidCharacter(bech[i])
}
// The characters must be either all lowercase or all uppercase. Testing
// directly with ascii codes is safe here, given the previous test.
hasLower = hasLower || (bech[i] >= 97 && bech[i] <= 122)
hasUpper = hasUpper || (bech[i] >= 65 && bech[i] <= 90)
if hasLower && hasUpper {
return "", nil, ErrMixedCase{}
}
}
// Bech32 standard uses only the lowercase for of strings for checksum
// calculation.
if hasUpper {
bech = strings.ToLower(bech)
}
// The string is invalid if the last '1' is non-existent, it is the
// first character of the string (no human-readable part) or one of the
// last 6 characters of the string (since checksum cannot contain '1'),
// or if the string is more than 90 characters in total.
// last 6 characters of the string (since checksum cannot contain '1').
one := strings.LastIndexByte(bech, '1')
if one < 1 || one+7 > len(bech) {
return "", nil, fmt.Errorf("invalid index of 1")
return "", nil, ErrInvalidSeparatorIndex(one)
}
// The human-readable part is everything before the last '1'.
@ -59,85 +201,94 @@ func Decode(bech string) (string, []byte, error) {
// 'charset'.
decoded, err := toBytes(data)
if err != nil {
return "", nil, fmt.Errorf("failed converting data to bytes: "+
"%v", err)
return "", nil, err
}
// Verify if the checksum (stored inside decoded[:]) is valid, given the
// previously decoded hrp.
if !bech32VerifyChecksum(hrp, decoded) {
moreInfo := ""
checksum := bech[len(bech)-6:]
expected, err := toChars(bech32Checksum(hrp,
decoded[:len(decoded)-6]))
if err == nil {
moreInfo = fmt.Sprintf("Expected %v, got %v.",
expected, checksum)
// Invalid checksum. Calculate what it should have been, so that the
// error contains this information.
// Extract the payload bytes and actual checksum in the string.
actual := bech[len(bech)-6:]
payload := decoded[:len(decoded)-6]
// Calculate the expected checksum, given the hrp and payload data.
var expectedBldr strings.Builder
expectedBldr.Grow(6)
writeBech32Checksum(hrp, payload, &expectedBldr)
expected := expectedBldr.String()
err = ErrInvalidChecksum{
Expected: expected,
Actual: actual,
}
return "", nil, fmt.Errorf("checksum failed. " + moreInfo)
return "", nil, err
}
// We exclude the last 6 bytes, which is the checksum.
return hrp, decoded[:len(decoded)-6], nil
}
// Decode decodes a bech32 encoded string, returning the human-readable part and
// the data part excluding the checksum.
//
// Note that the returned data is 5-bit (base32) encoded.
func Decode(bech string) (string, []byte, error) {
// The maximum allowed length for a bech32 string is 90.
if len(bech) > 90 {
return "", nil, ErrInvalidLength(len(bech))
}
return DecodeNoLimit(bech)
}
// Encode encodes a byte slice into a bech32 string with the
// human-readable part hrb. Note that the bytes must each encode 5 bits
// (base32).
func Encode(hrp string, data []byte) (string, error) {
// Calculate the checksum of the data and append it at the end.
checksum := bech32Checksum(hrp, data)
combined := append(data, checksum...)
// The resulting bech32 string is the concatenation of the hrp, the
// separator 1, data and checksum. Everything after the separator is
// represented using the specified charset.
dataChars, err := toChars(combined)
if err != nil {
return "", fmt.Errorf("unable to convert data bytes to chars: "+
"%v", err)
}
return hrp + "1" + dataChars, nil
}
// separator 1, data and the 6-byte checksum.
var bldr strings.Builder
bldr.Grow(len(hrp) + 1 + len(data) + 6)
bldr.WriteString(hrp)
bldr.WriteString("1")
// toBytes converts each character in the string 'chars' to the value of the
// index of the correspoding character in 'charset'.
func toBytes(chars string) ([]byte, error) {
decoded := make([]byte, 0, len(chars))
for i := 0; i < len(chars); i++ {
index := strings.IndexByte(charset, chars[i])
if index < 0 {
return nil, fmt.Errorf("invalid character not part of "+
"charset: %v", chars[i])
}
decoded = append(decoded, byte(index))
}
return decoded, nil
}
// toChars converts the byte slice 'data' to a string where each byte in 'data'
// encodes the index of a character in 'charset'.
func toChars(data []byte) (string, error) {
result := make([]byte, 0, len(data))
// Write the data part, using the bech32 charset.
for _, b := range data {
if int(b) >= len(charset) {
return "", fmt.Errorf("invalid data byte: %v", b)
return "", ErrInvalidDataByte(b)
}
result = append(result, charset[b])
bldr.WriteByte(charset[b])
}
return string(result), nil
// Calculate and write the checksum of the data.
writeBech32Checksum(hrp, data, &bldr)
return bldr.String(), nil
}
// ConvertBits converts a byte slice where each byte is encoding fromBits bits,
// to a byte slice where each byte is encoding toBits bits.
func ConvertBits(data []byte, fromBits, toBits uint8, pad bool) ([]byte, error) {
if fromBits < 1 || fromBits > 8 || toBits < 1 || toBits > 8 {
return nil, fmt.Errorf("only bit groups between 1 and 8 allowed")
return nil, ErrInvalidBitGroups{}
}
// Determine the maximum size the resulting array can have after base
// conversion, so that we can size it a single time. This might be off
// by a byte depending on whether padding is used or not and if the input
// data is a multiple of both fromBits and toBits, but we ignore that and
// just size it to the maximum possible.
maxSize := len(data)*int(fromBits)/int(toBits) + 1
// The final bytes, each byte encoding toBits bits.
var regrouped []byte
regrouped := make([]byte, 0, maxSize)
// Keep track of the next byte we create and how many bits we have
// added to it out of the toBits goal.
// added to it out of the toBits goal.
nextByte := byte(0)
filledBits := uint8(0)
@ -170,7 +321,7 @@ func ConvertBits(data []byte, fromBits, toBits uint8, pad bool) ([]byte, error)
filledBits += toExtract
// If the nextByte is completely filled, we add it to
// our regrouped bytes and start on the next byte.
// our regrouped bytes and start on the next byte.
if filledBits == toBits {
regrouped = append(regrouped, nextByte)
filledBits = 0
@ -189,64 +340,8 @@ func ConvertBits(data []byte, fromBits, toBits uint8, pad bool) ([]byte, error)
// Any incomplete group must be <= 4 bits, and all zeroes.
if filledBits > 0 && (filledBits > 4 || nextByte != 0) {
return nil, fmt.Errorf("invalid incomplete group")
return nil, ErrInvalidIncompleteGroup{}
}
return regrouped, nil
}
// For more details on the checksum calculation, please refer to BIP 173.
func bech32Checksum(hrp string, data []byte) []byte {
// Convert the bytes to list of integers, as this is needed for the
// checksum calculation.
integers := make([]int, len(data))
for i, b := range data {
integers[i] = int(b)
}
values := append(bech32HrpExpand(hrp), integers...)
values = append(values, []int{0, 0, 0, 0, 0, 0}...)
polymod := bech32Polymod(values) ^ 1
var res []byte
for i := 0; i < 6; i++ {
res = append(res, byte((polymod>>uint(5*(5-i)))&31))
}
return res
}
// For more details on the polymod calculation, please refer to BIP 173.
func bech32Polymod(values []int) int {
chk := 1
for _, v := range values {
b := chk >> 25
chk = (chk&0x1ffffff)<<5 ^ v
for i := 0; i < 5; i++ {
if (b>>uint(i))&1 == 1 {
chk ^= gen[i]
}
}
}
return chk
}
// For more details on HRP expansion, please refer to BIP 173.
func bech32HrpExpand(hrp string) []int {
v := make([]int, 0, len(hrp)*2+1)
for i := 0; i < len(hrp); i++ {
v = append(v, int(hrp[i]>>5))
}
v = append(v, 0)
for i := 0; i < len(hrp); i++ {
v = append(v, int(hrp[i]&31))
}
return v
}
// For more details on the checksum verification, please refer to BIP 173.
func bech32VerifyChecksum(hrp string, data []byte) bool {
integers := make([]int, len(data))
for i, b := range data {
integers[i] = int(b)
}
concat := append(bech32HrpExpand(hrp), integers...)
return bech32Polymod(concat) == 1
}

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@ -1,54 +1,72 @@
// Copyright (c) 2017 The btcsuite developers
// Copyright (c) 2017-2020 The btcsuite developers
// Copyright (c) 2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package bech32_test
package bech32
import (
"bytes"
"encoding/hex"
"fmt"
"strings"
"testing"
"github.com/btcsuite/btcutil/bech32"
)
// TestBech32 tests whether decoding and re-encoding the valid BIP-173 test
// vectors works and if decoding invalid test vectors fails for the correct
// reason.
func TestBech32(t *testing.T) {
tests := []struct {
str string
valid bool
str string
expectedError error
}{
{"A12UEL5L", true},
{"an83characterlonghumanreadablepartthatcontainsthenumber1andtheexcludedcharactersbio1tt5tgs", true},
{"abcdef1qpzry9x8gf2tvdw0s3jn54khce6mua7lmqqqxw", true},
{"11qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqc8247j", true},
{"split1checkupstagehandshakeupstreamerranterredcaperred2y9e3w", true},
{"split1checkupstagehandshakeupstreamerranterredcaperred2y9e2w", false}, // invalid checksum
{"s lit1checkupstagehandshakeupstreamerranterredcaperredp8hs2p", false}, // invalid character (space) in hrp
{"spl\x7Ft1checkupstagehandshakeupstreamerranterredcaperred2y9e3w", false}, // invalid character (DEL) in hrp
{"split1cheo2y9e2w", false}, // invalid character (o) in data part
{"split1a2y9w", false}, // too short data part
{"1checkupstagehandshakeupstreamerranterredcaperred2y9e3w", false}, // empty hrp
{"11qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqsqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqc8247j", false}, // too long
{"A12UEL5L", nil},
{"an83characterlonghumanreadablepartthatcontainsthenumber1andtheexcludedcharactersbio1tt5tgs", nil},
{"abcdef1qpzry9x8gf2tvdw0s3jn54khce6mua7lmqqqxw", nil},
{"11qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqc8247j", nil},
{"split1checkupstagehandshakeupstreamerranterredcaperred2y9e3w", nil},
{"split1checkupstagehandshakeupstreamerranterredcaperred2y9e2w", ErrInvalidChecksum{"2y9e3w", "2y9e2w"}}, // invalid checksum
{"s lit1checkupstagehandshakeupstreamerranterredcaperredp8hs2p", ErrInvalidCharacter(' ')}, // invalid character (space) in hrp
{"spl\x7Ft1checkupstagehandshakeupstreamerranterredcaperred2y9e3w", ErrInvalidCharacter(127)}, // invalid character (DEL) in hrp
{"split1cheo2y9e2w", ErrNonCharsetChar('o')}, // invalid character (o) in data part
{"split1a2y9w", ErrInvalidSeparatorIndex(5)}, // too short data part
{"1checkupstagehandshakeupstreamerranterredcaperred2y9e3w", ErrInvalidSeparatorIndex(0)}, // empty hrp
{"11qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqsqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqc8247j", ErrInvalidLength(91)}, // too long
// Additional test vectors used in bitcoin core
{" 1nwldj5", ErrInvalidCharacter(' ')},
{"\x7f" + "1axkwrx", ErrInvalidCharacter(0x7f)},
{"\x801eym55h", ErrInvalidCharacter(0x80)},
{"an84characterslonghumanreadablepartthatcontainsthenumber1andtheexcludedcharactersbio1569pvx", ErrInvalidLength(91)},
{"pzry9x0s0muk", ErrInvalidSeparatorIndex(-1)},
{"1pzry9x0s0muk", ErrInvalidSeparatorIndex(0)},
{"x1b4n0q5v", ErrNonCharsetChar(98)},
{"li1dgmt3", ErrInvalidSeparatorIndex(2)},
{"de1lg7wt\xff", ErrInvalidCharacter(0xff)},
{"A1G7SGD8", ErrInvalidChecksum{"2uel5l", "g7sgd8"}},
{"10a06t8", ErrInvalidLength(7)},
{"1qzzfhee", ErrInvalidSeparatorIndex(0)},
{"a12UEL5L", ErrMixedCase{}},
{"A12uEL5L", ErrMixedCase{}},
}
for _, test := range tests {
for i, test := range tests {
str := test.str
hrp, decoded, err := bech32.Decode(str)
if !test.valid {
// Invalid string decoding should result in error.
if err == nil {
t.Error("expected decoding to fail for "+
"invalid string %v", test.str)
}
hrp, decoded, err := Decode(str)
if test.expectedError != err {
t.Errorf("%d: expected decoding error %v "+
"instead got %v", i, test.expectedError, err)
continue
}
// Valid string decoding should result in no error.
if err != nil {
t.Errorf("expected string to be valid bech32: %v", err)
// End test case here if a decoding error was expected.
continue
}
// Check that it encodes to the same string
encoded, err := bech32.Encode(hrp, decoded)
encoded, err := Encode(hrp, decoded)
if err != nil {
t.Errorf("encoding failed: %v", err)
}
@ -61,9 +79,236 @@ func TestBech32(t *testing.T) {
// Flip a bit in the string an make sure it is caught.
pos := strings.LastIndexAny(str, "1")
flipped := str[:pos+1] + string((str[pos+1] ^ 1)) + str[pos+2:]
_, _, err = bech32.Decode(flipped)
_, _, err = Decode(flipped)
if err == nil {
t.Error("expected decoding to fail")
}
}
}
// TestCanDecodeUnlimtedBech32 tests whether decoding a large bech32 string works
// when using the DecodeNoLimit version
func TestCanDecodeUnlimtedBech32(t *testing.T) {
input := "11qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqsqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq5kx0yd"
// Sanity check that an input of this length errors on regular Decode()
_, _, err := Decode(input)
if err == nil {
t.Fatalf("Test vector not appropriate")
}
// Try and decode it.
hrp, data, err := DecodeNoLimit(input)
if err != nil {
t.Fatalf("Expected decoding of large string to work. Got error: %v", err)
}
// Verify data for correctness.
if hrp != "1" {
t.Fatalf("Unexpected hrp: %v", hrp)
}
decodedHex := fmt.Sprintf("%x", data)
expected := "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000000000000"
if decodedHex != expected {
t.Fatalf("Unexpected decoded data: %s", decodedHex)
}
}
// BenchmarkEncodeDecodeCycle performs a benchmark for a full encode/decode
// cycle of a bech32 string. It also reports the allocation count, which we
// expect to be 2 for a fully optimized cycle.
func BenchmarkEncodeDecodeCycle(b *testing.B) {
// Use a fixed, 49-byte raw data for testing.
inputData, err := hex.DecodeString("cbe6365ddbcda9a9915422c3f091c13f8c7b2f263b8d34067bd12c274408473fa764871c9dd51b1bb34873b3473b633ed1")
if err != nil {
b.Fatalf("failed to initialize input data: %v", err)
}
// Convert this into a 79-byte, base 32 byte slice.
base32Input, err := ConvertBits(inputData, 8, 5, true)
if err != nil {
b.Fatalf("failed to convert input to 32 bits-per-element: %v", err)
}
// Use a fixed hrp for the tests. This should generate an encoded bech32
// string of size 90 (the maximum allowed by BIP-173).
hrp := "bc"
// Begin the benchmark. Given that we test one roundtrip per iteration
// (that is, one Encode() and one Decode() operation), we expect at most
// 2 allocations per reported test op.
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
str, err := Encode(hrp, base32Input)
if err != nil {
b.Fatalf("failed to encode input: %v", err)
}
_, _, err = Decode(str)
if err != nil {
b.Fatalf("failed to decode string: %v", err)
}
}
}
// TestConvertBits tests whether base conversion works using TestConvertBits().
func TestConvertBits(t *testing.T) {
tests := []struct {
input string
output string
fromBits uint8
toBits uint8
pad bool
}{
// Trivial empty conversions.
{"", "", 8, 5, false},
{"", "", 8, 5, true},
{"", "", 5, 8, false},
{"", "", 5, 8, true},
// Conversions of 0 value with/without padding.
{"00", "00", 8, 5, false},
{"00", "0000", 8, 5, true},
{"0000", "00", 5, 8, false},
{"0000", "0000", 5, 8, true},
// Testing when conversion ends exactly at the byte edge. This makes
// both padded and unpadded versions the same.
{"0000000000", "0000000000000000", 8, 5, false},
{"0000000000", "0000000000000000", 8, 5, true},
{"0000000000000000", "0000000000", 5, 8, false},
{"0000000000000000", "0000000000", 5, 8, true},
// Conversions of full byte sequences.
{"ffffff", "1f1f1f1f1e", 8, 5, true},
{"1f1f1f1f1e", "ffffff", 5, 8, false},
{"1f1f1f1f1e", "ffffff00", 5, 8, true},
// Sample random conversions.
{"c9ca", "190705", 8, 5, false},
{"c9ca", "19070500", 8, 5, true},
{"19070500", "c9ca", 5, 8, false},
{"19070500", "c9ca00", 5, 8, true},
// Test cases tested on TestConvertBitsFailures with their corresponding
// fixes.
{"ff", "1f1c", 8, 5, true},
{"1f1c10", "ff20", 5, 8, true},
// Large conversions.
{
"cbe6365ddbcda9a9915422c3f091c13f8c7b2f263b8d34067bd12c274408473fa764871c9dd51b1bb34873b3473b633ed1",
"190f13030c170e1b1916141a13040a14040b011f01040e01071e0607160b1906070e06130801131b1a0416020e110008081c1f1a0e19040703120e1d0a06181b160d0407070c1a07070d11131d1408",
8, 5, true,
},
{
"190f13030c170e1b1916141a13040a14040b011f01040e01071e0607160b1906070e06130801131b1a0416020e110008081c1f1a0e19040703120e1d0a06181b160d0407070c1a07070d11131d1408",
"cbe6365ddbcda9a9915422c3f091c13f8c7b2f263b8d34067bd12c274408473fa764871c9dd51b1bb34873b3473b633ed100",
5, 8, true,
},
}
for i, tc := range tests {
input, err := hex.DecodeString(tc.input)
if err != nil {
t.Fatalf("invalid test input data: %v", err)
}
expected, err := hex.DecodeString(tc.output)
if err != nil {
t.Fatalf("invalid test output data: %v", err)
}
actual, err := ConvertBits(input, tc.fromBits, tc.toBits, tc.pad)
if err != nil {
t.Fatalf("test case %d failed: %v", i, err)
}
if !bytes.Equal(actual, expected) {
t.Fatalf("test case %d has wrong output; expected=%x actual=%x",
i, expected, actual)
}
}
}
// TestConvertBitsFailures tests for the expected conversion failures of
// ConvertBits().
func TestConvertBitsFailures(t *testing.T) {
tests := []struct {
input string
fromBits uint8
toBits uint8
pad bool
err error
}{
// Not enough output bytes when not using padding.
{"ff", 8, 5, false, ErrInvalidIncompleteGroup{}},
{"1f1c10", 5, 8, false, ErrInvalidIncompleteGroup{}},
// Unsupported bit conversions.
{"", 0, 5, false, ErrInvalidBitGroups{}},
{"", 10, 5, false, ErrInvalidBitGroups{}},
{"", 5, 0, false, ErrInvalidBitGroups{}},
{"", 5, 10, false, ErrInvalidBitGroups{}},
}
for i, tc := range tests {
input, err := hex.DecodeString(tc.input)
if err != nil {
t.Fatalf("invalid test input data: %v", err)
}
_, err = ConvertBits(input, tc.fromBits, tc.toBits, tc.pad)
if err != tc.err {
t.Fatalf("test case %d failure: expected '%v' got '%v'", i,
tc.err, err)
}
}
}
// BenchmarkConvertBitsDown benchmarks the speed and memory allocation behavior
// of ConvertBits when converting from a higher base into a lower base (e.g. 8
// => 5).
//
// Only a single allocation is expected, which is used for the output array.
func BenchmarkConvertBitsDown(b *testing.B) {
// Use a fixed, 49-byte raw data for testing.
inputData, err := hex.DecodeString("cbe6365ddbcda9a9915422c3f091c13f8c7b2f263b8d34067bd12c274408473fa764871c9dd51b1bb34873b3473b633ed1")
if err != nil {
b.Fatalf("failed to initialize input data: %v", err)
}
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
_, err := ConvertBits(inputData, 8, 5, true)
if err != nil {
b.Fatalf("error converting bits: %v", err)
}
}
}
// BenchmarkConvertBitsDown benchmarks the speed and memory allocation behavior
// of ConvertBits when converting from a lower base into a higher base (e.g. 5
// => 8).
//
// Only a single allocation is expected, which is used for the output array.
func BenchmarkConvertBitsUp(b *testing.B) {
// Use a fixed, 79-byte raw data for testing.
inputData, err := hex.DecodeString("190f13030c170e1b1916141a13040a14040b011f01040e01071e0607160b1906070e06130801131b1a0416020e110008081c1f1a0e19040703120e1d0a06181b160d0407070c1a07070d11131d1408")
if err != nil {
b.Fatalf("failed to initialize input data: %v", err)
}
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
_, err := ConvertBits(inputData, 8, 5, true)
if err != nil {
b.Fatalf("error converting bits: %v", err)
}
}
}

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// Copyright (c) 2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package bech32
import (
"fmt"
)
// ErrMixedCase is returned when the bech32 string has both lower and uppercase
// characters.
type ErrMixedCase struct{}
func (e ErrMixedCase) Error() string {
return "string not all lowercase or all uppercase"
}
// ErrInvalidBitGroups is returned when conversion is attempted between byte
// slices using bit-per-element of unsupported value.
type ErrInvalidBitGroups struct{}
func (e ErrInvalidBitGroups) Error() string {
return "only bit groups between 1 and 8 allowed"
}
// ErrInvalidIncompleteGroup is returned when then byte slice used as input has
// data of wrong length.
type ErrInvalidIncompleteGroup struct{}
func (e ErrInvalidIncompleteGroup) Error() string {
return "invalid incomplete group"
}
// ErrInvalidLength is returned when the bech32 string has an invalid length
// given the BIP-173 defined restrictions.
type ErrInvalidLength int
func (e ErrInvalidLength) Error() string {
return fmt.Sprintf("invalid bech32 string length %d", int(e))
}
// ErrInvalidCharacter is returned when the bech32 string has a character
// outside the range of the supported charset.
type ErrInvalidCharacter rune
func (e ErrInvalidCharacter) Error() string {
return fmt.Sprintf("invalid character in string: '%c'", rune(e))
}
// ErrInvalidSeparatorIndex is returned when the separator character '1' is
// in an invalid position in the bech32 string.
type ErrInvalidSeparatorIndex int
func (e ErrInvalidSeparatorIndex) Error() string {
return fmt.Sprintf("invalid separator index %d", int(e))
}
// ErrNonCharsetChar is returned when a character outside of the specific
// bech32 charset is used in the string.
type ErrNonCharsetChar rune
func (e ErrNonCharsetChar) Error() string {
return fmt.Sprintf("invalid character not part of charset: %v", int(e))
}
// ErrInvalidChecksum is returned when the extracted checksum of the string
// is different than what was expected.
type ErrInvalidChecksum struct {
Expected string
Actual string
}
func (e ErrInvalidChecksum) Error() string {
return fmt.Sprintf("invalid checksum (expected %v got %v)",
e.Expected, e.Actual)
}
// ErrInvalidDataByte is returned when a byte outside the range required for
// conversion into a string was found.
type ErrInvalidDataByte byte
func (e ErrInvalidDataByte) Error() string {
return fmt.Sprintf("invalid data byte: %v", byte(e))
}