keepassxc/src/core/Base32.cpp
2017-11-12 12:09:35 -06:00

296 lines
8.2 KiB
C++

/*
* Copyright (C) 2017 KeePassXC Team <team@keepassxc.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 or (at your option)
* version 3 of the License.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/* Conforms to RFC 4648. For details, see: https://tools.ietf.org/html/rfc4648
* Use the functions Base32::addPadding/1, Base32::removePadding/1 or
* Base32::sanitizeInput/1 to fix input or output for a particular
* applications (e.g. to use with Google Authenticator).
*/
#include "Base32.h"
constexpr quint64 MASK_40BIT = quint64(0xF8) << 32;
constexpr quint64 MASK_35BIT = quint64(0x7C0000000);
constexpr quint64 MASK_25BIT = quint64(0x1F00000);
constexpr quint64 MASK_20BIT = quint64(0xF8000);
constexpr quint64 MASK_10BIT = quint64(0x3E0);
constexpr char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
constexpr quint8 ALPH_POS_2 = 26;
constexpr quint8 ASCII_2 = static_cast<quint8>('2');
constexpr quint8 ASCII_7 = static_cast<quint8>('7');
constexpr quint8 ASCII_A = static_cast<quint8>('A');
constexpr quint8 ASCII_Z = static_cast<quint8>('Z');
constexpr quint8 ASCII_a = static_cast<quint8>('a');
constexpr quint8 ASCII_z = static_cast<quint8>('z');
constexpr quint8 ASCII_EQ = static_cast<quint8>('=');
QVariant Base32::decode(const QByteArray& encodedData)
{
if (encodedData.size() <= 0) {
return QVariant::fromValue(QByteArray(""));
}
if (encodedData.size() % 8 != 0) {
return QVariant();
}
int nPads = 0;
for (int i = -1; i > -7; --i) {
if ('=' == encodedData[encodedData.size() + i]) {
++nPads;
}
}
int specialOffset;
int nSpecialBytes;
switch (nPads) { // in {0, 1, 3, 4, 6}
case 1:
nSpecialBytes = 4;
specialOffset = 3;
break;
case 3:
nSpecialBytes = 3;
specialOffset = 1;
break;
case 4:
nSpecialBytes = 2;
specialOffset = 4;
break;
case 6:
nSpecialBytes = 1;
specialOffset = 2;
break;
default:
nSpecialBytes = 0;
specialOffset = 0;
}
Q_ASSERT(encodedData.size() > 0);
const int nQuanta = encodedData.size() / 8;
const int nBytes = nSpecialBytes > 0 ? (nQuanta - 1) * 5 + nSpecialBytes : nQuanta * 5;
QByteArray data(nBytes, Qt::Uninitialized);
int i = 0;
int o = 0;
while (i < encodedData.size()) {
quint64 quantum = 0;
int nQuantumBytes = 5;
for (int n = 0; n < 8; ++n) {
auto ch = static_cast<quint8>(encodedData[i++]);
if ((ASCII_A <= ch && ch <= ASCII_Z) || (ASCII_a <= ch && ch <= ASCII_z)) {
ch -= ASCII_A;
if (ch >= ALPH_POS_2) {
ch -= ASCII_a - ASCII_A;
}
} else {
if (ASCII_2 <= ch && ch <= ASCII_7) {
ch -= ASCII_2;
ch += ALPH_POS_2;
} else {
if (ASCII_EQ == ch) {
if (i == encodedData.size()) {
// finished with special quantum
quantum >>= specialOffset;
nQuantumBytes = nSpecialBytes;
}
continue;
} else {
// illegal character
return QVariant();
}
}
}
quantum <<= 5;
quantum |= ch;
}
const int offset = (nQuantumBytes - 1) * 8;
quint64 mask = quint64(0xFF) << offset;
for (int n = offset; n >= 0 && o < nBytes; n -= 8) {
data[o++] = static_cast<char>((quantum & mask) >> n);
mask >>= 8;
}
}
Q_ASSERT(encodedData.size() == i);
Q_ASSERT(nBytes == o);
return QVariant::fromValue(data);
}
QByteArray Base32::encode(const QByteArray& data)
{
if (data.size() < 1) {
return QByteArray();
}
const int nBits = data.size() * 8;
const int rBits = nBits % 40; // in {0, 8, 16, 24, 32}
const int nQuanta = nBits / 40 + (rBits > 0 ? 1 : 0);
const int nBytes = nQuanta * 8;
QByteArray encodedData(nBytes, Qt::Uninitialized);
int i = 0;
int o = 0;
int n;
quint64 mask;
quint64 quantum;
// 40-bits of input per input group
while (i + 5 <= data.size()) {
quantum = 0;
for (n = 32; n >= 0; n -= 8) {
quantum |= (static_cast<quint64>(data[i++]) << n);
}
mask = MASK_40BIT;
int index;
for (n = 35; n >= 0; n -= 5) {
index = (quantum & mask) >> n;
Q_ASSERT(0 <= index && index <= 31);
encodedData[o++] = alphabet[index];
mask >>= 5;
}
}
// < 40-bits of input at final input group
if (i < data.size()) {
Q_ASSERT(8 <= rBits && rBits <= 32);
quantum = 0;
for (n = rBits - 8; n >= 0; n -= 8) {
quantum |= static_cast<quint64>(data[i++]) << n;
}
switch (rBits) {
case 8: // expand to 10 bits
quantum <<= 2;
mask = MASK_10BIT;
n = 5;
break;
case 16: // expand to 20 bits
quantum <<= 4;
mask = MASK_20BIT;
n = 15;
break;
case 24: // expand to 25 bits
quantum <<= 1;
mask = MASK_25BIT;
n = 20;
break;
default: // expand to 35 bits
Q_ASSERT(32 == rBits);
quantum <<= 3;
mask = MASK_35BIT;
n = 30;
}
while (n >= 0) {
int index = (quantum & mask) >> n;
Q_ASSERT(0 <= index && index <= 31);
encodedData[o++] = alphabet[index];
mask >>= 5;
n -= 5;
}
// add pad characters
while (o < encodedData.size()) {
encodedData[o++] = '=';
}
}
Q_ASSERT(data.size() == i);
Q_ASSERT(nBytes == o);
return encodedData;
}
QByteArray Base32::addPadding(const QByteArray& encodedData)
{
if (encodedData.size() <= 0 || encodedData.size() % 8 == 0) {
return encodedData;
}
const int rBytes = encodedData.size() % 8;
// rBytes must be a member of {2, 4, 5, 7}
if (1 == rBytes || 3 == rBytes || 6 == rBytes) {
return encodedData;
}
QByteArray newEncodedData(encodedData);
for (int nPads = 8 - rBytes; nPads > 0; --nPads) {
newEncodedData.append('=');
}
return newEncodedData;
}
QByteArray Base32::removePadding(const QByteArray& encodedData)
{
if (encodedData.size() <= 0 || encodedData.size() % 8 != 0) {
return encodedData; // return same bad input
}
int nPads = 0;
for (int i = -1; i > -7; --i) {
if ('=' == encodedData[encodedData.size() + i]) {
++nPads;
}
}
QByteArray newEncodedData(encodedData);
newEncodedData.remove(encodedData.size() - nPads, nPads);
newEncodedData.resize(encodedData.size() - nPads);
return newEncodedData;
}
QByteArray Base32::sanitizeInput(const QByteArray& encodedData)
{
if (encodedData.size() <= 0) {
return encodedData;
}
QByteArray newEncodedData(encodedData.size(), Qt::Uninitialized);
int i = 0;
for (auto ch : encodedData) {
switch (ch) {
case '0':
newEncodedData[i++] = 'O';
break;
case '1':
newEncodedData[i++] = 'L';
break;
case '8':
newEncodedData[i++] = 'B';
break;
default:
if (('A' <= ch && ch <= 'Z') || ('a' <= ch && ch <= 'z') || ('2' <= ch && ch <= '7')) {
newEncodedData[i++] = ch;
}
}
}
newEncodedData.resize(i);
return addPadding(newEncodedData);
}