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// Copyright (c) 2014-2018, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
#include "base58.h"
#include <assert.h>
#include <string>
#include <vector>
#include "crypto/hash.h"
#include "int-util.h"
#include "varint.h"
namespace tools
{
namespace base58
{
namespace
{
const char alphabet[] = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
const size_t alphabet_size = sizeof(alphabet) - 1;
const size_t encoded_block_sizes[] = {0, 2, 3, 5, 6, 7, 9, 10, 11};
const size_t full_block_size = sizeof(encoded_block_sizes) / sizeof(encoded_block_sizes[0]) - 1;
const size_t full_encoded_block_size = encoded_block_sizes[full_block_size];
const size_t addr_checksum_size = 4;
struct reverse_alphabet
{
reverse_alphabet()
{
m_data.resize(alphabet[alphabet_size - 1] - alphabet[0] + 1, -1);
for (size_t i = 0; i < alphabet_size; ++i)
{
size_t idx = static_cast<size_t>(alphabet[i] - alphabet[0]);
m_data[idx] = static_cast<int8_t>(i);
}
}
int operator()(char letter) const
{
size_t idx = static_cast<size_t>(letter - alphabet[0]);
return idx < m_data.size() ? m_data[idx] : -1;
}
static reverse_alphabet instance;
private:
std::vector<int8_t> m_data;
};
reverse_alphabet reverse_alphabet::instance;
struct decoded_block_sizes
{
decoded_block_sizes()
{
m_data.resize(encoded_block_sizes[full_block_size] + 1, -1);
for (size_t i = 0; i <= full_block_size; ++i)
{
m_data[encoded_block_sizes[i]] = static_cast<int>(i);
}
}
int operator()(size_t encoded_block_size) const
{
assert(encoded_block_size <= full_encoded_block_size);
return m_data[encoded_block_size];
}
static decoded_block_sizes instance;
private:
std::vector<int> m_data;
};
decoded_block_sizes decoded_block_sizes::instance;
uint64_t uint_8be_to_64(const uint8_t* data, size_t size)
{
assert(1 <= size && size <= sizeof(uint64_t));
uint64_t res = 0;
memcpy(reinterpret_cast<uint8_t*>(&res) + sizeof(uint64_t) - size, data, size);
return SWAP64BE(res);
}
void uint_64_to_8be(uint64_t num, size_t size, uint8_t* data)
{
assert(1 <= size && size <= sizeof(uint64_t));
uint64_t num_be = SWAP64BE(num);
memcpy(data, reinterpret_cast<uint8_t*>(&num_be) + sizeof(uint64_t) - size, size);
}
void encode_block(const char* block, size_t size, char* res)
{
assert(1 <= size && size <= full_block_size);
uint64_t num = uint_8be_to_64(reinterpret_cast<const uint8_t*>(block), size);
int i = static_cast<int>(encoded_block_sizes[size]) - 1;
while (0 < num)
{
uint64_t remainder = num % alphabet_size;
num /= alphabet_size;
res[i] = alphabet[remainder];
--i;
}
}
bool decode_block(const char* block, size_t size, char* res)
{
assert(1 <= size && size <= full_encoded_block_size);
int res_size = decoded_block_sizes::instance(size);
if (res_size <= 0)
return false; // Invalid block size
uint64_t res_num = 0;
uint64_t order = 1;
for (size_t i = size - 1; i < size; --i)
{
int digit = reverse_alphabet::instance(block[i]);
if (digit < 0)
return false; // Invalid symbol
uint64_t product_hi;
uint64_t tmp = res_num + mul128(order, digit, &product_hi);
if (tmp < res_num || 0 != product_hi)
return false; // Overflow
res_num = tmp;
order *= alphabet_size; // Never overflows, 58^10 < 2^64
}
if (static_cast<size_t>(res_size) < full_block_size && (UINT64_C(1) << (8 * res_size)) <= res_num)
return false; // Overflow
uint_64_to_8be(res_num, res_size, reinterpret_cast<uint8_t*>(res));
return true;
}
}
std::string encode(const std::string& data)
{
if (data.empty())
return std::string();
size_t full_block_count = data.size() / full_block_size;
size_t last_block_size = data.size() % full_block_size;
size_t res_size = full_block_count * full_encoded_block_size + encoded_block_sizes[last_block_size];
std::string res(res_size, alphabet[0]);
for (size_t i = 0; i < full_block_count; ++i)
{
encode_block(data.data() + i * full_block_size, full_block_size, &res[i * full_encoded_block_size]);
}
if (0 < last_block_size)
{
encode_block(data.data() + full_block_count * full_block_size, last_block_size, &res[full_block_count * full_encoded_block_size]);
}
return res;
}
bool decode(const std::string& enc, std::string& data)
{
if (enc.empty())
{
data.clear();
return true;
}
size_t full_block_count = enc.size() / full_encoded_block_size;
size_t last_block_size = enc.size() % full_encoded_block_size;
int last_block_decoded_size = decoded_block_sizes::instance(last_block_size);
if (last_block_decoded_size < 0)
return false; // Invalid enc length
size_t data_size = full_block_count * full_block_size + last_block_decoded_size;
data.resize(data_size, 0);
for (size_t i = 0; i < full_block_count; ++i)
{
if (!decode_block(enc.data() + i * full_encoded_block_size, full_encoded_block_size, &data[i * full_block_size]))
return false;
}
if (0 < last_block_size)
{
if (!decode_block(enc.data() + full_block_count * full_encoded_block_size, last_block_size,
&data[full_block_count * full_block_size]))
return false;
}
return true;
}
std::string encode_addr(uint64_t tag, const std::string& data)
{
std::string buf = get_varint_data(tag);
buf += data;
crypto::hash hash = crypto::cn_fast_hash(buf.data(), buf.size());
const char* hash_data = reinterpret_cast<const char*>(&hash);
buf.append(hash_data, addr_checksum_size);
return encode(buf);
}
bool decode_addr(const std::string &addr, uint64_t& tag, std::string& data)
{
std::string addr_data;
bool r = decode(addr, addr_data);
if (!r) return false;
if (addr_data.size() <= addr_checksum_size) return false;
std::string checksum(addr_checksum_size, '\0');
checksum = addr_data.substr(addr_data.size() - addr_checksum_size);
addr_data.resize(addr_data.size() - addr_checksum_size);
crypto::hash hash = crypto::cn_fast_hash(addr_data.data(), addr_data.size());
std::string expected_checksum(reinterpret_cast<const char*>(&hash), addr_checksum_size);
if (expected_checksum != checksum) return false;
int read = tools::read_varint(addr_data.begin(), addr_data.end(), tag);
if (read <= 0) return false;
data = addr_data.substr(read);
return true;
}
}
}
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