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/*
* Base32 Encoding and Decoding
* (C) 2018 Erwan Chaussy
* (C) 2018,2020 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/base32.h>
#include <botan/internal/codec_base.h>
#include <botan/internal/rounding.h>
#include <botan/internal/ct_utils.h>
namespace Botan {
namespace {
class Base32 final
{
public:
static inline std::string name() noexcept
{
return "base32";
}
static inline size_t encoding_bytes_in() noexcept
{
return m_encoding_bytes_in;
}
static inline size_t encoding_bytes_out() noexcept
{
return m_encoding_bytes_out;
}
static inline size_t decoding_bytes_in() noexcept
{
return m_encoding_bytes_out;
}
static inline size_t decoding_bytes_out() noexcept
{
return m_encoding_bytes_in;
}
static inline size_t bits_consumed() noexcept
{
return m_encoding_bits;
}
static inline size_t remaining_bits_before_padding() noexcept
{
return m_remaining_bits_before_padding;
}
static inline size_t encode_max_output(size_t input_length)
{
return (round_up(input_length, m_encoding_bytes_in) / m_encoding_bytes_in) * m_encoding_bytes_out;
}
static inline size_t decode_max_output(size_t input_length)
{
return (round_up(input_length, m_encoding_bytes_out) * m_encoding_bytes_in) / m_encoding_bytes_out;
}
static void encode(char out[8], const uint8_t in[5]) noexcept;
static uint8_t lookup_binary_value(char input) noexcept;
static bool check_bad_char(uint8_t bin, char input, bool ignore_ws);
static void decode(uint8_t* out_ptr, const uint8_t decode_buf[8])
{
out_ptr[0] = (decode_buf[0] << 3) | (decode_buf[1] >> 2);
out_ptr[1] = (decode_buf[1] << 6) | (decode_buf[2] << 1) | (decode_buf[3] >> 4);
out_ptr[2] = (decode_buf[3] << 4) | (decode_buf[4] >> 1);
out_ptr[3] = (decode_buf[4] << 7) | (decode_buf[5] << 2) | (decode_buf[6] >> 3);
out_ptr[4] = (decode_buf[6] << 5) | decode_buf[7];
}
static inline size_t bytes_to_remove(size_t final_truncate)
{
return final_truncate ? (final_truncate / 2) + 1 : 0;
}
private:
static const size_t m_encoding_bits = 5;
static const size_t m_remaining_bits_before_padding = 6;
static const size_t m_encoding_bytes_in = 5;
static const size_t m_encoding_bytes_out = 8;
};
namespace {
char lookup_base32_char(uint8_t x)
{
BOTAN_DEBUG_ASSERT(x < 32);
const auto in_AZ = CT::Mask<uint8_t>::is_lt(x, 26);
const char c_AZ = 'A' + x;
const char c_27 = '2' + (x - 26);
return in_AZ.select(c_AZ, c_27);
}
}
//static
void Base32::encode(char out[8], const uint8_t in[5]) noexcept
{
const uint8_t b0 = (in[0] & 0xF8) >> 3;
const uint8_t b1 = ((in[0] & 0x07) << 2) | (in[1] >> 6);
const uint8_t b2 = ((in[1] & 0x3E) >> 1);
const uint8_t b3 = ((in[1] & 0x01) << 4) | (in[2] >> 4);
const uint8_t b4 = ((in[2] & 0x0F) << 1) | (in[3] >> 7);
const uint8_t b5 = ((in[3] & 0x7C) >> 2);
const uint8_t b6 = ((in[3] & 0x03) << 3) | (in[4] >> 5);
const uint8_t b7 = in[4] & 0x1F;
out[0] = lookup_base32_char(b0);
out[1] = lookup_base32_char(b1);
out[2] = lookup_base32_char(b2);
out[3] = lookup_base32_char(b3);
out[4] = lookup_base32_char(b4);
out[5] = lookup_base32_char(b5);
out[6] = lookup_base32_char(b6);
out[7] = lookup_base32_char(b7);
}
//static
uint8_t Base32::lookup_binary_value(char input) noexcept
{
const uint8_t c = static_cast<uint8_t>(input);
const auto is_alpha_upper = CT::Mask<uint8_t>::is_within_range(c, uint8_t('A'), uint8_t('Z'));
const auto is_decimal = CT::Mask<uint8_t>::is_within_range(c, uint8_t('2'), uint8_t('7'));
const auto is_equal = CT::Mask<uint8_t>::is_equal(c, uint8_t('='));
const auto is_whitespace = CT::Mask<uint8_t>::is_any_of(c, {
uint8_t(' '), uint8_t('\t'), uint8_t('\n'), uint8_t('\r')
});
const uint8_t c_upper = c - uint8_t('A');
const uint8_t c_decim = c - uint8_t('2') + 26;
uint8_t ret = 0xFF; // default value
ret = is_alpha_upper.select(c_upper, ret);
ret = is_decimal.select(c_decim, ret);
ret = is_equal.select(0x81, ret);
ret = is_whitespace.select(0x80, ret);
return ret;
}
//static
bool Base32::check_bad_char(uint8_t bin, char input, bool ignore_ws)
{
if(bin <= 0x1F)
{
return true;
}
else if(!(bin == 0x81 || (bin == 0x80 && ignore_ws)))
{
std::string bad_char(1, input);
if(bad_char == "\t")
{ bad_char = "\\t"; }
else if(bad_char == "\n")
{ bad_char = "\\n"; }
else if(bad_char == "\r")
{ bad_char = "\\r"; }
throw Invalid_Argument(
std::string("base32_decode: invalid base32 character '") +
bad_char + "'");
}
return false;
}
}
size_t base32_encode(char out[],
const uint8_t in[],
size_t input_length,
size_t& input_consumed,
bool final_inputs)
{
return base_encode(Base32(), out, in, input_length, input_consumed, final_inputs);
}
std::string base32_encode(const uint8_t input[],
size_t input_length)
{
return base_encode_to_string(Base32(), input, input_length);
}
size_t base32_decode(uint8_t out[],
const char in[],
size_t input_length,
size_t& input_consumed,
bool final_inputs,
bool ignore_ws)
{
return base_decode(Base32(), out, in, input_length, input_consumed, final_inputs, ignore_ws);
}
size_t base32_decode(uint8_t output[],
const char input[],
size_t input_length,
bool ignore_ws)
{
return base_decode_full(Base32(), output, input, input_length, ignore_ws);
}
size_t base32_decode(uint8_t output[],
const std::string& input,
bool ignore_ws)
{
return base32_decode(output, input.data(), input.length(), ignore_ws);
}
secure_vector<uint8_t> base32_decode(const char input[],
size_t input_length,
bool ignore_ws)
{
return base_decode_to_vec<secure_vector<uint8_t>>(Base32(), input, input_length, ignore_ws);
}
secure_vector<uint8_t> base32_decode(const std::string& input,
bool ignore_ws)
{
return base32_decode(input.data(), input.size(), ignore_ws);
}
}
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