Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

150 lines (132 sloc) 4.877 kb
/* vim: set expandtab ts=4 sw=4: */
/*
* You may redistribute this program and/or modify it under the terms of
* the GNU General Public License as published by the Free Software Foundation,
* either version 3 of the License, or (at your option) any later version.
*
* 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/>.
*/
#ifndef Base32_H
#define Base32_H
#include <stdint.h>
/*
* Base32 encode or decode a byte array using the format defined in:
* http://dnscurve.org/in-implement.html
*/
/** Returned by Base32_decode() if the input is not valid base32. */
#define Base32_BAD_INPUT -1
/** Returned by Base32_decode() or Base32_encode() if the output buffer is too small. */
#define Base32_TOO_BIG -2
/**
* Decode a base32 encoded number.
*
* @param output the place to put the decoded bytes.
* This may be modified even if there is a decoding error.
* @param outLength the length of the output array, if the decoded output is longer,
* Base32_TOO_BIG will be returned.
* @param in the buffer holding the base32 encoded number.
* @param inputLength the length of the input buffer.
* @return the length of the output if all goes well, Base32_BAD_INPUT if the input
* is not valid base32, or Base32_TOO_BIG if the output buffer is not large
* enough to handle the output.
*/
static inline int Base32_decode(uint8_t* output,
const uint32_t outLength,
const uint8_t* in,
const uint32_t inputLength)
{
// Maps ascii character inputs to the numbers
// Invalid characters are represented by 99
static const uint8_t numForAscii[] =
{
99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,
99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,
99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,99,99,99,99,99,99,
99,99,10,11,12,99,13,14,15,99,16,17,18,19,20,99,
21,22,23,24,25,26,27,28,29,30,31,99,99,99,99,99,
99,99,10,11,12,99,13,14,15,99,16,17,18,19,20,99,
21,22,23,24,25,26,27,28,29,30,31,99,99,99,99,99
};
uint32_t outIndex = 0;
uint32_t inputIndex = 0;
uint32_t nextByte = 0;
uint32_t bits = 0;
while (inputIndex < inputLength) {
if (in[inputIndex] & 0x80) {
return Base32_BAD_INPUT;
}
const uint8_t b = numForAscii[in[inputIndex++]];
if (b > 31) {
return Base32_BAD_INPUT;
}
nextByte |= ((unsigned) b) << bits;
bits += 5;
if (bits >= 8) {
if (outIndex >= outLength) {
return Base32_TOO_BIG;
}
output[outIndex++] = nextByte;
bits -= 8;
nextByte >>= 8;
}
}
if (bits >= 5 || nextByte) {
return Base32_BAD_INPUT;
}
return outIndex;
}
/**
* Base32 encode a number.
*
* @param output the place to put the base32 encoded output.
* This may be modified even if there is a encoding error.
* @param outLength the length of the output array, if the encoded output is longer,
* Base32_TOO_BIG will be returned.
* @param in the buffer holding the bytes to encode.
* @param inputLength the length of the input buffer.
* @return the length of the output if all goes well,
* or Base32_TOO_BIG if the output buffer is not large enough to handle the output.
*/
static inline int Base32_encode(uint8_t* output,
const uint32_t outputLength,
const uint8_t* in,
const uint32_t inputLength)
{
uint32_t outIndex = 0;
uint32_t inIndex = 0;
uint32_t work = 0;
uint32_t bits = 0;
static const uint8_t* kChars = (uint8_t*) "0123456789bcdfghjklmnpqrstuvwxyz";
while (inIndex < inputLength) {
work |= ((unsigned) in[inIndex++]) << bits;
bits += 8;
while (bits >= 5) {
if (outIndex >= outputLength) {
return Base32_TOO_BIG;
}
output[outIndex++] = kChars[work & 31];
bits -= 5;
work >>= 5;
}
}
if (bits) {
if (outIndex >= outputLength) {
return Base32_TOO_BIG;
}
output[outIndex++] = kChars[work & 31];
bits -= 5;
work >>= 5;
}
if (outIndex < outputLength) {
output[outIndex] = '\0';
}
return outIndex;
}
#endif
Jump to Line
Something went wrong with that request. Please try again.