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xxtea.c
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xxtea.c
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/**********************************************************\
| |
| xxtea.c |
| |
| XXTEA encryption algorithm library for C. |
| |
| Encryption Algorithm Authors: |
| David J. Wheeler |
| Roger M. Needham |
| |
| Code Authors: Chen fei <[email protected]> |
| Ma Bingyao <[email protected]> |
| LastModified: Feb 7, 2016 |
| |
\**********************************************************/
#include "xxtea.h"
#include <string.h>
#if defined(_MSC_VER) && _MSC_VER < 1600
typedef unsigned __int8 uint8_t;
typedef unsigned __int32 uint32_t;
#else
#if defined(__FreeBSD__) && __FreeBSD__ < 5
/* FreeBSD 4 doesn't have stdint.h file */
#include <inttypes.h>
#else
#include <stdint.h>
#endif
#endif
#include <sys/types.h> /* This will likely define BYTE_ORDER */
#ifndef BYTE_ORDER
#if (BSD >= 199103)
# include <machine/endian.h>
#else
#if defined(linux) || defined(__linux__)
# include <endian.h>
#else
#define LITTLE_ENDIAN 1234 /* least-significant byte first (vax, pc) */
#define BIG_ENDIAN 4321 /* most-significant byte first (IBM, net) */
#define PDP_ENDIAN 3412 /* LSB first in word, MSW first in long (pdp)*/
#if defined(__i386__) || defined(__x86_64__) || defined(__amd64__) || \
defined(vax) || defined(ns32000) || defined(sun386) || \
defined(MIPSEL) || defined(_MIPSEL) || defined(BIT_ZERO_ON_RIGHT) || \
defined(__alpha__) || defined(__alpha)
#define BYTE_ORDER LITTLE_ENDIAN
#endif
#if defined(sel) || defined(pyr) || defined(mc68000) || defined(sparc) || \
defined(is68k) || defined(tahoe) || defined(ibm032) || defined(ibm370) || \
defined(MIPSEB) || defined(_MIPSEB) || defined(_IBMR2) || defined(DGUX) ||\
defined(apollo) || defined(__convex__) || defined(_CRAY) || \
defined(__hppa) || defined(__hp9000) || \
defined(__hp9000s300) || defined(__hp9000s700) || \
defined (BIT_ZERO_ON_LEFT) || defined(m68k) || defined(__sparc)
#define BYTE_ORDER BIG_ENDIAN
#endif
#endif /* linux */
#endif /* BSD */
#endif /* BYTE_ORDER */
#ifndef BYTE_ORDER
#ifdef __BYTE_ORDER
#if defined(__LITTLE_ENDIAN) && defined(__BIG_ENDIAN)
#ifndef LITTLE_ENDIAN
#define LITTLE_ENDIAN __LITTLE_ENDIAN
#endif
#ifndef BIG_ENDIAN
#define BIG_ENDIAN __BIG_ENDIAN
#endif
#if (__BYTE_ORDER == __LITTLE_ENDIAN)
#define BYTE_ORDER LITTLE_ENDIAN
#else
#define BYTE_ORDER BIG_ENDIAN
#endif
#endif
#endif
#endif
#define MX (((z >> 5) ^ (y << 2)) + ((y >> 3) ^ (z << 4))) ^ ((sum ^ y) + (key[(p & 3) ^ e] ^ z))
#define DELTA 0x9e3779b9
#define FIXED_KEY \
size_t i;\
uint8_t fixed_key[16];\
memcpy(fixed_key, key, 16);\
for (i = 0; (i < 16) && (fixed_key[i] != 0); ++i);\
for (++i; i < 16; ++i) fixed_key[i] = 0;\
static uint32_t * xxtea_to_uint_array(const uint8_t * data, size_t len, int inc_len, size_t * out_len) {
uint32_t *out;
#if !(defined(BYTE_ORDER) && (BYTE_ORDER == LITTLE_ENDIAN))
size_t i;
#endif
size_t n;
n = (((len & 3) == 0) ? (len >> 2) : ((len >> 2) + 1));
if (inc_len) {
out = (uint32_t *)calloc(n + 1, sizeof(uint32_t));
if (!out) return NULL;
out[n] = (uint32_t)len;
*out_len = n + 1;
}
else {
out = (uint32_t *)calloc(n, sizeof(uint32_t));
if (!out) return NULL;
*out_len = n;
}
#if defined(BYTE_ORDER) && (BYTE_ORDER == LITTLE_ENDIAN)
memcpy(out, data, len);
#else
for (i = 0; i < len; ++i) {
out[i >> 2] |= (uint32_t)data[i] << ((i & 3) << 3);
}
#endif
return out;
}
static uint8_t * xxtea_to_ubyte_array(const uint32_t * data, size_t len, int inc_len, size_t * out_len) {
uint8_t *out;
#if !(defined(BYTE_ORDER) && (BYTE_ORDER == LITTLE_ENDIAN))
size_t i;
#endif
size_t m, n;
n = len << 2;
if (inc_len) {
m = data[len - 1];
n -= 4;
if ((m < n - 3) || (m > n)) return NULL;
n = m;
}
out = (uint8_t *)malloc(n + 1);
#if defined(BYTE_ORDER) && (BYTE_ORDER == LITTLE_ENDIAN)
memcpy(out, data, n);
#else
for (i = 0; i < n; ++i) {
out[i] = (uint8_t)(data[i >> 2] >> ((i & 3) << 3));
}
#endif
out[n] = '\0';
*out_len = n;
return out;
}
static uint32_t * xxtea_uint_encrypt(uint32_t * data, size_t len, uint32_t * key) {
uint32_t n = (uint32_t)len - 1;
uint32_t z = data[n], y, p, q = 6 + 52 / (n + 1), sum = 0, e;
if (n < 1) return data;
while (0 < q--) {
sum += DELTA;
e = sum >> 2 & 3;
for (p = 0; p < n; p++) {
y = data[p + 1];
z = data[p] += MX;
}
y = data[0];
z = data[n] += MX;
}
return data;
}
static uint32_t * xxtea_uint_decrypt(uint32_t * data, size_t len, uint32_t * key) {
uint32_t n = (uint32_t)len - 1;
uint32_t z, y = data[0], p, q = 6 + 52 / (n + 1), sum = q * DELTA, e;
if (n < 1) return data;
while (sum != 0) {
e = sum >> 2 & 3;
for (p = n; p > 0; p--) {
z = data[p - 1];
y = data[p] -= MX;
}
z = data[n];
y = data[0] -= MX;
sum -= DELTA;
}
return data;
}
static uint8_t * xxtea_ubyte_encrypt(const uint8_t * data, size_t len, const uint8_t * key, size_t * out_len) {
uint8_t *out;
uint32_t *data_array, *key_array;
size_t data_len, key_len;
if (!len) return NULL;
data_array = xxtea_to_uint_array(data, len, 1, &data_len);
if (!data_array) return NULL;
key_array = xxtea_to_uint_array(key, 16, 0, &key_len);
if (!key_array) {
free(data_array);
return NULL;
}
out = xxtea_to_ubyte_array(xxtea_uint_encrypt(data_array, data_len, key_array), data_len, 0, out_len);
free(data_array);
free(key_array);
return out;
}
static uint8_t * xxtea_ubyte_decrypt(const uint8_t * data, size_t len, const uint8_t * key, size_t * out_len) {
uint8_t *out;
uint32_t *data_array, *key_array;
size_t data_len, key_len;
if (!len) return NULL;
data_array = xxtea_to_uint_array(data, len, 0, &data_len);
if (!data_array) return NULL;
key_array = xxtea_to_uint_array(key, 16, 0, &key_len);
if (!key_array) {
free(data_array);
return NULL;
}
out = xxtea_to_ubyte_array(xxtea_uint_decrypt(data_array, data_len, key_array), data_len, 1, out_len);
free(data_array);
free(key_array);
return out;
}
// public functions
void * xxtea_encrypt(const void * data, size_t len, const void * key, size_t * out_len) {
FIXED_KEY
return xxtea_ubyte_encrypt((const uint8_t *)data, len, fixed_key, out_len);
}
void * xxtea_decrypt(const void * data, size_t len, const void * key, size_t * out_len) {
FIXED_KEY
return xxtea_ubyte_decrypt((const uint8_t *)data, len, fixed_key, out_len);
}