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cocos2d-x implementation of XXTEA
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#!/usr/bin/env python | |
# -*- coding: UTF-8 -*- | |
import struct | |
_DELTA = 0x9E3779B9 | |
def _long2str(v, w): | |
n = (len(v) - 1) << 2 | |
if w: | |
m = v[-1] | |
if (m < n - 3) or (m > n): return '' | |
n = m | |
s = struct.pack('<%iL' % len(v), *v) | |
return s[0:n] if w else s | |
def _str2long(s, w): | |
n = len(s) | |
m = (4 - (n & 3) & 3) + n | |
s = s.ljust(m, b"\0") | |
v = list(struct.unpack('<%iL' % (m >> 2), s)) | |
if w: v.append(n) | |
return v | |
def do_xxtea_encrypt(str, key): | |
if str == '': return str | |
v = _str2long(str, True) | |
k = _str2long(key.ljust(16, "\0"), False) | |
n = len(v) - 1 | |
z = v[n] | |
y = v[0] | |
sum = 0 | |
q = 6 + 52 // (n + 1) | |
while q > 0: | |
sum = (sum + _DELTA) & 0xffffffff | |
e = sum >> 2 & 3 | |
for p in xrange(n): | |
y = v[p + 1] | |
v[p] = (v[p] + ((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z))) & 0xffffffff | |
z = v[p] | |
y = v[0] | |
v[n] = (v[n] + ((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[n & 3 ^ e] ^ z))) & 0xffffffff | |
z = v[n] | |
q -= 1 | |
return _long2str(v, False) | |
def do_xxtea_decrypt(str, key): | |
if str == b'': return str | |
v = _str2long(str, False) | |
k = _str2long(key.ljust(16, b"\0"), False) | |
n = len(v) - 1 | |
z = v[n] | |
y = v[0] | |
q = 6 + 52 // (n + 1) | |
sum = (q * _DELTA) & 0xffffffff | |
while (sum != 0): | |
e = sum >> 2 & 3 | |
for p in range(n, 0, -1): | |
z = v[p - 1] | |
v[p] = (v[p] - ((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z))) & 0xffffffff | |
y = v[p] | |
z = v[n] | |
v[0] = (v[0] - ((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[0 & 3 ^ e] ^ z))) & 0xffffffff | |
y = v[0] | |
sum = (sum - _DELTA) & 0xffffffff | |
return _long2str(v, True) | |
def fix_key_length(key): | |
key = key + ('\x00' * (16 - len(key))) | |
return key | |
def decrypt(str, key): | |
if len(key) < 16: | |
res = do_xxtea_decrypt(str, fix_key_length(key)) | |
else: | |
res = do_xxtea_decrypt(str, key) | |
def encrypt(str, key): | |
if len(key) < 16: | |
res = do_xxtea_encrypt(str, fix_key_length(key)) | |
else: | |
res = do_xxtea_encrypt(str, key) |
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