xxtea加密算法-忘记是从哪里看到的了

#!/usr/bin/python
# -*- coding:utf-8 -*-

import struct

def btea(v, n, k): #xxtea加密算法
MX = lambda: ((z>>5)^(y<<2)) + ((y>>3)^(z<<4))^(sum^y) + (k[(p & 3)^e]^z)
u32 = lambda x: x & 0xffffffff

y = v[0]
sum = 0
DELTA = 0x9e3779b9
if n > 1:
z = v[n-1]
q = 6 + 52 / n
while q > 0:
q -= 1
sum = u32(sum + DELTA)
e = u32(sum >> 2) & 3
p = 0
while p < n - 1:
y = v[p+1]
z = v[p] = u32(v[p] + MX())
p += 1
y = v[0]
z = v[n-1] = u32(v[n-1] + MX())
return True
elif n < -1:
n = -n
q = 6 + 52 / n
sum = u32(q * DELTA)
while sum != 0:
e = u32(sum >> 2) & 3
p = n - 1
while p > 0:
z = v[p-1]
y = v[p] = u32(v[p] - MX())
p -= 1
z = v[n-1]
y = v[0] = u32(v[0] - MX())
sum = u32(sum - DELTA)
return True
return False

if __name__ == '__main__': #简单试验
print "key", "1234567890123456"
key = struct.unpack("=iiii", "1234567890123456")
v = [110, 111, 112, 113]
print v
btea(v, 4, key)
print v
btea(v, -4, key)
print v

admin$ python xxtea.py
key 1234567890123456
[110, 111, 112, 113]
[2210921364, 249748794, 3317857568, 1737089717]
[110, 111, 112, 113]
admin$