Here is a patch for the maui checksum algorithm implemented without seeing
the actual code.
Index: src/utils/pseudoDes.py
===================================================================
--- src/utils/pseudoDes.py (revision 0)
+++ src/utils/pseudoDes.py (revision 0)
@@ -0,0 +1,57 @@
+#! /usr/bin/env python
+values = { 1:(0xcba4e531, 0x12be4590),
+ 2:(0x537158eb, 0xab54ce58),
+ 3:(0x145cdc3c, 0x6954c7a6),
+ 4:(0x0d3fdeb2, 0x15a2ca46)}
+
+def crc(short, char):
+ short = short & 0xffff
+ char = char & 0xff
+ value = short ^ (char << 8)
+ for i in range(0, 8):
+ if value & 0x8000:
+ value = (value << 1) ^ 4129
+ else:
+ value = value << 1
+ return value & 0xffff
+
+def pseudoDes(in1, in2):
+ for i in range(1, 5):
+ in1 = in1 & 0xffffffff
+ in2 = in2 & 0xffffffff
+ (value1, value2) = values[i]
+
+ out1 = in2
+ tmp2 = in2 ^ value1
+ tmp1 = ((tmp2 & 0xffff)*(tmp2 & 0xffff)) + ((~((tmp2 >> 16)*(tmp2
>> 16))) & 0xffffffff)
+ tmp1 = tmp1 & 0xffffffff
+ out2 = in1 ^ ((((tmp1 >> 16) | ((tmp1 & 0xffff) << 16)) ^ value2)
+ ((tmp2 & 0xffff) * (tmp2 >> 16)))
+
+ in1, in2 = out1, out2
+ out1 = 0xffffffff & out1
+ out2 = 0xffffffff & out2
+ return out1, out2
+
+def generateKey(msg, key):
+ crcValue = 0
+ for char in msg:
+ crcValue = crc(crcValue, ord(char))
+ left, right = pseudoDes(crcValue, key)
+ return (left << 32) | right
+
+if __name__ == '__main__':
+ msg = 'I am not a crook'
+ key = 35005211
+ print hex(generateKey(msg, key))
+ msg = 'Hello World!'
+ key = 521595368
+ print hex(generateKey(msg, key))
+ msg = 'pseudo des'
+ key = 294702567
+ print hex(generateKey(msg, key))
+ msg = 'copyright infringement'
+ key = 1726956429
+ print hex(generateKey(msg, key))
+ msg = 'whiteboard cowboy'
+ key = 336465782
+ print hex(generateKey(msg, key))
