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import sys
delta_asso = [0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00,0x00, 0x00, 0x00, 0x0F, 0x00, 0x0F]
check_asso = [0x0D, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x03, 0x07, 0x0B, 0x0B, 0x0B, 0x0F]
delta_values =[(0x00), (0x00), (0x00), (0x13), (0x04), (0xBF), (0xBF), (0xB9), (0xB9), (0x00), (0x10), (0xC3), (0xBF), (0xBF), (0xB9), (0xB9)]
check_values = [(0x80), (0x80), (0x80), (0x80), (0xCF), (0xBF), (0xD5), (0xA6), (0xB5), (0x86), (0xD1), (0x80), (0xB1), (0x80), (0x91), (0x80)]
valid = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
def safechr(i):
if i < 32:
return '.'
if i > 127:
return '?'
return chr(i)
def safehex(x):
return "0x{0:2x}".format(x)
def to_signed(x):
if(x >= 128):
return x - 256
return x
def to_unsigned(x):
if(x < 0):
return x + 256
return x
def sat(x, y):
x = to_signed(x)
y = to_signed(y)
z = x + y
if(z > 127):
return 127
if(z < -128):
return to_unsigned(-128)
return to_unsigned(z)
def lookup(table, index):
print("looking up ", hex(index))
if(index >= 128):
return 0
return table[index&0xf]
def quietlookup(table, index):
if(index >= 128):
return 0
return table[index&0xf]
def process(src):
shifted = (src >> 3)%256
delta_hash = (lookup(delta_asso,src) + shifted + 1) >> 1
check_hash = (lookup(check_asso,src) + shifted + 1) >> 1
out = sat(lookup(delta_values,delta_hash), src)
chk = sat(lookup(check_values,check_hash), src)
mask = chk & 0x80
return (out, mask)
def processquiet(src):
shifted = (src >> 3)%256
delta_hash = (quietlookup(delta_asso,src) + shifted + 1) >> 1
check_hash = (quietlookup(check_asso,src) + shifted + 1) >> 1
out = sat(quietlookup(delta_values,delta_hash), src)
chk = sat(quietlookup(check_values,check_hash), src)
mask = chk & 0x80
return (out, mask)
def is_ok(i):
out, mask = processquiet(i)
if mask == 0:
return 1
return 0
def computestring():
s = ""
for i in range(256):
out, mask = processquiet(i)
if(mask == 0):
s += safechr(i)
return s
print(computestring() + " " + str(len(computestring())))
def print_layout():
t={}
for i in range(256):
src = i
shifted = (src >> 3)%256
check_hash = (quietlookup(check_asso,src) + shifted + 1) >> 1
if check_hash not in t:
t[check_hash] = []
t[check_hash].append(i)
for check_hash in range(16):
if check_hash in t:
off = quietlookup(check_values,check_hash)
print(hex(check_hash), hex(off), end="")
print("\t", " ".join([" "+safechr(c) for c in t[check_hash]]))
else:
continue
def is_valid():
t={}
for i in range(256):
src = i
shifted = (src >> 3)%256
check_hash = (quietlookup(check_asso,src) + shifted + 1) >> 1
if check_hash not in t:
t[check_hash] = []
t[check_hash].append(i)
for check_hash in t.keys():
if check_hash in t:
array = t[check_hash]
i = 0
while i < len(array) and valid.find(chr(array[i])) == -1:
i += 1
while i < len(array) and valid.find(chr(array[i])) != -1:
i += 1
while i < len(array) and array[i] >= 128:
i += 1
if i < len(array):
return False
else:
continue
return True
print_layout()
print(is_valid())
def is_base64(src):
is_base64 = None
for i in range(8):
shifted = (src >> 3)%256
shifted += i << 5
#print("shifted ", hex(shifted))
delta_hash = (quietlookup(delta_asso,src) + shifted + 1) >> 1
#print("delta_hash ", hex(delta_hash))
check_hash = (quietlookup(check_asso,src) + shifted + 1) >> 1
#print("check_hash ", hex(check_hash))
out = sat(quietlookup(delta_values,delta_hash), src)
#print("out ", hex(out))
chk = sat(quietlookup(check_values,check_hash), src)
this_is_base64 = chk & 0x80 == 0
if is_base64 is None:
is_base64 = this_is_base64
else:
if is_base64 != this_is_base64:
print("unexpected")
return None
return is_base64
for i in range(256):
if is_base64(i):
print(chr(i), end=",")
elif is_base64(i) is None:
print("None", hex(i), end=",")
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