django/base/dependencies/crypto.py

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Python
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2023-12-05 14:46:34 +00:00
CHARSET = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l'
def polymod(values):
chk = 1
generator = [
(0x01, 0x98f2bc8e61),
(0x02, 0x79b76d99e2),
(0x04, 0xf33e5fb3c4),
(0x08, 0xae2eabe2a8),
(0x10, 0x1e4f43e470)]
for value in values:
top = chk >> 35
chk = ((chk & 0x07ffffffff) << 5) ^ value
for i in generator:
if top & i[0] != 0:
chk ^= i[1]
return chk ^ 1
def prefix_expand(prefix):
return [ord(x) & 0x1f for x in prefix] + [0]
def calculate_checksum(prefix, payload):
poly = polymod(prefix_expand(prefix) + payload + [0, 0, 0, 0, 0, 0, 0, 0])
out = list()
for i in range(8):
out.append((poly >> 5 * (7 - i)) & 0x1f)
return out
def verify_checksum(prefix, payload):
return polymod(prefix_expand(prefix) + payload) == 0
def b32decode(inputs):
out = list()
for letter in inputs:
out.append(CHARSET.find(letter))
return out
def b32encode(inputs):
out = ''
for char_code in inputs:
out += CHARSET[char_code]
return out
def convertbits(data, frombits, tobits, pad=True):
acc = 0
bits = 0
ret = []
maxv = (1 << tobits) - 1
max_acc = (1 << (frombits + tobits - 1)) - 1
for value in data:
if value < 0 or (value >> frombits):
return None
acc = ((acc << frombits) | value) & max_acc
bits += frombits
while bits >= tobits:
bits -= tobits
ret.append((acc >> bits) & maxv)
if pad:
if bits:
ret.append((acc << (tobits - bits)) & maxv)
elif bits >= frombits or ((acc << (tobits - bits)) & maxv):
return None
return ret