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-rw-r--r--freestyle_hid/_freestyle_encryption.py67
1 files changed, 45 insertions, 22 deletions
diff --git a/freestyle_hid/_freestyle_encryption.py b/freestyle_hid/_freestyle_encryption.py
index 0461cb8..a0268eb 100644
--- a/freestyle_hid/_freestyle_encryption.py
+++ b/freestyle_hid/_freestyle_encryption.py
@@ -6,7 +6,7 @@
class SpeckEncrypt:
def __init__(self, key):
# Perform key expansion and store the round keys
- self.key = key & ((2 ** 128) - 1)
+ self.key = key & ((2**128) - 1)
self.key_schedule = [self.key & 0xFFFFFFFF]
key_buf = [(self.key >> (x * 32)) & 0xFFFFFFFF for x in range(1, 4)]
for x in range(26):
@@ -58,13 +58,19 @@ class SpeckEncrypt:
def encrypt(self, iv, plain):
plain = bytearray(plain)
input_length = len(plain)
- plain.extend(bytes(b'\x00' * (8 - (input_length % 8))))
- iv = int.from_bytes(iv.to_bytes(8, byteorder='big'), byteorder='little', signed=False)
+ plain.extend(bytes(b"\x00" * (8 - (input_length % 8))))
+ iv = int.from_bytes(
+ iv.to_bytes(8, byteorder="big"), byteorder="little", signed=False
+ )
output = bytearray()
for i in range(len(plain) // 8):
k = self.encrypt_block(iv)
- res = k ^ int.from_bytes(plain[i*8:i*8+8], byteorder='little', signed=False)
- output.extend(int.to_bytes(res, 8, byteorder='little', signed=False))
+ slice_start = i * 8
+ slice_end = slice_start + 8
+ res = k ^ int.from_bytes(
+ plain[slice_start:slice_end], byteorder="little", signed=False
+ )
+ output.extend(int.to_bytes(res, 8, byteorder="little", signed=False))
iv += 1
encrypted = output[:input_length]
return bytes(encrypted)
@@ -72,24 +78,30 @@ class SpeckEncrypt:
def decrypt(self, iv, encrypted):
return self.encrypt(iv, encrypted)
-class SpeckCMAC:
+class SpeckCMAC:
def __init__(self, key):
self.cipher = SpeckEncrypt(key)
k0 = self.cipher.encrypt_block(0)
- k0 = int.from_bytes(k0.to_bytes(8, byteorder='big'), byteorder='little', signed=False)
+ k0 = int.from_bytes(
+ k0.to_bytes(8, byteorder="big"), byteorder="little", signed=False
+ )
- k1 = (k0 << 1) & 0XFFFFFFFFFFFFFFFF
- if (k0 >> 63 != 0):
+ k1 = (k0 << 1) & 0xFFFFFFFFFFFFFFFF
+ if k0 >> 63 != 0:
k1 ^= 0x1B
- k2 = (k1 << 1) & 0XFFFFFFFFFFFFFFFF
- if (k1 >> 63 != 0):
+ k2 = (k1 << 1) & 0xFFFFFFFFFFFFFFFF
+ if k1 >> 63 != 0:
k2 ^= 0x1B
- k1 = int.from_bytes(k1.to_bytes(8, byteorder='big'), byteorder='little', signed=False)
- k2 = int.from_bytes(k2.to_bytes(8, byteorder='big'), byteorder='little', signed=False)
+ k1 = int.from_bytes(
+ k1.to_bytes(8, byteorder="big"), byteorder="little", signed=False
+ )
+ k2 = int.from_bytes(
+ k2.to_bytes(8, byteorder="big"), byteorder="little", signed=False
+ )
self.k1 = k1
self.k2 = k2
@@ -98,22 +110,33 @@ class SpeckCMAC:
i = 0
data_len = len(data)
- while (i < data_len):
+ while i < data_len:
data_left = data_len - i
- if (data_left == 8):
- block = int.from_bytes(data[i:i+8], 'little') ^ self.k1
- elif (data_left < 8):
- block = int.from_bytes(data[i:i+data_left] + b'\x80' + b'\x00'*(7-data_left), 'little') ^ self.k2
+ slice_start = i
+ slice_end = slice_start + 8
+ if data_left == 8:
+ block = int.from_bytes(data[slice_start:slice_end], "little") ^ self.k1
+ elif data_left < 8:
+ slice_end = i + data_left
+ block = (
+ int.from_bytes(
+ data[slice_start:slice_end]
+ + b"\x80"
+ + b"\x00" * (7 - data_left),
+ "little",
+ )
+ ^ self.k2
+ )
else:
- block = int.from_bytes(data[i:i+8], 'little')
+ block = int.from_bytes(data[slice_start:slice_end], "little")
c = self.cipher.encrypt_block(c ^ block)
i += 8
return c
def derive(self, label, context):
- data = label + b'\x00' + context + b'\x80\x00'
- d1 = self.sign(b'\x01' + data)
- d2 = self.sign(b'\x02' + data) << 64
+ data = label + b"\x00" + context + b"\x80\x00"
+ d1 = self.sign(b"\x01" + data)
+ d2 = self.sign(b"\x02" + data) << 64
return d1 | d2