1 files changed, 156 insertions, 0 deletions
diff --git a/src/add_python/lilliput/tbc.py b/src/add_python/lilliput/tbc.py
new file mode 100644
index 0000000..0772853
--- /dev/null
+++ b/src/add_python/lilliput/tbc.py
@@ -0,0 +1,156 @@
+# Implementation of the Lilliput-AE tweakable block cipher.
+#
+# Authors, hereby denoted as "the implementer":
+#     Kévin Le Gouguec,
+#     Léo Reynaud
+#     2019.
+#
+# For more information, feedback or questions, refer to our website:
+# https://paclido.fr/lilliput-ae
+#
+# To the extent possible under law, the implementer has waived all copyright
+# and related or neighboring rights to the source code in this file.
+# http://creativecommons.org/publicdomain/zero/1.0/
+
+"""Lilliput-TBC tweakable block cipher.
+
+This module provides functions to encrypt and decrypt blocks of 128 bits.
+"""
+
+from .constants import BLOCK_BYTES, SBOX
+from .helpers import xor
+from .multiplications import ALPHAS
+
+
+_PERMUTATION = [14, 11, 12, 10, 8, 9, 13, 15, 3, 1, 4, 5, 6, 0, 2, 7]
+_PERMUTATION_INV = [13, 9, 14, 8, 10, 11, 12, 15, 4, 5, 3, 1, 2, 6 ,0 ,7]
+
+
+_ROUNDS = {
+    128: 32,
+    192: 36,
+    256: 42
+}
+
+
+def _build_tweakey(tweak, key):
+    return tweak+key
+
+
+def _lane(TK, j):
+    return TK[j*8:(j+1)*8]
+
+
+def _round_tweakey_schedule(tweakey):
+    p = len(tweakey)//8
+
+    multiplied_lanes = (
+        ALPHAS[j](_lane(tweakey, j)) for j in range(p)
+    )
+
+    return [byte for lane in multiplied_lanes for byte in lane]
+
+
+def _subtweakey_extract(tweakey, Ci):
+    RTKi = [0]*8
+
+    for j, byte in enumerate(tweakey):
+        RTKi[j%8] ^= byte
+
+    RTKi[0] ^= Ci
+
+    return RTKi
+
+
+def _tweakey_schedule_whole(tweakey, r):
+    TKs = [tweakey]
+    RTKs = [_subtweakey_extract(TKs[0], 0)]
+
+    for i in range(1, r):
+        TKs.append(_round_tweakey_schedule(TKs[i-1]))
+        RTKs.append(_subtweakey_extract(TKs[i], i))
+
+    return RTKs
+
+
+def _non_linear_layer(state, subtweakey):
+    variables_xored = xor(state, subtweakey)
+
+    variables_sboxed = [
+        SBOX[variables_xored[i]] for i in range(8)
+    ]
+
+    state_output = state
+    for i in range(8):
+        state_output[15-i] ^= variables_sboxed[i]
+
+    return state_output
+
+
+def _linear_layer(state):
+    state_output = state
+
+    for byte in range(1, 8):
+        state_output[15] ^= state[byte]
+
+    for byte in range(9, 15):
+        state_output[byte] ^= state[7]
+
+    return state_output
+
+
+def _permutation_layer(state, p):
+    return [
+        state[p[i]] for i in range(BLOCK_BYTES)
+    ]
+
+
+def _one_round_egfn_enc(state, subtweakey):
+    state_non_linear = _non_linear_layer(state, subtweakey)
+    state_linear = _linear_layer(state_non_linear)
+    state_permutation = _permutation_layer(state_linear, _PERMUTATION)
+
+    return state_permutation
+
+
+def _last_round_egfn(state, subtweakey):
+    state_non_linear = _non_linear_layer(state, subtweakey)
+    state_linear = _linear_layer(state_non_linear)
+
+    return state_linear
+
+
+def _one_round_egfn_dec(state, subtweakey):
+    state_non_linear = _non_linear_layer(state, subtweakey)
+    state_linear = _linear_layer(state_non_linear)
+    state_permutation = _permutation_layer(state_linear, _PERMUTATION_INV)
+
+    return state_permutation
+
+
+def encrypt(tweak, key, message):
+    r = _ROUNDS[8*len(key)]
+
+    tweakey = _build_tweakey(tweak, key)
+    RTKs = _tweakey_schedule_whole(tweakey, r)
+
+    state = message
+
+    for i in range(r-1):
+        state = _one_round_egfn_enc(state, RTKs[i])
+
+    return _last_round_egfn(state, RTKs[r-1])
+
+
+def decrypt(tweak, key, cipher):
+    r = _ROUNDS[8*len(key)]
+
+    tweakey = _build_tweakey(tweak, key)
+    RTKs = _tweakey_schedule_whole(tweakey, r)
+
+    state = cipher
+
+    for i in range(r-1):
+        state = _one_round_egfn_dec(state, RTKs[r-i-1])
+
+    return _last_round_egfn(state, RTKs[0])