1 files changed, 178 insertions, 0 deletions
diff --git a/python/lilliput/tbc.py b/python/lilliput/tbc.py
new file mode 100644
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+"""
+    Lilliput TBC
+"""
+from .constants import BLOCK_BYTES, Sbox
+from .multiplications import ALPHAS
+
+
+permutation = [14, 11, 12, 10, 8, 9, 13, 15, 3, 1, 4, 5, 6, 0, 2, 7]
+permutationInv = [13, 9, 14, 8, 10, 11, 12, 15, 4, 5, 3, 1, 2, 6 ,0 ,7]
+
+################################################################################
+
+def BuildTweakey(tweak, key):
+    return tweak+key
+
+#############################
+
+def _lane(TK, j):
+    return TK[j*8:(j+1)*8]
+
+def RoundTweakeySchedule(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 SubTweakeyExtract(tweakey, Ci):
+    RTKi = [0]*8
+
+    for j, byte in enumerate(tweakey):
+        RTKi[j%8] ^= byte
+
+    RTKi[0] ^= Ci
+
+    return RTKi
+
+
+def TweakeyScheduleWhole(tweakey, r):
+    # store main tweakey in TKs[0]
+    # and corresponding round tweakey in RTKs[0]
+    TKs = [tweakey]
+    RTKs = [SubTweakeyExtract(TKs[0], 0)]
+
+    for i in range(1, r):
+        TKs.append(RoundTweakeySchedule(TKs[i-1]))
+        RTKs.append(SubTweakeyExtract(TKs[i], i))
+
+    return RTKs
+
+
+################################################################################
+
+def NonLinearLayer(state, subtweakey):
+
+    variables_xored = [0 for byte in range(0, 8)]
+    for byte in range(0,8):
+        variables_xored[byte] = state[byte] ^ subtweakey[byte]
+
+    variables_sboxed = [0 for byte in range(0, 8)]
+    for byte in range(0, 8):
+        variables_sboxed[byte] = Sbox[variables_xored[byte]]
+
+    state_output = [0 for byte in range(0, BLOCK_BYTES)]
+    for byte in range(0,BLOCK_BYTES):
+        state_output[byte] = state[byte]
+    for byte in range(0, 8):
+        state_output[15 - byte] ^= variables_sboxed[byte]
+
+    return state_output
+
+
+def LinearLayer(state):
+    state_output = [0 for byte in range(0, BLOCK_BYTES)]
+    for byte in range(0, BLOCK_BYTES):
+        state_output[byte] = state[byte]
+
+    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 PermutationLayerEnc(state):
+    state_output = [0 for byte in range(0, BLOCK_BYTES)]
+    for byte in range(0, BLOCK_BYTES):
+        state_output[byte] = state[permutation[byte]]
+
+    return state_output
+
+def PermutationLayerDec(state):
+    state_output = [0 for byte in range(0, BLOCK_BYTES)]
+    for byte in range(0, BLOCK_BYTES):
+        state_output[byte] = state[permutationInv[byte]]
+
+    return state_output
+
+
+def OneRoundEGFNEnc(state, subtweakey):
+    state_non_linear = NonLinearLayer(state, subtweakey)
+    state_linear = LinearLayer(state_non_linear)
+    state_permutation = PermutationLayerEnc(state_linear)
+
+    return state_permutation
+
+def LastRoundEGFN(state, subtweakey):
+    state_non_linear = NonLinearLayer(state, subtweakey)
+    state_linear = LinearLayer(state_non_linear)
+
+    return state_linear
+
+
+def OneRoundEGFNDec(state, subtweakey):
+    state_non_linear = NonLinearLayer(state, subtweakey)
+    state_linear = LinearLayer(state_non_linear)
+    state_permutation = PermutationLayerDec(state_linear)
+
+    return state_permutation
+
+
+def _rounds(key_bytes):
+    rounds = {
+        128: 32,
+        192: 36,
+        256: 42
+    }
+    return rounds[key_bytes*8]
+
+
+################################################################################
+# Lilliput TBC
+
+def encrypt(tweak, key, message):
+    r = _rounds(len(key))
+
+    tweakey = BuildTweakey(tweak, key)
+    RTKs = TweakeyScheduleWhole(tweakey, r)
+
+    state = [0 for byte in range(0, BLOCK_BYTES)]
+    for byte in range(0, BLOCK_BYTES):
+        state[byte] = message[byte]
+
+    for i in range(0, r-1):
+        state_output = OneRoundEGFNEnc(state, RTKs[i])
+
+        for byte in range(0, BLOCK_BYTES):
+            state[byte] = state_output[byte]
+
+    state_output = LastRoundEGFN(state, RTKs[r-1])
+
+    return state_output
+
+
+def decrypt(tweak, key, cipher):
+    r = _rounds(len(key))
+
+    tweakey = BuildTweakey(tweak, key)
+    RTKs = TweakeyScheduleWhole(tweakey, r)
+
+    state = [0 for byte in range(0, BLOCK_BYTES)]
+    for byte in range(0, BLOCK_BYTES):
+        state[byte] = cipher[byte]
+
+    for i in range(0, r-1):
+        state_output = OneRoundEGFNDec(state, RTKs[r-i-1])
+
+        for byte in range(0, BLOCK_BYTES):
+            state[byte] = state_output[byte]
+
+    state_output = LastRoundEGFN(state, RTKs[0])
+
+    return state_output