diff options
Diffstat (limited to 'python/lilliput_ae_2.py')
| -rw-r--r-- | python/lilliput_ae_2.py | 127 |
1 files changed, 0 insertions, 127 deletions
diff --git a/python/lilliput_ae_2.py b/python/lilliput_ae_2.py deleted file mode 100644 index 3c0aa2a..0000000 --- a/python/lilliput_ae_2.py +++ /dev/null @@ -1,127 +0,0 @@ -""" - SCT 2 for lilliput ae 2 -""" - -from constants import BLOCK_BYTES -from helpers import ( - ArrayToBlockbytesMatrix, - BlockbytesMatrixToBytes, - BuildAuth, - Padding10LSB, - TagValidationError, - XorState -) -import tbc - - -TWEAK_BITS = 128 -TWEAK_BYTES = TWEAK_BITS//8 - - -def TweakTag(j, padded): - tweak = [0 for byte in range(0, TWEAK_BYTES)] - - tweak[TWEAK_BYTES - 1] |= ((j >> 120) & 0xf) - for byte in range(TWEAK_BYTES - 2, -1, -1): - tweak[byte] = (j >> (8 * byte)) & 0xff - - if padded: - tweak[TWEAK_BYTES - 1] |= 0x40 - - return tweak - - -def TweakTagEnd(N): - tweak = [0 for byte in range(0, TWEAK_BYTES)] - - for byte in range(0, TWEAK_BYTES - 1): - tweak[byte] = N[byte] - tweak[TWEAK_BYTES - 1] = 0x10 - - return tweak - - -def AddTagJ(tag, j): - array_j = [0 for byte in range(0, TWEAK_BYTES)] - for byte in range(0, TWEAK_BYTES): - array_j[byte] = (j >> (byte * 8)) - - xorr = XorState(tag, array_j) - - xorr[TWEAK_BYTES - 1] |= 0x80 - - return xorr - - -def MesssageAuthTag(M, N, Auth, key): - l = len(M)//BLOCK_BYTES - need_padding = len(M)%BLOCK_BYTES > 0 - - tag = list(Auth) - M = ArrayToBlockbytesMatrix(M) - - for j in range(0, l): - tweak = TweakTag(j, False) - encryption = tbc.encrypt(tweak, key, M[j]) - tag = XorState(tag, encryption) - - if need_padding: - tweak = TweakTag(l, True) - m_padded = Padding10LSB(M[l]) - encryption = tbc.encrypt(tweak, key, m_padded) - tag = XorState(tag, encryption) - - tweak = TweakTagEnd(N) - encryption = tbc.encrypt(tweak, key, tag) - tag = encryption - - return tag - - -def MessageEncryption(M, N, tag, key): - l = len(M)//BLOCK_BYTES - need_padding = len(M)%BLOCK_BYTES > 0 - - M = ArrayToBlockbytesMatrix(M) - C = [] - - for j in range(0, l): - tweak = AddTagJ(tag, j) - padded_nonce = list(N) + [0x00] - encryption = tbc.encrypt(tweak, key, padded_nonce) - C.append(XorState(M[j], encryption)) - - if need_padding: - tweak = AddTagJ(tag, l) - padded_nonce = list(N) + [0x00] - encryption = tbc.encrypt(tweak, key, padded_nonce) - C.append(XorState(M[l], encryption)) - - return C - - -################################################################################ -def encrypt(A, M, N, key): - K = list(key) - - Auth = BuildAuth(TWEAK_BITS, A, K) - tag = MesssageAuthTag(M, N, Auth, K) - C = MessageEncryption(M, N, tag, K) - - return BlockbytesMatrixToBytes(C), bytes(tag) - - -def decrypt(A, C, N, tag, key): - K = list(key) - tag = list(tag) - - M = BlockbytesMatrixToBytes( - MessageEncryption(C, N, tag, K) - ) - Auth = BuildAuth(TWEAK_BITS, A, K) - tag2 = MesssageAuthTag(M, N, Auth, K) - - if tag != tag2: - raise TagValidationError(tag, tag2) - - return M |
