law cbc_blocks_round_trip

bend-osdev-cipher-modes@0.1.0.0 · LAWS.bend:19

import Base
import bend-osdev-cipher-modes@0.1.0.0/cipher_modes.bend as M
import bend-osdev-cipher-modes@0.1.0.0/cbc.bend as C

19# CBC on blocks: decryption undoes encryption, for every key, IV and message
20law cbc_blocks_round_trip:
21  for ~K: Data
22  for ~enc: K -> M.CmBlock -> M.CmBlock
23  for ~dec: K -> M.CmBlock -> M.CmBlock
24  for ~inv: @k: K -> @b: M.CmBlock -> {dec(k, enc(k, b)) == b : M.CmBlock}
25  for +k: K
26  for iv: M.CmBlock
27  for bs: List<&2, M.CmBlock>
28  {C.Cbc.decrypt_blocks(~K, ~dec, k, iv, C.Cbc.encrypt_blocks(~K, ~enc, k, iv, bs)) == bs : List<&2, M.CmBlock>}