def ccmp.ctrb2

bend-osdev-cipher-modes@0.1.0.0 · PROOF.bend:1773

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/ccm.bend as CC

1773# CTR twice is the identity on blocks
1774def ccmp.ctrb2(~K: Data, ~enc: K -> M.CmBlock -> M.CmBlock, +k: K, bs: List<&2, M.CmBlock>, +a0: M.CmBlock, +i: U32) -> {CC.ccm.ctrb(~K, ~enc, k, CC.ccm.ctrb(~K, ~enc, k, bs, a0, i), a0, i) == bs : List<&2, M.CmBlock>}:
1775  match bs:
1776    case Nil{}:
1777      {==}
1778    case Con{+b, +rest}:
1779      %Equal.sym(M.CmBlock, M.CmBlock.xor(M.CmBlock.xor(b, enc(k, CC.ccm.ai(a0, i))), enc(k, CC.ccm.ai(a0, i))), b, bx.rblock(b, enc(k, CC.ccm.ai(a0, i)))) : {Con{_, CC.ccm.ctrb(~K, ~enc, k, CC.ccm.ctrb(~K, ~enc, k, rest, a0, U32.add(i, 1)), a0, U32.add(i, 1))} == Con{b, rest} : List<&2, M.CmBlock>}
1780      %Equal.sym(List<&2, M.CmBlock>, CC.ccm.ctrb(~K, ~enc, k, CC.ccm.ctrb(~K, ~enc, k, rest, a0, U32.add(i, 1)), a0, U32.add(i, 1)), rest, ccmp.ctrb2(~K, ~enc, k, rest, a0, U32.add(i, 1))) : {Con{b, _} == Con{b, rest} : List<&2, M.CmBlock>}
1781      {==}