def ccm.mac

bend-osdev-cipher-modes@0.1.0.0 · ccm.bend:51

import Base
import bend-osdev-bytes@0.1.0.0/bytes.bend as B
import bend-osdev-cipher-modes@0.1.0.0/cipher_modes.bend as M

51# the CBC-MAC of B_0, the encoded a and the padded p
52def ccm.mac(~K: Data, ~enc: K -> M.CmBlock -> M.CmBlock, +k: K, +m: Nat, +l: Nat, +nonce: List<&2, U32>, +a: List<&2, U32>, +p: List<&2, U32>) -> M.CmBlock:
53  +adata = B.len(a)
54  +flags = U32.from_nat(Nat.add(Nat.add(Nat.mul(64n, Nat.min(adata, 1n)), Nat.mul(8n, Nat.div(Nat.sub(m, 2n), 2n))), Nat.sub(l, 1n)))
55  +input = B.append(Con{flags, B.append(nonce, ccm.be(l, U32.from_nat(B.len(p))))}, B.append(ccm.aad.pick(Nat.is_eq(adata, 0n), a), ccm.pad(p)))
56  ccm.cbcmac(~K, ~enc, k, M.cm.split.blocks(M.cm.split(input)), M.CmBlock.zero())