def ccm.dbody

bend-osdev-cipher-modes@0.1.0.0 · ccm.bend:151

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

151# the plaintext, if the tag (compared with no early exit) matches
152def ccm.dbody(~K: Data, ~enc: K -> M.CmBlock -> M.CmBlock, +k: K, +m: Nat, +nv: List<&2, U32>, +av: List<&2, U32>, +cv: List<&2, U32>) -> Result<&2, &2, M.CmError, B.Octets>:
153  +body = Nat.sub(B.len(cv), m)
154  +l = Nat.sub(15n, B.len(nv))
155  +a0 = ccm.a0(l, nv)
156  +pv = ccm.xcrypt(~K, ~enc, k, a0, M.cm.split(B.take(body, cv)))
157  ccm.open(M.cm.ct_eq(M.cm.xor_bytes(B.drop(body, cv), M.cm.bytes_of(enc(k, a0))), ccm.tag(~K, ~enc, k, m, l, nv, av, pv)), pv)