def cr.kb.ctr

bend-osdev-crypto@0.1.0.0 · kbkdf.bend:47

import Base
import bend-osdev-bytes@0.1.0.0/bytes.bend as B

47# n more bytes in counter mode: the rest of the current block cur, then
48# PRF(K_IN, [i + 1]_2 || fixed), ...
49def cr.kb.ctr(~K: Data, ~compute: K -> B.Octets -> B.Octets, n: Nat, cur: List<&2, U32>, +k: K, +rlen: Nat, +fixed: B.Octets, +i: U32) -> List<&2, U32>:
50  match n:
51    case 0n:
52      Nil{}
53    case 1n+p:
54      match cur:
55        case Con{h, t}:
56          Con{h, cr.kb.ctr(~K, ~compute, p, t, k, rlen, fixed, i)}
57        case Nil{}:
58          +blk = B.Octets.to_list(compute(k, B.Octets.append(CrKbkdf.counter(rlen, U32.add(i, 1)), fixed)))
59          Con{cr.kb.head(blk), cr.kb.ctr(~K, ~compute, p, cr.kb.tail(blk), k, rlen, fixed, U32.add(i, 1))}