53 lines
1.6 KiB
OCaml
53 lines
1.6 KiB
OCaml
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module Make (H : Digestif.S) = struct
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type g =
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{ mutable k : string
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; mutable v : string
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; mutable seeded : bool
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}
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let block = H.digest_size
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let (bx00, bx01) = "\x00", "\x01"
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let k0 = String.make H.digest_size '\x00'
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and v0 = String.make H.digest_size '\x01'
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let create ?time:_ () = { k = k0 ; v = v0 ; seeded = false }
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let seeded ~g = g.seeded
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let reseed ~g buf =
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let (k, v) = (g.k, g.v) in
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let k = H.hmac_string ~key:k @@ String.concat "" [v; bx00; buf] |> H.to_raw_string in
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let v = H.hmac_string ~key:k v |> H.to_raw_string in
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let k = H.hmac_string ~key:k @@ String.concat "" [v; bx01; buf] |> H.to_raw_string in
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let v = H.hmac_string ~key:k v |> H.to_raw_string in
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g.k <- k ; g.v <- v ; g.seeded <- true
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let generate_into ~g buf ~off len =
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if not g.seeded then raise Rng.Unseeded_generator ;
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let rec go off k v = function
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| 0 -> v
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| 1 ->
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let v = H.hmac_string ~key:k v |> H.to_raw_string in
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let len =
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let rem = len mod H.digest_size in
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if rem = 0 then H.digest_size else rem
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in
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Bytes.unsafe_blit_string v 0 buf off len;
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v
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| i ->
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let v = H.hmac_string ~key:k v |> H.to_raw_string in
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Bytes.unsafe_blit_string v 0 buf off H.digest_size;
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go (off + H.digest_size) k v (pred i)
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in
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let v = go off g.k g.v Mirage_crypto.Uncommon.(len // H.digest_size) in
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g.k <- H.hmac_string ~key:g.k (v ^ bx00) |> H.to_raw_string;
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g.v <- H.hmac_string ~key:g.k v |> H.to_raw_string
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(* XXX *)
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let accumulate ~g:_ = invalid_arg "Implement Hmac_drbg.accumulate..."
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let pools = 0
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end
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