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annotate code with common constructions
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@let-def
let-def committed Apr 22, 2020
1 parent 661ad4b commit 664ea3d
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10 changes: 5 additions & 5 deletions deriv.js
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95 changes: 52 additions & 43 deletions deriv.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,9 @@ let array_copy = Array.copy
!acc
*)

let pass_1_secret_1 = [|
(* Pass 1: (almost certainly...) sha256 *)

let sha256_constants: int array = [|
0x428A2F98; 0x71374491; 0xB5C0FBCF; 0xE9B5DBA5;
0x3956C25B; 0x59F111F1; 0x923F82A4; 0xAB1C5ED5;
0xD807AA98; 0x12835B01; 0x243185BE; 0x550C7DC3;
Expand All @@ -75,12 +77,13 @@ let pass_1_secret_1 = [|
0x90BEFFFA; 0xA4506CEB; 0xBEF9A3F7; 0xC67178F2;
|]

let pass_1_secret_2 = [|
let sha256_iv: int array = [|
0x6A09E667; 0xBB67AE85; 0x3C6EF372; 0xA54FF53A;
0x510E527F; 0x9B05688C; 0x1F83D9AB; 0x5BE0CD19;
|]

let pass_1 key =
(* Specialised for 10 bytes key *)
let sha256 (key: int array): int array =
let obuf = Array.make 64 0 in
for i = 0 to 9 do set_uint8 obuf i (key.(i)); done;
set_uint8 obuf 10 0x80;
Expand All @@ -103,14 +106,14 @@ let pass_1 key =
(tmp.(i - 0x07) + (t0_1 lxor t0_2 lxor t0_3) +
tmp.(i - 0x10) + (td_1 lxor td_2 lxor td_3))
done;
let sbuf = array_copy pass_1_secret_2 in
let sbuf = array_copy sha256_iv in
for i = 0 to 63 do
let s6 = sbuf.(6) in
let s5 = sbuf.(5) in
let s4 = sbuf.(4) in
let tmp =
int32 @@
pass_1_secret_1.(i) + tmp.(i) + sbuf.(7) +
sha256_constants.(i) + tmp.(i) + sbuf.(7) +
((lnot s4 land s6) lxor (s5 land s4)) +
(slr s4 0x15 0x0b lxor slr s4 0x07 0x19 lxor slr s4 0x1a 0x06)
in
Expand All @@ -125,11 +128,13 @@ let pass_1 key =
done;
let result = Array.make 32 0 in
for i = 0 to 7 do
set_int32_be result (i * 4) (sbuf.(i) + pass_1_secret_2.(i))
set_int32_be result (i * 4) (sbuf.(i) + sha256_iv.(i))
done;
result

let pass_2_permutation = [|
(* Pass 2: AES-like, probably with custom sauce? *)

let rijndael_sbox: int array = [|
0x63;0x7C;0x77;0x7B;0xF2;0x6B;0x6F;0xC5;0x30;0x01;0x67;0x2B;0xFE;0xD7;0xAB;0x76;
0xCA;0x82;0xC9;0x7D;0xFA;0x59;0x47;0xF0;0xAD;0xD4;0xA2;0xAF;0x9C;0xA4;0x72;0xC0;
0xB7;0xFD;0x93;0x26;0x36;0x3F;0xF7;0xCC;0x34;0xA5;0xE5;0xF1;0x71;0xD8;0x31;0x15;
Expand All @@ -148,16 +153,16 @@ let pass_2_permutation = [|
0x8C;0xA1;0x89;0x0D;0xBF;0xE6;0x42;0x68;0x41;0x99;0x2D;0x0F;0xB0;0x54;0xBB;0x16;
|]

let pass_2_secret =
let pass_2_secret: int array =
[| 0x8D;0x01;0x02;0x04;0x08;0x10;0x20;0x40;
0x80;0x1B;0x36;0x6C;0xD8;0xAB;0x4D;0x9A |]

let pass_2_1 input =
let pass_2_1 (input: int array): int array =
let len = Array.length input in
let idx = input.(9) land 0xf in
array_init 16 (fun i -> input.((mul i (idx * 2 + 1)) mod len))

let pass_2_2 input =
let pass_2_2 (input: int array): int array =
array_init 16 (fun idx ->
let i = idx lsr 2 and j = idx land 3 in
let acc = ref 0 in
Expand All @@ -168,26 +173,26 @@ let pass_2_2 input =
!acc land 0xFF
)

let pass_2_switch_0 input =
let pass_2_switch_0 (input: int array): int array =
array_init 16 (fun idx ->
let i = 3 - idx lsr 2 and j = idx land 3 in
input.(j * 4 + i)
)

let pass_2_switch_1 input =
let pass_2_switch_1 (input: int array): int array =
array_init 16 (fun idx ->
let i = idx lsr 2 and j = 3 - idx land 3 in
input.(j * 4 + i)
)

let pass_2_switch_2 input =
let pass_2_switch_2 (input: int array): int array =
array_init 16 (fun idx ->
let i = idx lsr 2 and j = idx land 3 in
let c = input.((j + i) land 3 + i * 4) in
((c + i) land 0xFF)
)

let pass_2_switch_3 input =
let pass_2_switch_3 (input: int array): int array =
let acc1 = ref 0 and acc2 = ref 0 in
for i = 0 to 3 do
acc1 := !acc1 lxor input.(i * 5);
Expand All @@ -197,13 +202,13 @@ let pass_2_switch_3 input =
array_init 16
(fun i -> input.(i) lxor (if i land 1 = 0 then acc1 else acc2))

let pass_2_switch_4 input =
let pass_2_switch_4 (input: int array): int array =
array_init 16 (fun i ->
let c1 = input.(i) and c2 = input.((i+1) land 0xF) in
c1 lxor (if c2 < c1 then c2 else 0xFF)
)

let pass_2_switch_5 input =
let pass_2_switch_5 (input: int array): int array =
let buf = Array.make 16 0 in
for i = 0 to 3 do
let acc = ref 0 in
Expand All @@ -215,13 +220,15 @@ let pass_2_switch_5 input =
done;
buf

let pass_2_3 scratch buf offset =
let pass_2_3 (scratch: int array) (buf: int array) (offset: int): unit =
let o = (offset land 0xFF) lsl 4 in
for i = 0 to 15 do
set_uint8 buf i (get_uint8 buf i lxor get_uint8 scratch (o + i)) done
set_uint8 buf i
(get_uint8 buf i lxor get_uint8 scratch (o + i))
done

let pass_2_permute buf =
for i = 0 to 15 do set_uint8 buf i pass_2_permutation.(get_uint8 buf i) done;
let pass_2_permute (buf: int array): unit =
for i = 0 to 15 do set_uint8 buf i rijndael_sbox.(get_uint8 buf i) done;
let b01 = get_uint8 buf 0x01 in
set_uint8 buf 0x01 (get_uint8 buf 0x05);
set_uint8 buf 0x05 (get_uint8 buf 0x09);
Expand All @@ -241,7 +248,7 @@ let pass_2_permute buf =
set_uint8 buf 0x07 b03;
set_uint8 buf 0x0b b07

let pass_2_4 scratch input =
let pass_2_4 (scratch: int array) (input: int array): int array =
let buf = array_copy input in
pass_2_3 scratch buf 0;
for i = 1 to 9 do
Expand Down Expand Up @@ -272,7 +279,7 @@ let pass_2_4 scratch input =
pass_2_3 scratch buf 10;
buf

let pass_2 input =
let pass_2 (input: int array): int array =
let scram_1 = pass_2_1 input in
let scram_2 =
let scram_2 = pass_2_2 input in
Expand All @@ -294,10 +301,10 @@ let pass_2 input =
let b3 = get_uint8 scratch (i - 1) in
let b0, b1, b2, b3 =
if (i land 12) = 0 then (
get_uint8 pass_2_permutation b1 lxor get_uint8 pass_2_secret (i / 16),
get_uint8 pass_2_permutation b2,
get_uint8 pass_2_permutation b3,
get_uint8 pass_2_permutation b0
get_uint8 rijndael_sbox b1 lxor get_uint8 pass_2_secret (i / 16),
get_uint8 rijndael_sbox b2,
get_uint8 rijndael_sbox b3,
get_uint8 rijndael_sbox b0
) else
(b0, b1, b2, b3)
in
Expand All @@ -308,11 +315,13 @@ let pass_2 input =
done;
pass_2_4 scratch scram_1

let pass_3_secret_hi = 0xC96C5795
(* Pass 3: (almost certainly...) CRC64 *)

let pass_3_secret_lo = 0xD7870F42
let crc64_hi: int = 0xC96C5795

let pass_3_derived =
let crc64_lo: int = 0xD7870F42

let crc64_table: int array =
let arr = Array.make 512 0 in
for i = 0 to 255 do
let acc1 = ref 0 in
Expand All @@ -324,50 +333,50 @@ let pass_3_derived =
acc1 := acc1';
acc2 := acc2';
) else (
acc1 := acc1' lxor pass_3_secret_hi;
acc2 := acc2' lxor pass_3_secret_lo;
acc1 := acc1' lxor crc64_hi;
acc2 := acc2' lxor crc64_lo;
)
done;
arr.(2 * i + 0) <- !acc1;
arr.(2 * i + 1) <- !acc2;
done;
arr

let pass_3 input =
let crc64 (input: int array): int array =
let acc1 = ref 0 in
let acc2 = ref 0 in
for i = 0 to 15 do
let c = input.(i) in
let acc1' = (!acc1 lsr 8) in
let acc2' = (!acc2 lsr 8) lor ((!acc1 land 0xFF) lsl 24) in
let ofs = (!acc2 land 0xFF) lxor c in
acc1 := acc1' lxor pass_3_derived.(ofs * 2 + 0);
acc2 := acc2' lxor pass_3_derived.(ofs * 2 + 1);
acc1 := acc1' lxor crc64_table.(ofs * 2 + 0);
acc2 := acc2' lxor crc64_table.(ofs * 2 + 1);
done;
let acc1 = !acc1 and acc2 = !acc2 in
let result = Array.make 8 0 in
set_int32_be result 0 acc1;
set_int32_be result 4 acc2;
result

let raw_unlock key =
pass_3 (pass_2 (pass_1 key))
let raw_unlock (key: int array): int array =
crc64 (pass_2 (sha256 key))

let to_hex c =
let to_hex (c: int): char =
Char.chr (if c <= 9 then Char.code '0' + c else Char.code 'a' + c - 10)

open Js_of_ocaml

let unlock str =
let unlock (str: string): string =
let array str = Array.init (String.length str) (fun i -> Char.code str.[i]) in
let code = str |> Js.to_string |> array |> raw_unlock in
let code = raw_unlock (array str) in
let bytes = Bytes.make 16 '\000' in
for i = 0 to 7 do
let c = code.(i) in
let c0 = c lsr 4 and c1 = c land 0xF in
Bytes.set bytes (2 * i + 0) (to_hex c0);
Bytes.set bytes (2 * i + 1) (to_hex c1);
done;
Js.string (Bytes.to_string bytes)
Bytes.to_string bytes

let () = Js.export "unlock" unlock
let () =
let open Js_of_ocaml in
Js.export "unlock" (fun key -> Js.string (unlock (Js.to_string key)))

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