My own corner of monopam
ocaml-spake2: rewrite README examples to typecheck and seed RNG
[Spake2.finish] returns [(string, string) result] and SPAKE2+ uses
[(string, string, string) result] tuples — both flows used the
[Ok ...] result as bare bytes. Pattern-match each, [assert]
[String.equal] on the derived keys. Re-bind [password] in the
SPAKE2+ block since mdx blocks don't share state across sections.
Initialise [Crypto_rng_unix] at the top of the SPAKE2 block (and add
[nox-crypto-rng.unix] to the mdx libs) so [Spake2.init] doesn't
raise [Crypto_rng: no default generator].
+24
-12
+23
-11
ocaml-spake2/README.md
+23
-11
ocaml-spake2/README.md
···
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### SPAKE2
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```ocaml
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+
let () = Crypto_rng_unix.use_default ()
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+
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let password = "secret"
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-
(* Party A sends msg_a to B, receives msg_b from B *)
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(* Party A sends msg_a to B, receives msg_b from B. *)
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let state_a, msg_a = Spake2.init ~password `A
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-
(* Party B sends msg_b to A, receives msg_a from A *)
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(* Party B sends msg_b to A, receives msg_a from A. *)
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let state_b, msg_b = Spake2.init ~password `B
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-
let key_a = Spake2.finish ~context:"myapp" state_a msg_b
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let key_b = Spake2.finish ~context:"myapp" state_b msg_a
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-
(* key_a = key_b *)
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let () =
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match
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( Spake2.finish ~context:"myapp" state_a msg_b,
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Spake2.finish ~context:"myapp" state_b msg_a )
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with
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| Ok key_a, Ok key_b -> assert (String.equal key_a key_b)
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| _ -> failwith "finish failed"
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```
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### SPAKE2+
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```ocaml
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-
(* Setup: derive verifier data from password *)
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let password = "secret"
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+
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(* Setup: derive verifier data from password. *)
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let salt = Spake2.Plus.generate_salt ()
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let iterations = 1000
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let w0, w1 = Spake2.Plus.derive_w ~password ~salt ~iterations
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(* Server stores: w0, l, salt, iterations (NOT the password or w1) *)
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let l = Spake2.Plus.compute_l ~w1
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(* Protocol run: exchange pa and pb between prover and verifier *)
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(* Protocol run: exchange pa and pb between prover and verifier. *)
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let context = "myapp"
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let prover_state, pa = Spake2.Plus.prover_init ~w0 ~w1 ~context
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let verifier_state, pb = Spake2.Plus.verifier_init ~w0 ~l ~context
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-
(* ke_prover = ke_verifier; ca and cb are exchanged for confirmation *)
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let Ok (ke_prover, ca, _) = Spake2.Plus.prover_finish prover_state pb
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-
let Ok (ke_verifier, cb, _) = Spake2.Plus.verifier_finish verifier_state pa
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+
let () =
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match
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( Spake2.Plus.prover_finish prover_state pb,
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Spake2.Plus.verifier_finish verifier_state pa )
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with
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| Ok (ke_prover, _ca, _), Ok (ke_verifier, _cb, _) ->
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assert (String.equal ke_prover ke_verifier)
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| _ -> failwith "spake2+ exchange failed"
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```
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## API