SPAKE2/SPAKE2+ password-authenticated key exchange for OCaml
ocaml-linkedin: apply dune fmt
Pure formatting changes from `dune fmt`: doc comment placement moves
from above the binding to below it for `type`s, multi-line `match`
expressions collapse onto one line where they fit, and infix operator
applications pick up spaces (`Soup.($?)` -> `Soup.( $? )`). No
semantic changes.
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README.md
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## Installation
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Install with opam:
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```sh
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$ opam install spake2
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```
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opam install spake2
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If opam cannot find the package, it may not yet be released in the public
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`opam-repository`. Add the overlay repository, then install it:
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```sh
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$ opam repo add samoht https://tangled.org/gazagnaire.org/opam-overlay.git
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$ opam update
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$ opam install spake2
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```
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## Usage
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### SPAKE2
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```ocaml
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let password = "secret" in
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let password = "secret"
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(* Party A *)
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let state_a, msg_a = Spake2.init ~password `A in
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(* send msg_a to B, receive msg_b from B *)
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let key_a = Spake2.finish ~context:"myapp" state_a msg_b in
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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 *)
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let state_b, msg_b = Spake2.init ~password `B in
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(* send msg_b to A, receive msg_a from A *)
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let key_b = Spake2.finish ~context:"myapp" state_b msg_a in
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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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```
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···
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```ocaml
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(* Setup: derive verifier data from password *)
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let salt = Spake2.Plus.generate_salt () in
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let iterations = 1000 in
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let w0, w1 = Spake2.Plus.derive_w ~password ~salt ~iterations in
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let l = Spake2.Plus.compute_l ~w1 in
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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 *)
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let context = "myapp" in
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let prover_state, pa = Spake2.Plus.prover_init ~w0 ~w1 ~context in
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let verifier_state, pb = Spake2.Plus.verifier_init ~w0 ~l ~context in
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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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(* Exchange pa and pb *)
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let Ok (ke_prover, ca, _) = Spake2.Plus.prover_finish prover_state pb in
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let Ok (ke_verifier, cb, _) = Spake2.Plus.verifier_finish verifier_state pa in
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(* ke_prover = ke_verifier *)
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(* ca and cb can be exchanged for key confirmation *)
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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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```
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## API
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