swrup/mte
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

use Eqaf

Browse source
This commit is contained in:
swrup 2026-02-24 22:06:53 +01:00
parent d870eab54e
commit c26f3111c3
3 changed files with 15 additions and 29 deletions
Download patch file Download diff file Expand all files Collapse all files

32
src/fdh_rsa.ml
View file

@ -1,9 +1,6 @@
(* WIP fdh-rsa (* WIP fdh-rsa
full-domain-hash RSA full-domain-hash RSA
based on libgnunetutil crypto_rsa.c based on libgnunetutil crypto_rsa.c *)
good explanation of taler crypto:
https://www.taler.net/papers/cs-thesis.pdf *)
module Z_extra = Mirage_crypto_pk.Z_extra module Z_extra = Mirage_crypto_pk.Z_extra
open Crypto open Crypto
@ -56,19 +53,14 @@ let rsa_blinding_key_derive (pub : RsaPublicKey.t) bks =
let r = Kdf.kdf_mod_n ~n:pub.n ~xts ~ikm:bks ~ctx in let r = Kdf.kdf_mod_n ~n:pub.n ~xts ~ikm:bks ~ctx in
gcd_validate r pub.n; r gcd_validate r pub.n; r
let rsa_blind pub ~bks msg = let blind_msg pub ~bks msg =
let data = rsa_full_domain_hash pub msg in let data = rsa_full_domain_hash pub msg in
let bkey = rsa_blinding_key_derive pub bks in let bkey = rsa_blinding_key_derive pub bks in
(* can we just use [powm] here instead? *)
let r_e = Z.powm_sec bkey pub.e pub.n in let r_e = Z.powm_sec bkey pub.e pub.n in
let data_r_e = Z.rem (Z.mul data r_e) pub.n in let data_r_e = Z.rem (Z.mul data r_e) pub.n in
Z_extra.to_octets_be data_r_e Z_extra.to_octets_be data_r_e
(* decrypt <=> sign *) let unblind_sig pub ~bks bsig =
let rsa_sign_blinded priv bmsg =
Mirage_crypto_pk.Rsa.decrypt ~crt_hardening:true ~key:priv bmsg
let rsa_unblind pub ~bks bsig =
let data = Z_extra.of_octets_be bsig in let data = Z_extra.of_octets_be bsig in
let bkey = rsa_blinding_key_derive pub bks in let bkey = rsa_blinding_key_derive pub bks in
let r_inv = let r_inv =
@ -80,19 +72,13 @@ let rsa_unblind pub ~bks bsig =
let data = Z.rem (Z.mul data r_inv) pub.n in let data = Z.rem (Z.mul data r_inv) pub.n in
Z_extra.to_octets_be data Z_extra.to_octets_be data
let sign ~priv ~pub ~bks ~msg = (* decrypt <=> sign *)
let bmsg = rsa_blind pub ~bks msg in let sign ~key bmsg = Mirage_crypto_pk.Rsa.decrypt ~crt_hardening:true ~key bmsg
let bsig = rsa_sign_blinded priv bmsg in
let sig_ = rsa_unblind pub ~bks bsig in
sig_
(* TODO fdh-rsa let verify ~key s ~msg =
look into mirage-crypto for this let msg_fdh = rsa_full_domain_hash key msg in
at least use Eqaf for constant time string compare *)
let verify pub ~msg ~sig_ =
let msg_fdh = rsa_full_domain_hash pub msg in
let s1 = Z_extra.to_octets_be msg_fdh in let s1 = Z_extra.to_octets_be msg_fdh in
let s2 = Mirage_crypto_pk.Rsa.encrypt ~key:pub sig_ in let s2 = Mirage_crypto_pk.Rsa.encrypt ~key s in
match String.equal s1 s2 with match Eqaf.equal s1 s2 with
| false -> Fmt.error "RSA signature verification failed" | false -> Fmt.error "RSA signature verification failed"
| true -> Ok () | true -> Ok ()

4
src/secmod_rsa.ml
View file

@ -259,9 +259,7 @@ module Make () = struct
let sign h_pub msg = let sign h_pub msg =
let+ k = find h_pub in let+ k = find h_pub in
(* TODO fdh-rsa *) let data = Fdh_rsa.sign ~key:k.priv msg in
let bks = "deadbeaf" in
let data = Fdh_rsa.sign ~priv:k.priv ~pub:k.pub ~bks ~msg in
data data
let revoke h_pub = let revoke h_pub =

8
test/test_crypto.ml
View file

@ -104,7 +104,7 @@ let () =
in in
let bks = blinding_key_secret |> decode in let bks = blinding_key_secret |> decode in
let msg = decode message_hash in let msg = decode message_hash in
let bmsg = Fdh_rsa.rsa_blind pub ~bks msg in let bmsg = Fdh_rsa.blind_msg pub ~bks msg in
assert (encode bmsg = blinded_message); assert (encode bmsg = blinded_message);
() ()
@ -116,8 +116,10 @@ let () =
let priv, pub = RsaPrivateKey.generate ~bits:2048 () in let priv, pub = RsaPrivateKey.generate ~bits:2048 () in
let bks = "deadbeaf" in let bks = "deadbeaf" in
let msg = "uhuh." in let msg = "uhuh." in
let sig_ = Fdh_rsa.sign ~priv ~pub ~bks ~msg in let bmsg = Fdh_rsa.blind_msg pub ~bks msg in
let res = Fdh_rsa.verify pub ~msg ~sig_ in let bsig = Fdh_rsa.sign ~key:priv bmsg in
let sig_ = Fdh_rsa.unblind_sig pub ~bks bsig in
let res = Fdh_rsa.verify ~key:pub sig_ ~msg in
assert (Result.is_ok res); assert (Result.is_ok res);
() ()