~

src/fdh_rsa.ml

@@ -64,29 +64,12 @@ let rsa_blind pub ~bks ~msg =
   let data_r_e = Z.rem (Z.mul data r_e) pub.n in
   Z_extra.to_octets_be data_r_e
 
-(* -- WIP crypto -- *)
-
 (* decrypt <=> sign *)
-let rsa_sign_z priv r =
-  let data = Z_extra.to_octets_be r in
-  Mirage_crypto_pk.Rsa.decrypt ~crt_hardening:true ~key:priv data
-
-(* TODO crypto
-   look into mirage-crypto for this
-   use Eqaf for constant time string compare *)
-let rsa_verify_z pub r sig_ =
-  let data = Z_extra.to_octets_be r in
-  let sig_' = Mirage_crypto_pk.Rsa.encrypt ~key:pub data in
-  match String.equal sig_ sig_' with
-  | false -> Fmt.error "RSA signature verification failed"
-  | true -> Ok ()
-
-let rsa_sign_fdh priv msg =
-  let pub = RsaPrivateKey.pub_of_priv priv in
-  let r = rsa_full_domain_hash pub msg in
-  rsa_sign_z priv r
+let rsa_sign_blinded priv ~bmsg =
+  Mirage_crypto_pk.Rsa.decrypt ~crt_hardening:true ~key:priv bmsg
 
 let rsa_unblind pub ~bks ~sig_ =
+  let data = Z_extra.of_octets_be sig_ in
   let bkey = rsa_blinding_key_derive pub bks in
   let r_inv =
     try Z.invert bkey pub.n
@@ -94,9 +77,16 @@ let rsa_unblind pub ~bks ~sig_ =
       (* => gcd(r,n) <> 1, should be already checked for *)
       assert false
   in
-  let ubsig = Z.rem (Z.mul sig_ r_inv) pub.n in
-  ubsig
+  let data = Z.rem (Z.mul data r_inv) pub.n in
+  Z_extra.to_octets_be data
 
+(* TODO crypto
+   look into mirage-crypto for this
+   at least use Eqaf for constant time string compare *)
 let rsa_verify pub ~msg ~sig_ =
-  let r = rsa_full_domain_hash pub msg in
-  rsa_verify_z pub r sig_
+  let msg_fdh = rsa_full_domain_hash pub msg in
+  let s1 = Z_extra.to_octets_be msg_fdh in
+  let s2 = Mirage_crypto_pk.Rsa.encrypt ~key:pub sig_ in
+  match String.equal s1 s2 with
+  | false -> Fmt.error "RSA signature verification failed"
+  | true -> Ok ()