From 2521630cecd485bf07019ca179048c511984b89a Mon Sep 17 00:00:00 2001
From: Hannes Mehnert <hannes@mehnert.org>
Date: Mon, 11 Mar 2024 12:53:37 +0100
Subject: [PATCH] use rng.generate_into

---
 pk/z_extra.ml     |  8 +++++---
 src/uncommon.ml   |  2 +-
 tests/test_rsa.ml | 12 ++++++------
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/pk/z_extra.ml b/pk/z_extra.ml
index ece5c53e..caf896f9 100644
--- a/pk/z_extra.ml
+++ b/pk/z_extra.ml
@@ -126,9 +126,11 @@ let set_msb bits buf =
     go bits 0
 
 let gen_bits ?g ?(msb = 0) bits =
-  let res = Bytes.unsafe_of_string (Mirage_crypto_rng.generate ?g (bits // 8)) in
-  set_msb msb res ;
-  of_octets_be ~bits (Bytes.unsafe_to_string res)
+  let bytelen = bits // 8 in
+  let buf = Bytes.create bytelen in
+  Mirage_crypto_rng.generate_into ?g buf ~off:0 bytelen;
+  set_msb msb buf ;
+  of_octets_be ~bits (Bytes.unsafe_to_string buf)
 
 (* Invalid combinations of ~bits and ~msb will loop forever, but there is no
  * way to quickly determine upfront whether there are any primes in the
diff --git a/src/uncommon.ml b/src/uncommon.ml
index e186aaa8..ca23e16b 100644
--- a/src/uncommon.ml
+++ b/src/uncommon.ml
@@ -23,7 +23,7 @@ let xor_into src dst n =
 
 let xor a b =
   assert (String.length a = String.length b);
-  let b' = Bytes.copy (Bytes.unsafe_of_string b) in
+  let b' = Bytes.of_string b in
   xor_into a b' (Bytes.length b');
   Bytes.unsafe_to_string b'
 
diff --git a/tests/test_rsa.ml b/tests/test_rsa.ml
index f512ba4d..9de56916 100644
--- a/tests/test_rsa.ml
+++ b/tests/test_rsa.ml
@@ -83,12 +83,12 @@ let rsa_selftest ~bits n =
   "selftest" >:: times ~n @@ fun _ ->
     let msg =
       let size = bits // 8 in
-      let cs = Mirage_crypto_rng.generate size
-      and i  = 1 + Randomconv.int ~bound:(pred size) Mirage_crypto_rng.generate in
-      let cs = Bytes.unsafe_of_string cs in
-      Bytes.set_uint8 cs 0 0;
-      Bytes.(set_uint8 cs i (get_uint8 cs i lor 2));
-      Bytes.unsafe_to_string cs
+      let buf = Bytes.create size in
+      Mirage_crypto_rng.generate_into buf ~off:0 size;
+      let i  = 1 + Randomconv.int ~bound:(pred size) Mirage_crypto_rng.generate in
+      Bytes.set_uint8 buf 0 0;
+      Bytes.(set_uint8 buf i (get_uint8 buf i lor 2));
+      Bytes.unsafe_to_string buf
     in
     let key = gen_rsa ~bits in
     let enc = Rsa.(encrypt ~key:(pub_of_priv key) msg) in