ssh_client/third_party/openssh-git/openssh-git-sntrup761-random.patch

https://github.com/openssh/openssh-portable/pull/621

From a06e67d6bd44c110bd8ded16ac0751598335d6e6 Mon Sep 17 00:00:00 2001
From: Mike Frysinger <vapier@chromium.org>
Date: Tue, 13 Jan 2026 19:00:08 -0500
Subject: [PATCH] optimize random calls

randombytes is implemented on top of arc4random_buf which, depending
on the system, might involve a syscall to get bytes.  Linux can often
optimize this with a vsyscall to lessen the pain.

The urandom32 function will grab 4 bytes and then manually convert
them to a 32-bit number instead of just writing directly.

The Short_random & Small_random both call urandom32 p times (where
p is defined as 761) to fill another buffer.  This means 1500+ calls
to get 4 random bytes at a time.  Both functions can simply fill the
buffer in one go which means 2 calls to get 4*761 bytes each, and
then drop the unoptimized urandom32 function entirely.
---
 sntrup761.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/sntrup761.c b/sntrup761.c
index 123d01381c61..9c734f221657 100644
--- a/sntrup761.c
+++ b/sntrup761.c
@@ -1961,25 +1961,17 @@ static void Hash_prefix(unsigned char *out, int b, const unsigned char *in, int
   for (i = 0; i < 32; ++i) out[i] = h[i];
 }
 
-static uint32_t urandom32(void) {
-  unsigned char c[4];
-  uint32_t result = 0;
-  int i;
-  randombytes(c, 4);
-  for (i = 0; i < 4; ++i) result += ((uint32_t)c[i]) << (8 * i);
-  return result;
-}
-
 static void Short_random(small *out) {
   uint32_t L[p];
-  int i;
-  for (i = 0; i < p; ++i) L[i] = urandom32();
+  randombytes(L, sizeof(L));
   Short_fromlist(out, L);
 }
 
 static void Small_random(small *out) {
   int i;
-  for (i = 0; i < p; ++i) out[i] = (((urandom32() & 0x3fffffff) * 3) >> 30) - 1;
+  uint32_t L[p];
+  randombytes(L, sizeof(L));
+  for (i = 0; i < p; ++i) out[i] = (((L[i] & 0x3fffffff) * 3) >> 30) - 1;
 }
 
 static void KeyGen(Fq *h, small *f, small *ginv) {
-- 
2.39.5