From 5916955b802d0b0d717df0cb4c60cf9e4284b677 Mon Sep 17 00:00:00 2001
From: Alhuda Khan <admin@research.digiscrypt.com>
Date: Wed, 14 Oct 2026 14:44:31 +0530
Subject: [PATCH 1/2] zncstring: generate RandomString with a CSPRNG instead of
 rand()

---
 src/ZNCString.cpp | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/ZNCString.cpp b/src/ZNCString.cpp
index c30469b9..04a32987 100644
--- a/src/ZNCString.cpp
+++ b/src/ZNCString.cpp
@@ -19,6 +19,7 @@
 #include <znc/Utils.h>
 #include <znc/MD5.h>
 #include <znc/SHA256.h>
+#include <random>
 #include <sstream>
 
 using std::stringstream;
@@ -998,12 +999,18 @@ CString CString::RandomString(unsigned int uLength) {
         "0123456789!?.,:;/*-+_()";
     // -1 because sizeof() includes the trailing '\0' byte
     const size_t len = sizeof(chars) / sizeof(chars[0]) - 1;
-    size_t p;
     CString sRet;
+    sRet.reserve(uLength);
+
+    // Draw from the system CSPRNG rather than rand(): this feeds web session
+    // ids (CWebSock::GetSession) and password salts (CUtils::GetSalt), and
+    // rand()'s stream is fully determined by the process seed set in
+    // seedPRNG() (startup time xored with the pid).
+    std::random_device rd;
+    std::uniform_int_distribution<size_t> distr(0, len - 1);
 
     for (unsigned int a = 0; a < uLength; a++) {
-        p = (size_t)(len * (rand() / (RAND_MAX + 1.0)));
-        sRet += chars[p];
+        sRet += chars[distr(rd)];
     }
 
     return sRet;

From 71dd0e0f8886b2fd8bf5fb6021e1538f8ad77af7 Mon Sep 17 00:00:00 2001
From: Alhuda Khan <admin@research.digiscrypt.com>
Date: Sun, 18 Oct 2026 12:22:56 +0530
Subject: [PATCH 2/2] zncstring: use openssl RAND_bytes for RandomString when
 available

---
 src/ZNCString.cpp | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/src/ZNCString.cpp b/src/ZNCString.cpp
index 04a32987..80093c0e 100644
--- a/src/ZNCString.cpp
+++ b/src/ZNCString.cpp
@@ -22,6 +22,10 @@
 #include <random>
 #include <sstream>
 
+#ifdef HAVE_LIBSSL
+#include <openssl/rand.h>
+#endif
+
 using std::stringstream;
 
 static constexpr unsigned char XX = 0xff;
@@ -1002,12 +1006,26 @@ CString CString::RandomString(unsigned int uLength) {
     CString sRet;
     sRet.reserve(uLength);
 
-    // Draw from the system CSPRNG rather than rand(): this feeds web session
-    // ids (CWebSock::GetSession) and password salts (CUtils::GetSalt), and
-    // rand()'s stream is fully determined by the process seed set in
-    // seedPRNG() (startup time xored with the pid).
-    std::random_device rd;
     std::uniform_int_distribution<size_t> distr(0, len - 1);
+#ifdef HAVE_LIBSSL
+    // OpenSSL's DRBG is seeded once and doesn't go back to the kernel for
+    // every call, unlike std::random_device.
+    struct {
+        using result_type = unsigned int;
+        static constexpr result_type min() { return 0; }
+        static constexpr result_type max() { return ~0u; }
+        result_type operator()() {
+            result_type r;
+            if (RAND_bytes(reinterpret_cast<unsigned char*>(&r), sizeof(r)) !=
+                1) {
+                r = std::random_device()();
+            }
+            return r;
+        }
+    } rd;
+#else
+    std::random_device rd;
+#endif
 
     for (unsigned int a = 0; a < uLength; a++) {
         sRet += chars[distr(rd)];