From 5e3bad2f86665b35155095b91a2d672fc7335870 Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Sat, 30 Nov 2013 12:02:56 -0500
Subject: Refactor random data generation

Add new RandomDataProvider object and implement existing random number
generation in terms of that.  This enables end users to supply their
own random data providers.
---
 libqpdf/InsecureRandomDataProvider.cc | 49 +++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 libqpdf/InsecureRandomDataProvider.cc

(limited to 'libqpdf/InsecureRandomDataProvider.cc')

diff --git a/libqpdf/InsecureRandomDataProvider.cc b/libqpdf/InsecureRandomDataProvider.cc
new file mode 100644
index 00000000..5f637746
--- /dev/null
+++ b/libqpdf/InsecureRandomDataProvider.cc
@@ -0,0 +1,49 @@
+#include <qpdf/InsecureRandomDataProvider.hh>
+
+#include <qpdf/qpdf-config.h>
+#include <qpdf/QUtil.hh>
+#include <stdlib.h>
+
+InsecureRandomDataProvider::InsecureRandomDataProvider() :
+    seeded_random(false)
+{
+}
+
+InsecureRandomDataProvider::~InsecureRandomDataProvider()
+{
+}
+
+void
+InsecureRandomDataProvider::provideRandomData(unsigned char* data, size_t len)
+{
+    for (size_t i = 0; i < len; ++i)
+    {
+        data[i] = static_cast<unsigned char>((this->random() & 0xff0) >> 4);
+    }
+}
+
+long
+InsecureRandomDataProvider::random()
+{
+    if (! this->seeded_random)
+    {
+	// Seed the random number generator with something simple, but
+	// just to be interesting, don't use the unmodified current
+	// time.  It would be better if this were a more secure seed.
+        QUtil::srandom(QUtil::get_current_time() ^ 0xcccc);
+	this->seeded_random = true;
+    }
+
+#  ifdef HAVE_RANDOM
+    return ::random();
+#  else
+    return rand();
+#  endif
+}
+
+RandomDataProvider*
+InsecureRandomDataProvider::getInstance()
+{
+    static InsecureRandomDataProvider instance;
+    return &instance;
+}
-- 
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