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authorPeter Dettman <peter.dettman@bouncycastle.org>2016-03-10 14:05:15 +0700
committerPeter Dettman <peter.dettman@bouncycastle.org>2016-03-10 14:05:15 +0700
commitefb5751fec2aad9cfa98922b11879f9e4efed59d (patch)
treeab905a1eb75f1fe35e18648c7f7be9b0563f4997 /crypto/src/security/SecureRandom.cs
parentImplement unique name_type restriction from RFC 6066 (diff)
downloadBouncyCastle.NET-ed25519-efb5751fec2aad9cfa98922b11879f9e4efed59d.tar.xz
Prefer high bits for powers-of-two
Diffstat (limited to 'crypto/src/security/SecureRandom.cs')
-rw-r--r--crypto/src/security/SecureRandom.cs8
1 files changed, 6 insertions, 2 deletions
diff --git a/crypto/src/security/SecureRandom.cs b/crypto/src/security/SecureRandom.cs
index cb831acc2..bd639a336 100644
--- a/crypto/src/security/SecureRandom.cs
+++ b/crypto/src/security/SecureRandom.cs
@@ -170,6 +170,7 @@ namespace Org.BouncyCastle.Security
 
         public override int Next(int maxValue)
         {
+
             if (maxValue < 2)
             {
                 if (maxValue < 0)
@@ -178,13 +179,16 @@ namespace Org.BouncyCastle.Security
                 return 0;
             }
 
+            int bits;
+
             // Test whether maxValue is a power of 2
             if ((maxValue & (maxValue - 1)) == 0)
             {
-                return NextInt() & (maxValue - 1);
+                bits = NextInt() & int.MaxValue;
+                return (int)(((long)bits * maxValue) >> 31);
             }
 
-            int bits, result;
+            int result;
             do
             {
                 bits = NextInt() & int.MaxValue;