From 2ad5a6f90702bea2d171d61e7572917ce43b138e Mon Sep 17 00:00:00 2001
From: jrandom <jrandom>
Date: Fri, 12 May 2006 03:31:44 +0000
Subject: [PATCH] 2006-05-11  jrandom     * PRNG bugfix (thanks cervantes and
 Complication!)

---
 .../src/net/i2p/util/FortunaRandomSource.java | 49 ++++++++++++++++---
 history.txt                                   |  5 +-
 .../src/net/i2p/router/RouterVersion.java     |  4 +-
 3 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/core/java/src/net/i2p/util/FortunaRandomSource.java b/core/java/src/net/i2p/util/FortunaRandomSource.java
index 0ca277f84..74eb4938c 100644
--- a/core/java/src/net/i2p/util/FortunaRandomSource.java
+++ b/core/java/src/net/i2p/util/FortunaRandomSource.java
@@ -76,15 +76,33 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
         if (n<=0)
           throw new IllegalArgumentException("n must be positive");
 
-        if ((n & -n) == n)  // i.e., n is a power of 2
-            return (int)((n * (long)nextBits(31)) >> 31);
+        ////
+        // this shortcut from sun's docs neither works nor is necessary.
+        //
+        //if ((n & -n) == n)  {
+        //    // i.e., n is a power of 2
+        //    return (int)((n * (long)nextBits(31)) >> 31);
+        //}
 
-        int bits, val;
-        do {
-            bits = nextBits(31);
-            val = bits % n;
-        } while(bits - val + (n-1) < 0);
-        return val;
+        int numBits = 0;
+        int remaining = n;
+        int rv = 0;
+        while (remaining > 0) {
+            remaining >>= 1;
+            rv += nextBits(8) << numBits*8;
+            numBits++;
+        }
+        if (rv < 0)
+            rv += n;
+        return rv % n;
+        
+        //int bits, val;
+        //do {
+        //    bits = nextBits(31);
+        //    val = bits % n;
+        //} while(bits - val + (n-1) < 0);
+        //
+        //return val;
     }
 
     /**
@@ -180,4 +198,19 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
     public synchronized void feedEntropy(String source, byte[] data, int offset, int len) {
         _fortuna.addRandomBytes(data, offset, len);
     }
+    
+    public static void main(String args[]) {
+        try {
+            RandomSource rand = I2PAppContext.getGlobalContext().random();
+            java.io.ByteArrayOutputStream baos = new java.io.ByteArrayOutputStream();
+            java.util.zip.GZIPOutputStream gos = new java.util.zip.GZIPOutputStream(baos);
+            for (int i = 0; i < 1024*1024; i++) {
+                int c = rand.nextInt(256);
+                gos.write((byte)c);
+            }
+            gos.finish();
+            byte compressed[] = baos.toByteArray();
+            System.out.println("Compressed size of 1MB: " + compressed.length);
+        } catch (Exception e) { e.printStackTrace(); }
+    }
 }
diff --git a/history.txt b/history.txt
index ac8835954..052f3baf4 100644
--- a/history.txt
+++ b/history.txt
@@ -1,4 +1,7 @@
-$Id: history.txt,v 1.471 2006/05/07 22:19:46 complication Exp $
+$Id: history.txt,v 1.472 2006/05/09 16:17:17 jrandom Exp $
+
+2006-05-11  jrandom
+    * PRNG bugfix (thanks cervantes and Complication!)
 
 * 2006-05-09  0.6.1.18 released
 
diff --git a/router/java/src/net/i2p/router/RouterVersion.java b/router/java/src/net/i2p/router/RouterVersion.java
index 431d598db..61154d5d3 100644
--- a/router/java/src/net/i2p/router/RouterVersion.java
+++ b/router/java/src/net/i2p/router/RouterVersion.java
@@ -15,9 +15,9 @@ import net.i2p.CoreVersion;
  *
  */
 public class RouterVersion {
-    public final static String ID = "$Revision: 1.411 $ $Date: 2006/05/07 22:19:47 $";
+    public final static String ID = "$Revision: 1.412 $ $Date: 2006/05/09 16:17:22 $";
     public final static String VERSION = "0.6.1.18";
-    public final static long BUILD = 0;
+    public final static long BUILD = 1;
     public static void main(String args[]) {
         System.out.println("I2P Router version: " + VERSION + "-" + BUILD);
         System.out.println("Router ID: " + RouterVersion.ID);