From db42d9ec373e432ff975688aa179950f6bb6f592 Mon Sep 17 00:00:00 2001
From: zzz <zzz@mail.i2p>
Date: Tue, 11 Sep 2012 19:40:20 +0000
Subject: [PATCH] * FortunaRandomSource: - Fix bug that wasted entropy in
nextInt() - Improved synchronization
---
.../crypto/prng/AsyncFortunaStandalone.java | 2 +-
.../gnu/crypto/prng/BasePRNGStandalone.java | 5 +-
.../src/net/i2p/util/FortunaRandomSource.java | 108 ++++++++++++------
3 files changed, 73 insertions(+), 42 deletions(-)
diff --git a/core/java/src/gnu/crypto/prng/AsyncFortunaStandalone.java b/core/java/src/gnu/crypto/prng/AsyncFortunaStandalone.java
index 71c9ed60c5..46e994695d 100644
--- a/core/java/src/gnu/crypto/prng/AsyncFortunaStandalone.java
+++ b/core/java/src/gnu/crypto/prng/AsyncFortunaStandalone.java
@@ -14,7 +14,7 @@ import net.i2p.util.Log;
*
* Note that this class is not fully Thread safe!
* The following methods must be synchronized externally, they are not
- * sycned here or in super():
+ * synced here or in super():
* addRandomByte(), addRandomBytes(), nextByte(), nextBytes(), seed()
*
*/
diff --git a/core/java/src/gnu/crypto/prng/BasePRNGStandalone.java b/core/java/src/gnu/crypto/prng/BasePRNGStandalone.java
index 6b71330d86..4b88e0f0b5 100644
--- a/core/java/src/gnu/crypto/prng/BasePRNGStandalone.java
+++ b/core/java/src/gnu/crypto/prng/BasePRNGStandalone.java
@@ -55,7 +55,7 @@ public abstract class BasePRNGStandalone implements IRandomStandalone {
// -------------------------------------------------------------------------
/** The canonical name prefix of the PRNG algorithm. */
- protected String name;
+ protected final String name;
/** Indicate if this instance has already been initialised or not. */
protected boolean initialised;
@@ -75,10 +75,7 @@ public abstract class BasePRNGStandalone implements IRandomStandalone {
* @param name the canonical name of this instance.
*/
protected BasePRNGStandalone(String name) {
- super();
-
this.name = name;
- initialised = false;
buffer = new byte[0];
}
diff --git a/core/java/src/net/i2p/util/FortunaRandomSource.java b/core/java/src/net/i2p/util/FortunaRandomSource.java
index 6d57f1c6cc..2209785cf6 100644
--- a/core/java/src/net/i2p/util/FortunaRandomSource.java
+++ b/core/java/src/net/i2p/util/FortunaRandomSource.java
@@ -49,12 +49,16 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
* @since 0.8.8
*/
public void shutdown() {
- _fortuna.shutdown();
+ synchronized(_fortuna) {
+ _fortuna.shutdown();
+ }
}
@Override
- public synchronized void setSeed(byte buf[]) {
- _fortuna.addRandomBytes(buf);
+ public void setSeed(byte buf[]) {
+ synchronized(_fortuna) {
+ _fortuna.addRandomBytes(buf);
+ }
}
/**
@@ -93,16 +97,21 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
// return (int)((n * (long)nextBits(31)) >> 31);
//}
- int numBits = 0;
- int remaining = n;
- int rv = 0;
- while (remaining > 0) {
- remaining >>= 1;
- rv += nextBits(8) << numBits*8;
- numBits++;
+ // get at least 4 extra bits if possible for better
+ // distribution after the %
+ int numBits;
+ if (n > 0xfffff)
+ numBits = 31;
+ else if (n > 0xfff)
+ numBits = 24;
+ else if (n > 0xf)
+ numBits = 16;
+ else
+ numBits = 8;
+ int rv;
+ synchronized(_fortuna) {
+ rv = nextBits(numBits);
}
- if (rv < 0)
- rv += n;
return rv % n;
//int bits, val;
@@ -121,7 +130,7 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
@Override
public long nextLong(long n) {
if (n == 0) return 0;
- long rv = signedNextLong(n);
+ long rv = signedNextLong();
if (rv < 0)
rv = 0 - rv;
rv %= n;
@@ -129,25 +138,31 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
}
@Override
- public long nextLong() { return signedNextLong(Long.MAX_VALUE); }
+ public long nextLong() { return signedNextLong(); }
/**
* Implementation from Sun's java.util.Random javadocs
*/
- private long signedNextLong(long n) {
- return ((long)nextBits(32) << 32) + nextBits(32);
+ private long signedNextLong() {
+ synchronized(_fortuna) {
+ return ((long)nextBits(32) << 32) + nextBits(32);
+ }
}
@Override
- public synchronized boolean nextBoolean() {
- // wasteful, might be worth caching the boolean byte later
- byte val = _fortuna.nextByte();
- return ((val & 0x01) == 1);
+ public boolean nextBoolean() {
+ byte val;
+ synchronized(_fortuna) {
+ val = _fortuna.nextByte();
+ }
+ return ((val & 0x01) != 0);
}
@Override
- public synchronized void nextBytes(byte buf[]) {
- _fortuna.nextBytes(buf);
+ public void nextBytes(byte buf[]) {
+ synchronized(_fortuna) {
+ _fortuna.nextBytes(buf);
+ }
}
/**
@@ -156,8 +171,10 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
* @since 0.8.12
*/
@Override
- public synchronized void nextBytes(byte buf[], int offset, int length) {
- _fortuna.nextBytes(buf, offset, length);
+ public void nextBytes(byte buf[], int offset, int length) {
+ synchronized(_fortuna) {
+ _fortuna.nextBytes(buf, offset, length);
+ }
}
/**
@@ -165,24 +182,35 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
*/
@Override
public double nextDouble() {
- return (((long)nextBits(26) << 27) + nextBits(27)) / (double)(1L << 53);
+ long d;
+ synchronized(_fortuna) {
+ d = ((long)nextBits(26) << 27) + nextBits(27);
+ }
+ return d / (double)(1L << 53);
}
+
/**
* Implementation from sun's java.util.Random javadocs
*/
@Override
public float nextFloat() {
- return nextBits(24) / ((float)(1 << 24));
+ int d;
+ synchronized(_fortuna) {
+ d = nextBits(24);
+ }
+ return d / ((float)(1 << 24));
}
+
/**
* Implementation from sun's java.util.Random javadocs
*/
@Override
- public synchronized double nextGaussian() {
- if (_haveNextGaussian) {
- _haveNextGaussian = false;
- return _nextGaussian;
- } else {
+ public double nextGaussian() {
+ synchronized (this) {
+ if (_haveNextGaussian) {
+ _haveNextGaussian = false;
+ return _nextGaussian;
+ }
double v1, v2, s;
do {
v1 = 2 * nextDouble() - 1; // between -1.0 and 1.0
@@ -197,10 +225,12 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
}
/**
- * Pull the next numBits of random data off the fortuna instance (returning -2^numBits-1
+ * Pull the next numBits of random data off the fortuna instance (returning 0
* through 2^numBits-1
+ *
+ * Caller must synchronize!
*/
- protected synchronized int nextBits(int numBits) {
+ protected int nextBits(int numBits) {
long rv = 0;
int bytes = (numBits + 7) / 8;
for (int i = 0; i < bytes; i++)
@@ -218,14 +248,18 @@ public class FortunaRandomSource extends RandomSource implements EntropyHarveste
/** reseed the fortuna */
@Override
- public synchronized void feedEntropy(String source, long data, int bitoffset, int bits) {
- _fortuna.addRandomByte((byte)(data & 0xFF));
+ public void feedEntropy(String source, long data, int bitoffset, int bits) {
+ synchronized(_fortuna) {
+ _fortuna.addRandomByte((byte)(data & 0xFF));
+ }
}
/** reseed the fortuna */
@Override
- public synchronized void feedEntropy(String source, byte[] data, int offset, int len) {
- _fortuna.addRandomBytes(data, offset, len);
+ public void feedEntropy(String source, byte[] data, int offset, int len) {
+ synchronized(_fortuna) {
+ _fortuna.addRandomBytes(data, offset, len);
+ }
}
/*****
--
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