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* FortunaRandomSource:

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- Fix bug that wasted entropy in nextInt()
    - Improved synchronization
This commit is contained in:
zzz
2012-09-11 19:40:20 +00:00
parent d7b48a2256
commit db42d9ec37
3 changed files with 73 additions and 42 deletions
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2
core/java/src/gnu/crypto/prng/AsyncFortunaStandalone.java
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@@ -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()
*
*/

5
core/java/src/gnu/crypto/prng/BasePRNGStandalone.java
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@@ -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];
}

108
core/java/src/net/i2p/util/FortunaRandomSource.java
View File

@@ -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);
}
}
/*****