java.security.SecureRandom in GCJ 4.0.2 has no impact, so SecureRandom always
uses the same weak seed. This has obvious security issues, though they'd take
a targetted attack to mount (e.g. force a JVM restart so the SecureRandom
reverts to the default seed - "new java.util.Random(0l).nextBytes(new
byte[20])", per gnu.java.security.provider.SHA1PRNG.ensureIsSeeded()).
[EMAIL PROTECTED] ~/dev/i2p/native $ gcj -o seed --main=seed seed.java
[EMAIL PROTECTED] ~/dev/i2p/native $ ./seed
Byte difference in a seeded PRNG: 0
Seed data:
8bc7ec2ec7c4f87a13ec6120616ead831baeaf40dfd0804c534145ddbd12c580926578f8e0fea3b8b69287e26841a91cfca9a63fa95e453494f495ff14c82
[EMAIL PROTECTED] ~/dev/i2p/native $ cat seed.java
import java.security.SecureRandom;
public class seed {
public static void main(String args[]) {
SecureRandom r = new SecureRandom();
byte unseededBuf[] = new byte[64];
r.nextBytes(unseededBuf);
r = new SecureRandom();
byte seededBuf[] = new byte[64];
r.setSeed(unseededBuf);
r.nextBytes(seededBuf);
int diffs = 0;
for (int i = 0; i < 64; i++) {
if (seededBuf[i] != unseededBuf[i])
diffs++;
}
System.out.println("Byte difference in a seeded PRNG: " + diffs);
System.out.print("Seed data: ");
for (int i = 0; i < 64; i++)
System.out.print(Integer.toHexString((int)(unseededBuf[i]&0xFF)));
System.out.println();
}
}
The secureRandom.getProvider().toString() returns
"gnu.java.security.provider.Gnu: name=GNU version=1.0", which in turn uses the
SHA1PRNG (in the 4.0.2 release, at least). The odd part is that the provider
should be taking into account the seed - engineSetSeed *looks* right, and
java.security.SecureRandom.java's setSeed just calls the spi.engineSetSeed, so
I'm not sure whats going on here.
=jr
--
Summary: SecureRandom.setSeed has no impact
Product: gcc
Version: 4.0.2
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: java
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jrandom-gcc at i2p dot net
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24481
