Hi Pasi,
Thank you for your patience, and contribution to OpenJDK. The bug is
accepted, and you should be able to review it at:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8014618
Let's use the above bug ID to track the issue.
Your patch looks fine in general (I may have some very minor comments
later). We also have similar problems in PKCS11 provider because of the
update of P11KeyAgreement.java in changeset:
http://hg.openjdk.java.net/jdk7u/jdk7u-gate/jdk/rev/e574e475c8a6
Would you like to also fix it in your patch?
Thanks again for your nice work.
Regards,
Xuelei
On 5/10/2013 5:00 PM, Pasi Eronen wrote:
AKA 1 out of 256 SSL/TLS handshakes fails with DHE cipher suites
I reported this bug over a month of ago, but for some reason, it's not
yet visible at bugs.sun.com http://bugs.sun.com. I've included the bug
report below just in
case.
It seems this commit from March 2012 inadvertently broke SSL/TLS DHE
cipher suites, causing the SSL/TLS handshake to fail approximately
1 out of 256 times:
http://hg.openjdk.java.net/jdk7u/jdk7u-gate/jdk/rev/e574e475c8a6
The commit was done to fix this bug:
http://bugs.sun.com/view_bug.do?bug_id=7146728
While generating a secret of the same length as modulus may be the right
choice generally speaking (and it's what e.g. IPsec uses), SSL/TLS uses
a different convention: leading zeroes must be stripped.
This is currently blocking us from updating our production systems to
Java 7, so although I have not contributed to OpenJDK before, I'd like
to submit a patch and a test case for this (I've signed the OCA
already). But before I do this, I'd like to check that the approach is
agreeable.
We have a separate algorithm value TlsPremasterSecret, so
behavior for other cases could stay the same. Would a patch
like this:
} else if (algorithm.equals(TlsPremasterSecret)) {
// remove leading zero bytes per RFC 5246 Section 8.1.2
int i = 0;
while ((i secret.length - 1) (secret[i] == 0)) {
i++;
}
if (i == 0) {
return new SecretKeySpec(secret, TlsPremasterSecret);
} else {
byte[] secret2 = new byte[secret.length - i];
System.arraycopy(secret, i, secret2, 0, secret2.length);
return new SecretKeySpec(secret2, TlsPremasterSecret);
}
}
Plus a test case (with fixed keys) that checks that leading zero is
stripped
for TlsPremasterSecret and is not stripped otherwise, be sufficient?
Best regards,
Pasi
---snip---
Synopsis:
DHKeyAgreement calculates wrong TlsPremasterSecret 1 out of 256 times
Full OS version:
Tested on Windows 7 (Microsoft Windows [Version 6.1.7601]), but occurs in
e..g OpenJDK 7 as well.
Development Kit or Runtime version:
java version 1.7.0_17
Java(TM) SE Runtime Environment (build 1.7.0_17-b02)
Java HotSpot(TM) Client VM (build 23.7-b01, mixed mode, sharing)
Description:
When performing Diffie-Hellman key agreement for SSL/TLS, the TLS
specification (RFC 5246) says that Leading bytes of Z that contain all zero
bits are stripped before it is used as the pre_master_secret.
However, com.sun.crypto.provider.DHKeyAgreement.java does not strip leading
zero bytes. This causes approximately 1 out 256 SSL/TLS handshakes with
DH/DHE cipher suites to fail (when the leading byte happens, by chance, to
be zero).
Steps to Reproduce:
1. Start a simple JSSE socket server with -Djavax.net.debug=all.
2. Connect to the server with e.g. OpenSSL command line tool, ensuring that
DHE cipher suite gets selected (e.g. openssl s_client -cipher
DHE-RSA-AES128-SHA -connect 192.168.81.1:
http://192.168.81.1:) repeatedly. Other SSL
clients can be used -- this is not an OpenSSL bug (see below).
3. Repeat the connection. After a couple of hundred successful connections,
the connection will fail with handshake_failure alert.
4. Examine the JSSE debug logs produced by the server: the failed connection
will have a PreMaster secret that begins with zero byte
(while all other connections have non-zero byte here). For example:
SESSION KEYGEN:
PreMaster Secret:
: 00 70 C5 7E 91 38 C8 DE ED 75 3D 76 8A B5 44 69 .p...8...u=v..Di
0010: E7 32 1C EE 80 77 50 C7 A9 51 24 2E E3 15 11 30 .2...wP..Q$0
0020: 9D F6 9F BC 9D EB 5C 18 F7 A4 19 ED 1A AC 2E 0C ..\.
0030: E3 18 C5 11 B1 80 07 7D B1 C6 70 A8 D7 EB CF DD ..p.
0040: 2D B5 1D BC 01 3E 28 2A 2B 5B 38 8F EB 20 F2 A2 -(*+[8.. ..
0050: 00 07 47 F7 87 B8 99 CB EF B4 13 04 C8 8B 82 FB ..G.
Expected Result:
Expected result is that every connection succeed.
Actual Result:
Roughly one out of 256 connections fail.
Source code for an executable test case:
Java server:
import javax.net.ssl.SSLServerSocket;
import javax.net.ssl.SSLServerSocketFactory;
import javax.net.ssl.SSLSocket;
public class TestServer
