Why does SSL handshake give 'Could not generat

Question

When I make an SSL connection with some IRC servers (but not others - presumably due to the server's preferred encryption method) I get the following exception:

Caused by: java.lang.RuntimeException: Could not generate DH keypair
    at com.sun.net.ssl.internal.ssl.DHCrypt.<init>(DHCrypt.java:106)
    at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverKeyExchange(ClientHandshaker.java:556)
    at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:183)
    at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Handshaker.java:593)
    at com.sun.net.ssl.internal.ssl.Handshaker.process_record(Handshaker.java:529)
    at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:893)
    at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1138)
    at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1165)
    ... 3 more

Final cause:

Caused by: java.security.InvalidAlgorithmParameterException: Prime size must be multiple of 64, and can only range from 512 to 1024 (inclusive)
    at com.sun.crypto.provider.DHKeyPairGenerator.initialize(DashoA13*..)
    at java.security.KeyPairGenerator$Delegate.initialize(KeyPairGenerator.java:627)
    at com.sun.net.ssl.internal.ssl.DHCrypt.<init>(DHCrypt.java:100)
    ... 10 more

An example of a server that demonstrates this problem is aperture.esper.net:6697 (this is an IRC server). An example of a server that does not demonstrate the problem is kornbluth.freenode.net:6697. [Not surprisingly, all servers on each network share the same respective behaviour.]

My code (which as noted does work when connecting to some SSL servers) is:

    SSLContext sslContext = SSLContext.getInstance("SSL");
    sslContext.init(null, trustAllCerts, new SecureRandom());
    s = (SSLSocket)sslContext.getSocketFactory().createSocket();
    s.connect(new InetSocketAddress(host, port), timeout);
    s.setSoTimeout(0);
    ((SSLSocket)s).startHandshake();

It's that last startHandshake that throws the exception. And yes there is some magic going on with the 'trustAllCerts'; that code forces the SSL system not to validate certs. (So... not a cert problem.)

Obviously one possibility is that esper's server is misconfigured, but I searched and didn't find any other references to people having problems with esper's SSL ports, and 'openssl' connects to it (see below). So I'm wondering if this is a limitation of Java default SSL support, or something. Any suggestions?

Here's what happens when I connect to aperture.esper.net 6697 using 'openssl' from commandline:

~ $ openssl s_client -connect aperture.esper.net:6697
CONNECTED(00000003)
depth=0 /C=GB/ST=England/L=London/O=EsperNet/OU=aperture.esper.net/CN=*.esper.net/emailAddress=[e-mail]
verify error:num=18:self signed certificate
verify return:1
depth=0 /C=GB/ST=England/L=London/O=EsperNet/OU=aperture.esper.net/CN=*.esper.net/emailAddress=[e-mail]
verify return:1
---
Certificate chain
 0 s:/C=GB/ST=England/L=London/O=EsperNet/OU=aperture.esper.net/CN=*.esper.net/emailAddress=[e-mail]
   i:/C=GB/ST=England/L=London/O=EsperNet/OU=aperture.esper.net/CN=*.esper.net/emailAddress=[e-mail]
---
Server certificate
-----BEGIN CERTIFICATE-----
[There was a certificate here, but I deleted it to save space]
-----END CERTIFICATE-----
subject=/C=GB/ST=England/L=London/O=EsperNet/OU=aperture.esper.net/CN=*.esper.net/emailAddress=[e-mail]
issuer=/C=GB/ST=England/L=London/O=EsperNet/OU=aperture.esper.net/CN=*.esper.net/emailAddress=[e-mail]
---
No client certificate CA names sent
---
SSL handshake has read 2178 bytes and written 468 bytes
---
New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-SHA
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1
    Cipher    : DHE-RSA-AES256-SHA
    Session-ID: 51F1D40A1B044700365D3BD1C61ABC745FB0C347A334E1410946DCB5EFE37AFD
    Session-ID-ctx: 
    Master-Key: DF8194F6A60B073E049C87284856B5561476315145B55E35811028C4D97F77696F676DB019BB6E271E9965F289A99083
    Key-Arg   : None
    Start Time: 1311801833
    Timeout   : 300 (sec)
    Verify return code: 18 (self signed certificate)
---

As noted, after all that, it does connect successfully which is more than you can say for my Java app.

Should it be relevant, I'm using OS X 10.6.8, Java version 1.6.0_26.

Answer 1

I have the same problem with Yandex Maps server, JDK 1.6 and Apache HttpClient 4.2.1. The error was

javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated

with enabled debug by -Djavax.net.debug=all there was a message in a log

Could not generate DH keypair

I have fixed this problem by adding BouncyCastle library bcprov-jdk16-1.46.jar and registering a provider in a map service class

public class MapService {

    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    public GeocodeResult geocode() {

    }

}

A provider is registered at the first usage of MapService.

Answer 2

Try downloading "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" from the Java download site and replacing the files in your JRE.

This worked for me and I didn't even need to use BouncyCastle - the standard Sun JCE was able to connect to the server.

PS. I got the same error (ArrayIndexOutOfBoundsException: 64) when I tried using BouncyCastle before changing the policy files, so it seems our situation is very similar.

Answer 3

You can installing the provider dynamically:

1) Download these jars:

• bcprov-jdk15on-152.jar
• bcprov-ext-jdk15on-152.jar

2) Copy jars to WEB-INF/lib (or your classpath)

3) Add provider dynamically:

import org.bouncycastle.jce.provider.BouncyCastleProvider;

...

Security.addProvider(new BouncyCastleProvider());

Answer 4

Solved the problem by upgrading to JDK 8.

Answer 5

If the server supports a cipher that does not include DH, you can force the client to select that cipher and avoid the DH error. Such as:

String pickedCipher[] ={"TLS_RSA_WITH_AES_256_CBC_SHA"};
sslsocket.setEnabledCipherSuites(pickedCipher);

Keep in mind that specifying an exact cipher is prone to breakage in the long run.

Answer 6

I encountered the SSL error on a CentOS server running JDK 6.

My plan was to install a higher JDK version (JDK 7) to co-exist with JDK 6 but it turns out that merely installing the newer JDK with rpm -i was not enough.

The JDK 7 installation would only succeed with the rpm -U upgrade option as illustrated below.

1. Download JDK 7

wget -O /root/jdk-7u79-linux-x64.rpm --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; o raclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/7u79-b15/jdk-7u79-linux-x64.rpm"

2. RPM installation fails

rpm -ivh jdk-7u79-linux-x64.rpm
Preparing...                ########################################### [100%]
        file /etc/init.d/jexec from install of jdk-2000:1.7.0_79-fcs.x86_64 conflicts with file from package jdk-2000:1.6.0_43-fcs.x86_64

3. RPM upgrade succeeds

rpm -Uvh jdk-7u79-linux-x64.rpm
Preparing...                ########################################### [100%]
   1:jdk                    ########################################### [100%]
Unpacking JAR files...
        rt.jar...
        jsse.jar...
        charsets.jar...
        tools.jar...
        localedata.jar...
        jfxrt.jar...

4. Confirm the new version

java -version
java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)