Hi,
+-From: Lothar Kimmeringer <j...@kimmeringer.de> --
|_Date: Wed, 04 Jun 2014 18:25:11 +0200 __________
|
|Since DH-Keys > 1024 bytes aren't supported with Java VMs < 8,
|this KEX is removed from the list of supported KEXes. Problem
|"here" is that the system to be connected is only allowing
|precisely this KEX, so connections fail and the system in
|question needs to stay on Java 7 for a while, so updating
|to Java 8 is not an option at the moment.
According to the source code of com.sun.crypto.provider.DHKeyPairGenerator[1],
the following change will allow to use Diffie-Helman-Group-14 on java6 and
java7,
but it depends on a bug of DHKeyPairGenerator.
--- jsch-0.1.51/src/main/java/com/jcraft/jsch/jce/DH.java 2014-01-02
08:15:41.000000000 +0000
+++ jsch-0.1.51.group14/src/main/java/com/jcraft/jsch/jce/DH.java
2014-06-05 07:35:43.000000000 +0000
@@ -54,7 +54,12 @@
public byte[] getE() throws Exception{
if(e==null){
DHParameterSpec dhSkipParamSpec=new DHParameterSpec(p, g);
- myKpairGen.initialize(dhSkipParamSpec);
+ try{ myKpairGen.initialize(dhSkipParamSpec); }
+ catch(InvalidAlgorithmParameterException e){
+ String msg="Prime size must be multiple of 64, and can only range from
512 to 1024 (inclusive)";
+ if(!e.getMessage().equals(msg))
+ throw e;
+ }
KeyPair myKpair=myKpairGen.generateKeyPair();
myKeyAgree.init(myKpair.getPrivate());
// BigInteger
x=((javax.crypto.interfaces.DHPrivateKey)(myKpair.getPrivate())).getX();
[1]
http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/com/sun/crypto/provider/DHKeyPairGenerator.java#109
Sincerely,
--
Atsuhiko Yamanaka
JCraft,Inc.
1-14-20 HONCHO AOBA-KU,
SENDAI, MIYAGI 980-0014 Japan.
Tel +81-22-723-2150
Skype callto://jcraft/
Twitter: http://twitter.com/ymnk
Facebook: http://facebook.com/aymnk
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