SFTP connection Failed due to java.security.InvalidAlgorithmParameterException

Question

I am trying to connect to password less configured server using SFTP. Sftp connection is successful using terminal. But when I am connecting in JAVA (using Jsch library) through username and password, I am unable to connect. My java code:-

try {
        try {
            jsch.addIdentity(ftp_Info.getSftpCertFile());
        } catch (Exception e) {
            // TODO: Add a log message
        }
        session = jsch.getSession(ftp_Info.getUserName(), ftp_Info.getHost(), ftp_Info.getPort());
        String pswd = (password_encypted) // password encryption
        session.setPassword(pswd);
        session.setConfig("StrictHostKeyChecking", "no");
        session.setConfig("PreferredAuthentications", "password,hostbased,publickey");
        session.connect(); // exception occurred here
        session.setTimeout(connectionTimeOut);
        Channel channel = session.openChannel(SFTP);
        channel.connect();
        sftpChannel = (ChannelSftp) channel;

    } catch (Exception e) {
        log.error(e.getMessage(), e);//error logged here
    }

I am getting following exception :-

com.jcraft.jsch.JSchException: Session.connect: java.security.InvalidAlgorithmParameterException: Prime size must be multiple of 64, and can only range from 512 to 1024 (inclusive) at com.jcraft.jsch.Session.connect(Session.java:485) at com.jcraft.jsch.Session.connect(Session.java:149)

Please help in troubleshooting or resolving it. Is there any way except any third party service provider to make my 2048 bit key pass this exception?

I suspect this is a problem with your crypto suite. You are probably going to want to switch to use BouncyCastle provider. What JDK are you using? — M. Rizzo
– M. Rizzo, Commented Jul 25, 2017 at 13:37

M. Rizzo · Accepted Answer · 2017-07-25 14:18:54Z

2

Under 1.7, I will assume you are utilizing maven for your project. I would add the bouncycastle dependency to your pom.

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk16</artifactId>
    <version>1.45</version>
</dependency>

This should work fine with jdk 7.

Then add a line of code to add the BouncyCastle provider as the 1st provider.

Security.insertProviderAt(new BouncyCastleProvider(),1);

I would place that prior to your getSftpCertFile() call and prior to any SSL related code. If you are not using Maven or have a different infrastructure, please let me know. You could configure the security provider at the JRE level, but I would always prefer to configure at the project level if possible to not impact other projects.

answered Jul 25, 2017 at 14:18

M. Rizzo

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3 Comments

Raghav Agarwal Over a year ago

My key size is 2048 bit, and I think thats the reason I am getting the exception. Will jdk1.8 will make it work or bountyCastleProvider. If jdk1.8 wil work than that will be more feasible.

M. Rizzo Over a year ago

The issue with the JCE imposing an artificial restricition on the Diffie-Hellman primes (JDK-651495) should have been in addressed in JDK8u56. So as long as you use a JDK8u56 or later this should address the problem.

Raghav Agarwal Over a year ago

Thanks for your help @M.Rizzo

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