using (SvnClient client = new SvnClient())
    {
        client.Authentication.Clear();  // Clear a previous authentication
        client.Authentication.DefaultCredentials = new System.Net.NetworkCredential("user1", "pass1");

        SvnCommitArgs ca = new SvnCommitArgs();
        ca.LogMessage = "svn log message created at " + DateTime.Now.ToString();
        bool action = client.Commit(@"C:demo_repodemo_projecttrunkfile.txt", ca);
    }

using (SvnClient client = new SvnClient())
    {
        client.SetProperty(("", "svn:author", "user1");

        SvnCommitArgs ca = new SvnCommitArgs();
        ca.LogMessage = "svn log message created at " + DateTime.Now.ToString();
        bool action = client.Commit(@"C:demo_repodemo_projecttrunkfile.txt", ca);
    }

using (SvnClient client = new SvnClient())
    {
        client.Authentication.Clear(); // Clear predefined handlers
        client.Authentication.UserNamePasswordHandlers
            += delegate(object obj, SharpSvn.Security.SvnUserNamePasswordEventArgs args)
        {
            args.UserName = "user1";
            args.Password = "pass1";
        };

        SvnCommitArgs ca = new SvnCommitArgs();
        ca.LogMessage = "svn log message created at " + DateTime.Now.ToString();
        bool action = client.Commit(@"C:demo_repodemo_projecttrunkfile.txt", ca);
    }

client.Authentication.Clear(); // Clear predefined handlers
            client.Authentication.UserNamePasswordHandlers
                += delegate(object obj, SharpSvn.Security.SvnUserNamePasswordEventArgs args)
            {
                args.UserName = "user1";
                args.Password = "pass1";
            };

            client.Authentication.SslServerTrustHandlers​ +=
            delegate(object sender, SvnSslServerTrustEventArgs e)
            {
              e.AcceptedFailures = e.Failures;
              e.Save = true; // Save acceptance to authentication store
            };

            SvnCommitArgs ca = new SvnCommitArgs();
            ca.LogMessage = "svn log message created at " + DateTime.Now.ToString();
            bool action = client.Commit(@"C:demo_repodemo_projecttrunkfile.txt", ca);