JGSS: Integrity check on decrypted field failed (31)

[Michael B Allen]

Hi David,

Can you be more specific? The mechToken in the NegTokenInit of the
SPNEGO token is a valid GSSAPI token and is in fact no different from
a raw Kerberos token.

Also, the filter works fine now. I had to initialize the server credential
using the more common method used in the tutorials. It's only on Windows
systems that trying to create a Subject with a KerberosKey from a password
directly that the said error occurs.

My understanding at this point is that it is a flaw in Java's GSSAPI
implementation.

Thanks,
Mike

On Tue, 07 Nov 2006 18:34:46 -0500
David Shambroom <david.shambroom at intersystems.com> wrote:

> What you have is a GSS token using the SPNEGO mechanism that contains a 
> Kerberos AS_REQ message as one of its components.  You need to wrap the 
> extracted Kerberos AS_REQ message in a new GSS token using the Kerberos 
> mechanism before passing it to acceptSecurityContext().  You also need 
> to extract the AS_REP message from the GSS token returned from that call 
> and wrap it in a new GSS token using the SPNEGO mechanism before sending 
> it to the client.  RFCs 1964 and 4121 show how to do this.
> 
> Or, you can use a version of JGSS that understands GSS/SPNEGO as well as 
> GSS/Kerberos.
> 
> --David
> -- 
> W. David Shambroom, Ph.D.
> Security Architect                                          617.551.2143
> InterSystems Corporation                            wds at intersystems.com
> 
> 
> > Message: 2
> > Date: Mon, 6 Nov 2006 14:26:20 -0500 (EST)
> > From: "Michael B Allen" <mba2000 at ioplex.com>
> > Subject: JGSS: Integrity check on decrypted field failed (31)
> > To: kerberos at mit.edu
> > Message-ID: <60406.38.117.185.138.1162841180.squirrel at www.ioplex.com>
> > Content-Type: text/plain;charset=iso-8859-1
> > 
> > I wrote an SPNEGO Java Servlet Filter that decodes the SPNEGO token,
> > plucks out the krb5 mechToken and passes it to acceptSecContext. Works
> > great on Linux/Jetty. Tomcat on Windows gives me the following exception.
> > Basically it looks like it's failing to decrypt the ticket as if the
> > password was wrong (but it's not). The service account is set for DES
> > only. For the service credential, I manually create a KerberosKey with a
> > plaintext password and enctype of "DES".
> > 
> > Before I start doing byte for byte checking can anyone recommend potential
> > reasons for this error?
> > 
> > GSSException: Failure unspecified at GSS-API level (Mechanism level:
> > Integrity check on decrypted field failed (31))
> > 	sun.security.jgss.krb5.Krb5Context.acceptSecContext(Krb5Context.java:734)
> > 	sun.security.jgss.GSSContextImpl.acceptSecContext(GSSContextImpl.java:300)
> > 	sun.security.jgss.GSSContextImpl.acceptSecContext(GSSContextImpl.java:246)
> > 	com.ibi.security.spnego.SpnegoFilter.doFilter(SpnegoFilter.java:262)
> > 
> > 
> ________________________________________________
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> 


-- 
Michael B Allen
PHP Active Directory SSO
http://www.ioplex.com/