JGSS: Integrity check on decrypted field failed (31)

[David Shambroom]

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)
> 
>