Re: incompatibility between Heimdal GSSAPI and MIT GSSAPI foraes256-cts-hmac-sha1-96 credentials?

[Love Hörnquist Åstrand <lha@kth.se>]

Hi Karsten,

> So, the only case which doesn't work is delegating aes256-cts-hmac-sha1-96 
> credentials from MIT to Heimdal. I don't know who's at fault here but maybe 
> someone with a deeper understanding of the protocol than me can have a look.

Can you try this patch ? This was brought to my attention during the last
interop event in Seattle.

Love

--- lib/krb5/rd_cred.c	2005/07/13 20:51:09	1.22.2.1
+++ lib/krb5/rd_cred.c	2005/10/22 02:21:00
@@ -99,13 +99,37 @@ krb5_rd_cred(krb5_context context,
 	enc_krb_cred_part_data.length = cred.enc_part.cipher.length;
 	enc_krb_cred_part_data.data   = cred.enc_part.cipher.data;
     } else {
-	if (auth_context->remote_subkey)
+	/* Try both subkey and session key.
+	 * 
+	 * RFC2140 claims we should use the session key, but Heimdal
+	 * before 0.8 used the remote subkey if it was send in the
+	 * auth_context.
+	 */
+
+	if (auth_context->remote_subkey) {
 	    ret = krb5_crypto_init(context, auth_context->remote_subkey,
 				   0, &crypto);
-	else
+	    if (ret)
+		goto out;
+
+	    ret = krb5_decrypt_EncryptedData(context,
+					     crypto,
+					     KRB5_KU_KRB_CRED,
+					     &cred.enc_part,
+					     &enc_krb_cred_part_data);
+	    
+	    krb5_crypto_destroy(context, crypto);
+	}
+
+	/* 
+	 * If there was not subkey, or we failed using subkey, 
+	 * retry using the session key
+	 */
+	if (auth_context->remote_subkey == NULL || ret == KRB5KRB_AP_ERR_BAD_INTEGRITY)
+	{
+
 	    ret = krb5_crypto_init(context, auth_context->keyblock,
 				   0, &crypto);
-	/* DK: MIT rsh */
 
 	if (ret)
 	    goto out;
@@ -117,6 +141,7 @@ krb5_rd_cred(krb5_context context,
 					 &enc_krb_cred_part_data);
        
 	krb5_crypto_destroy(context, crypto);
+	}
 	if (ret)
 	    goto out;
     }

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