dmake: do not set MAKEFLAGS=k

[unleashed/tickless.git] / usr / src / cmd / krb5 / krb5kdc / kdc_preauth.c

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */


/*
 * kdc/kdc_preauth.c
 *
 * Copyright 1995, 2003 by the Massachusetts Institute of Technology.
 * All Rights Reserved.
 *
 * Export of this software from the United States of America may
 *   require a specific license from the United States Government.
 *   It is the responsibility of any person or organization contemplating
 *   export to obtain such a license before exporting.
 * 
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of M.I.T. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  Furthermore if you modify this software you must label
 * your software as modified software and not distribute it in such a
 * fashion that it might be confused with the original M.I.T. software.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 * 
 * Preauthentication routines for the KDC.
 */

/*
 * Copyright (C) 1998 by the FundsXpress, INC.
 * 
 * All rights reserved.
 * 
 * Export of this software from the United States of America may require
 * a specific license from the United States Government.  It is the
 * responsibility of any person or organization contemplating export to
 * obtain such a license before exporting.
 * 
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of FundsXpress. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  FundsXpress makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include "k5-int.h"
#include "kdc_util.h"
#include "extern.h"
#include "com_err.h"
#include <assert.h>
#include <stdio.h>
#include "adm_proto.h"
#include <libintl.h>
#include <syslog.h>

#include <assert.h>
#include "preauth_plugin.h"

#if TARGET_OS_MAC
static const char *objdirs[] = { KRB5_PLUGIN_BUNDLE_DIR, LIBDIR "/krb5/plugins/preauth", NULL }; /* should be a list */
#else
static const char *objdirs[] = { LIBDIR "/krb5/plugins/preauth", NULL };
#endif

/* XXX This is ugly and should be in a header file somewhere */
#ifndef KRB5INT_DES_TYPES_DEFINED
#define KRB5INT_DES_TYPES_DEFINED
typedef unsigned char des_cblock[8];    /* crypto-block size */
#endif
typedef des_cblock mit_des_cblock;
extern void mit_des_fixup_key_parity (mit_des_cblock );
extern int mit_des_is_weak_key (mit_des_cblock );

typedef struct _krb5_preauth_systems {
    const char *name;
    int         type;
    int         flags;
    void       *plugin_context;
    preauth_server_init_proc    init;
    preauth_server_fini_proc    fini;
    preauth_server_edata_proc   get_edata;
    preauth_server_verify_proc  verify_padata;
    preauth_server_return_proc  return_padata;
    preauth_server_free_reqcontext_proc free_pa_reqctx;
} krb5_preauth_systems;

static krb5_error_code verify_enc_timestamp
    (krb5_context, krb5_db_entry *client,
                    krb5_data *req_pkt,
                    krb5_kdc_req *request,
                    krb5_enc_tkt_part * enc_tkt_reply, krb5_pa_data *data,
                    preauth_get_entry_data_proc get_entry_data,
                    void *pa_system_context,
                    void **pa_request_context,
                    krb5_data **e_data,
                    krb5_authdata ***authz_data);

static krb5_error_code get_etype_info
    (krb5_context, krb5_kdc_req *request,
                    krb5_db_entry *client, krb5_db_entry *server,
                    preauth_get_entry_data_proc get_entry_data,
                    void *pa_system_context,
                    krb5_pa_data *data);
static krb5_error_code
get_etype_info2(krb5_context context, krb5_kdc_req *request,
                krb5_db_entry *client, krb5_db_entry *server,
                preauth_get_entry_data_proc get_entry_data,
                void *pa_system_context,
                krb5_pa_data *pa_data);
static krb5_error_code
etype_info_as_rep_helper(krb5_context context, krb5_pa_data * padata, 
                         krb5_db_entry *client,
                         krb5_kdc_req *request, krb5_kdc_rep *reply,
                         krb5_key_data *client_key,
                         krb5_keyblock *encrypting_key,
                         krb5_pa_data **send_pa,
                         int etype_info2);

static krb5_error_code
return_etype_info(krb5_context, krb5_pa_data * padata, 
                  krb5_db_entry *client,
                  krb5_data *req_pkt,
                  krb5_kdc_req *request, krb5_kdc_rep *reply,
                  krb5_key_data *client_key,
                  krb5_keyblock *encrypting_key,
                  krb5_pa_data **send_pa,
                  preauth_get_entry_data_proc get_entry_data,
                  void *pa_system_context,
                  void **pa_request_context);

static krb5_error_code
return_etype_info2(krb5_context, krb5_pa_data * padata, 
                   krb5_db_entry *client,
                   krb5_data *req_pkt,
                   krb5_kdc_req *request, krb5_kdc_rep *reply,
                   krb5_key_data *client_key,
                   krb5_keyblock *encrypting_key,
                   krb5_pa_data **send_pa,
                   preauth_get_entry_data_proc get_entry_data,
                   void *pa_system_context,
                   void **pa_request_context);

static krb5_error_code return_pw_salt
    (krb5_context, krb5_pa_data * padata, 
                    krb5_db_entry *client,
                    krb5_data *req_pkt,
                    krb5_kdc_req *request, krb5_kdc_rep *reply,
                    krb5_key_data *client_key,
                    krb5_keyblock *encrypting_key,
                    krb5_pa_data **send_pa,
                    preauth_get_entry_data_proc get_entry_data,
                    void *pa_system_context,
                    void **pa_request_context);

/* SAM preauth support */
static krb5_error_code verify_sam_response
    (krb5_context, krb5_db_entry *client,
                    krb5_data *req_pkt,
                    krb5_kdc_req *request,
                    krb5_enc_tkt_part * enc_tkt_reply, krb5_pa_data *data,
                    preauth_get_entry_data_proc get_entry_data,
                    void *pa_module_context,
                    void **pa_request_context,
                    krb5_data **e_data,
                    krb5_authdata ***authz_data);

static krb5_error_code get_sam_edata
    (krb5_context, krb5_kdc_req *request,
                    krb5_db_entry *client, krb5_db_entry *server,
                    preauth_get_entry_data_proc get_entry_data,
                    void *pa_module_context,
                    krb5_pa_data *data);
static krb5_error_code return_sam_data
    (krb5_context, krb5_pa_data * padata, 
                    krb5_db_entry *client,
                    krb5_data *req_pkt,
                    krb5_kdc_req *request, krb5_kdc_rep *reply,
                    krb5_key_data *client_key,
                    krb5_keyblock *encrypting_key,
                    krb5_pa_data **send_pa,
                    preauth_get_entry_data_proc get_entry_data,
                    void *pa_module_context,
                    void **pa_request_context);

static krb5_preauth_systems static_preauth_systems[] = {
    {
        "timestamp",
        KRB5_PADATA_ENC_TIMESTAMP,
        0,
        NULL,
        NULL,
        NULL,
        0,
        verify_enc_timestamp,
        0
    },
    {
        "etype-info",
        KRB5_PADATA_ETYPE_INFO,
        0,
        NULL,
        NULL,
        NULL,
        get_etype_info,
        0,
        return_etype_info
    },
    {
        "etype-info2",
        KRB5_PADATA_ETYPE_INFO2,
        0,
        NULL,
        NULL,
        NULL,
        get_etype_info2,
        0,
        return_etype_info2
    },
    {
        "pw-salt",
        KRB5_PADATA_PW_SALT,
        PA_PSEUDO,              /* Don't include this in the error list */
        NULL,
        NULL,
        NULL,
        0, 
        0,
        return_pw_salt
    },
    {
        "sam-response",
        KRB5_PADATA_SAM_RESPONSE,
        0,
        NULL,
        NULL,
        NULL,
        0,
        verify_sam_response,
        return_sam_data
    },
    {
        "sam-challenge",
        KRB5_PADATA_SAM_CHALLENGE,
        PA_HARDWARE,            /* causes get_preauth_hint_list to use this */
        NULL,
        NULL,
        NULL,
        get_sam_edata,
        0,
        0
    },
    { "[end]", -1,}
};

static krb5_preauth_systems *preauth_systems;
static int n_preauth_systems;
static struct plugin_dir_handle preauth_plugins;

krb5_error_code
load_preauth_plugins(krb5_context context)
{
    struct errinfo err;
    void **preauth_plugins_ftables;
    struct krb5plugin_preauth_server_ftable_v1 *ftable;
    int module_count, i, j, k;
    void *plugin_context;
    preauth_server_init_proc server_init_proc = NULL;
    char **kdc_realm_names = NULL;

    memset(&err, 0, sizeof(err));

    /* Attempt to load all of the preauth plugins we can find. */
    PLUGIN_DIR_INIT(&preauth_plugins);
    if (PLUGIN_DIR_OPEN(&preauth_plugins) == 0) {
        if (krb5int_open_plugin_dirs(objdirs, NULL,
                                     &preauth_plugins, &err) != 0) {
            return KRB5_PLUGIN_NO_HANDLE;
        }
    }

    /* Get the method tables provided by the loaded plugins. */
    preauth_plugins_ftables = NULL;
    if (krb5int_get_plugin_dir_data(&preauth_plugins,
                                    "preauthentication_server_1",
                                    &preauth_plugins_ftables, &err) != 0) {
        return KRB5_PLUGIN_NO_HANDLE;
    }

    /* Count the valid modules. */
    module_count = sizeof(static_preauth_systems)
                   / sizeof(static_preauth_systems[0]);
    if (preauth_plugins_ftables != NULL) {
        for (i = 0; preauth_plugins_ftables[i] != NULL; i++) {
            ftable = preauth_plugins_ftables[i];
            if ((ftable->flags_proc == NULL) &&
                (ftable->edata_proc == NULL) &&
                (ftable->verify_proc == NULL) &&
                (ftable->return_proc == NULL)) {
                continue;
            }
            for (j = 0;
                 ftable->pa_type_list != NULL &&
                 ftable->pa_type_list[j] > 0;
                 j++) {
                module_count++;
            }
        }
    }

    /* Build the complete list of supported preauthentication options, and
     * leave room for a terminator entry. */
    preauth_systems = malloc(sizeof(krb5_preauth_systems) * (module_count + 1));
    if (preauth_systems == NULL) {
        krb5int_free_plugin_dir_data(preauth_plugins_ftables);
        return ENOMEM;
    }

    /* Build a list of the names of the supported realms for this KDC.
     * The list of names is terminated with a NULL. */
    kdc_realm_names = malloc(sizeof(char *) * (kdc_numrealms + 1));
    if (kdc_realm_names == NULL) {
        krb5int_free_plugin_dir_data(preauth_plugins_ftables);
        return ENOMEM;
    }
    for (i = 0; i < kdc_numrealms; i++) {
        kdc_realm_names[i] = kdc_realmlist[i]->realm_name;
    }
    kdc_realm_names[i] = NULL;

    /* Add the locally-supplied mechanisms to the dynamic list first. */
    for (i = 0, k = 0;
         i < sizeof(static_preauth_systems) / sizeof(static_preauth_systems[0]);
         i++) {
        if (static_preauth_systems[i].type == -1)
            break;
        preauth_systems[k] = static_preauth_systems[i];
        /* Try to initialize the preauth system.  If it fails, we'll remove it
         * from the list of systems we'll be using. */
        plugin_context = NULL;
        server_init_proc = static_preauth_systems[i].init;
        if ((server_init_proc != NULL) &&
            ((*server_init_proc)(context, &plugin_context, (const char **)kdc_realm_names) != 0)) {
            memset(&preauth_systems[k], 0, sizeof(preauth_systems[k]));
            continue;
        }
        preauth_systems[k].plugin_context = plugin_context;
        k++;
    }

    /* Now add the dynamically-loaded mechanisms to the list. */
    if (preauth_plugins_ftables != NULL) {
        for (i = 0; preauth_plugins_ftables[i] != NULL; i++) {
            ftable = preauth_plugins_ftables[i];
            if ((ftable->flags_proc == NULL) &&
                (ftable->edata_proc == NULL) &&
                (ftable->verify_proc == NULL) &&
                (ftable->return_proc == NULL)) {
                continue;
            }
            plugin_context = NULL;
            for (j = 0;
                 ftable->pa_type_list != NULL &&
                 ftable->pa_type_list[j] > 0;
                 j++) {
                /* Try to initialize the plugin.  If it fails, we'll remove it
                 * from the list of modules we'll be using. */
                if (j == 0) {
                    server_init_proc = ftable->init_proc;
                    if (server_init_proc != NULL) {
                        krb5_error_code initerr;
                        initerr = (*server_init_proc)(context, &plugin_context, (const char **)kdc_realm_names);
                        if (initerr) {
                            const char *emsg;
                            emsg = krb5_get_error_message(context, initerr);
                            if (emsg) {
                                krb5_klog_syslog(LOG_ERR,
                                        "preauth %s failed to initialize: %s",
                                        ftable->name, emsg);
                                krb5_free_error_message(context, emsg);
                            }
                            memset(&preauth_systems[k], 0, sizeof(preauth_systems[k]));

                            break;      /* skip all modules in this plugin */
                        }
                    }
                }
                preauth_systems[k].name = ftable->name;
                preauth_systems[k].type = ftable->pa_type_list[j];
                if (ftable->flags_proc != NULL)
                    preauth_systems[k].flags = ftable->flags_proc(context, preauth_systems[k].type);
                else
                    preauth_systems[k].flags = 0;
                preauth_systems[k].plugin_context = plugin_context;
                preauth_systems[k].init = server_init_proc;
                /* Only call fini once for each plugin */
                if (j == 0)
                    preauth_systems[k].fini = ftable->fini_proc;
                else
                    preauth_systems[k].fini = NULL;
                preauth_systems[k].get_edata = ftable->edata_proc;
                preauth_systems[k].verify_padata = ftable->verify_proc;
                preauth_systems[k].return_padata = ftable->return_proc;
                preauth_systems[k].free_pa_reqctx =
                    ftable->freepa_reqcontext_proc;
                k++;
            }
        }
        krb5int_free_plugin_dir_data(preauth_plugins_ftables);
    }
    free(kdc_realm_names);
    n_preauth_systems = k;
    /* Add the end-of-list marker. */
    preauth_systems[k].name = "[end]";
    preauth_systems[k].type = -1;
    return 0;
}

krb5_error_code
unload_preauth_plugins(krb5_context context)
{
    int i;
    if (preauth_systems != NULL) {
        for (i = 0; i < n_preauth_systems; i++) {
            if (preauth_systems[i].fini != NULL) {
                (*preauth_systems[i].fini)(context,
                                           preauth_systems[i].plugin_context);
            }
            memset(&preauth_systems[i], 0, sizeof(preauth_systems[i]));
        }
        free(preauth_systems);
        preauth_systems = NULL;
        n_preauth_systems = 0;
        krb5int_close_plugin_dirs(&preauth_plugins);
    }
    return 0;
}

/*
 * The make_padata_context() function creates a space for storing any context
 * information which will be needed by return_padata() later.  Each preauth
 * type gets a context storage location of its own.
 */
struct request_pa_context {
    int n_contexts;
    struct {
        krb5_preauth_systems *pa_system;
        void *pa_context;
    } *contexts;
};

static krb5_error_code
make_padata_context(krb5_context context, void **padata_context)
{
    int i;
    struct request_pa_context *ret;

    ret = malloc(sizeof(*ret));
    if (ret == NULL) {
        return ENOMEM;
    }

    ret->n_contexts = n_preauth_systems;
    ret->contexts = malloc(sizeof(ret->contexts[0]) * ret->n_contexts);
    if (ret->contexts == NULL) {
        free(ret);
        return ENOMEM;
    }

    memset(ret->contexts, 0, sizeof(ret->contexts[0]) * ret->n_contexts);

    for (i = 0; i < ret->n_contexts; i++) {
        ret->contexts[i].pa_system = &preauth_systems[i];
        ret->contexts[i].pa_context = NULL;
    }

    *padata_context = ret;

    return 0;
}

/*
 * The free_padata_context function frees any context information pointers
 * which the check_padata() function created but which weren't already cleaned
 * up by return_padata().
 */
krb5_error_code
free_padata_context(krb5_context kcontext, void **padata_context)
{
    struct request_pa_context *context;
    krb5_preauth_systems *preauth_system;
    void **pctx, *mctx;
    int i;

    if (padata_context == NULL)
        return 0;

    context = *padata_context;

    for (i = 0; i < context->n_contexts; i++) {
        if (context->contexts[i].pa_context != NULL) {
            preauth_system = context->contexts[i].pa_system;
            mctx = preauth_system->plugin_context;
            if (preauth_system->free_pa_reqctx != NULL) {
                pctx = &context->contexts[i].pa_context;
                (*preauth_system->free_pa_reqctx)(kcontext, mctx, pctx);
            }
            context->contexts[i].pa_context = NULL;
        }
    }

    free(context->contexts);
    free(context);

    return 0;
}

/* Retrieve a specified tl_data item from the given entry, and return its
 * contents in a new krb5_data, which must be freed by the caller. */
static krb5_error_code
get_entry_tl_data(krb5_context context, krb5_db_entry *entry,
                  krb5_int16 tl_data_type, krb5_data **result)
{
    krb5_tl_data *tl;
    for (tl = entry->tl_data; tl != NULL; tl = tl->tl_data_next) {
        if (tl->tl_data_type == tl_data_type) {
            *result = malloc(sizeof(krb5_data));
            if (*result == NULL) {
                return ENOMEM;
            }
            (*result)->magic = KV5M_DATA;
            (*result)->data = malloc(tl->tl_data_length);
            if ((*result)->data == NULL) {
                free(*result);
                *result = NULL;
                return ENOMEM;
            }
            memcpy((*result)->data, tl->tl_data_contents, tl->tl_data_length);
            return 0;
        }
    }
    return ENOENT;
}

/*
 * Retrieve a specific piece of information pertaining to the entry or the
 * request and return it in a new krb5_data item which the caller must free.
 *
 * This may require massaging data into a contrived format, but it will
 * hopefully keep us from having to reveal library-internal functions to
 * modules.
 */
static krb5_error_code
get_entry_data(krb5_context context,
               krb5_kdc_req *request, krb5_db_entry *entry,
               krb5_int32  type,
               krb5_data **result)
{
    int i, k;
    krb5_data *ret;
    krb5_deltat *delta;
    krb5_keyblock *keys;
    krb5_key_data *entry_key;

    switch (type) {
    case krb5plugin_preauth_entry_request_certificate:
        return get_entry_tl_data(context, entry,
                                 KRB5_TL_USER_CERTIFICATE, result);
        break;
    case krb5plugin_preauth_entry_max_time_skew:
        ret = malloc(sizeof(krb5_data));
        if (ret == NULL)
            return ENOMEM;
        delta = malloc(sizeof(krb5_deltat));
        if (delta == NULL) {
            free(ret);
            return ENOMEM;
        }
        *delta = context->clockskew;
        ret->data = (char *) delta;
        ret->length = sizeof(*delta);
        *result = ret;
        return 0;
        break;
    case krb5plugin_preauth_keys:
        ret = malloc(sizeof(krb5_data));
        if (ret == NULL)
            return ENOMEM;
        keys = malloc(sizeof(krb5_keyblock) * (request->nktypes + 1));
        if (keys == NULL) {
            free(ret);
            return ENOMEM;
        }
        ret->data = (char *) keys;
        ret->length = sizeof(krb5_keyblock) * (request->nktypes + 1);
        memset(ret->data, 0, ret->length);
        k = 0;
        for (i = 0; i < request->nktypes; i++) {
            entry_key = NULL;
            if (krb5_dbe_find_enctype(context, entry, request->ktype[i],
                                      -1, 0, &entry_key) != 0)
                continue;
            if (krb5_dbekd_decrypt_key_data(context, &master_keyblock,
                                            entry_key, &keys[k], NULL) != 0) {
                if (keys[k].contents != NULL)
                    krb5_free_keyblock_contents(context, &keys[k]);
                memset(&keys[k], 0, sizeof(keys[k]));
                continue;
            }
            k++;
        }
        if (k > 0) {
            *result = ret;
            return 0;
        } else {
            free(keys);
            free(ret);
        }
        break;
    case krb5plugin_preauth_request_body:
        ret = NULL;
        encode_krb5_kdc_req_body(request, &ret);
        if (ret != NULL) {
            *result = ret;
            return 0;
        }
        return ASN1_PARSE_ERROR;
        break;
    default:
        break;
    }
    return ENOENT;
}

static krb5_error_code
find_pa_system(int type, krb5_preauth_systems **preauth)
{
    krb5_preauth_systems *ap;

    ap = preauth_systems ? preauth_systems : static_preauth_systems;
    while ((ap->type != -1) && (ap->type != type))
        ap++;
    if (ap->type == -1)
        return(KRB5_PREAUTH_BAD_TYPE);
    *preauth = ap;
    return 0;
} 

static krb5_error_code
find_pa_context(krb5_preauth_systems *pa_sys,
                struct request_pa_context *context,
                void ***pa_context)
{
    int i;

    *pa_context = 0;

    if (context == NULL)
        return KRB5KRB_ERR_GENERIC;

    for (i = 0; i < context->n_contexts; i++) {
        if (context->contexts[i].pa_system == pa_sys) {
            *pa_context = &context->contexts[i].pa_context;
            return 0;
        }
    }

    return KRB5KRB_ERR_GENERIC;
}

/*
 * Create a list of indices into the preauth_systems array, sorted by order of
 * preference.
 */
static krb5_boolean
pa_list_includes(krb5_pa_data **pa_data, krb5_preauthtype pa_type)
{
    while (*pa_data != NULL) {
        if ((*pa_data)->pa_type == pa_type)
            return TRUE;
        pa_data++;
    }
    return FALSE;
}
static void
sort_pa_order(krb5_context context, krb5_kdc_req *request, int *pa_order)
{
    int i, j, k, n_repliers, n_key_replacers;

    /* First, set up the default order. */
    i = 0;
    for (j = 0; j < n_preauth_systems; j++) {
        if (preauth_systems[j].return_padata != NULL)
            pa_order[i++] = j;
    }
    n_repliers = i;
    pa_order[n_repliers] = -1;

    /* Reorder so that PA_REPLACES_KEY modules are listed first. */
    for (i = 0; i < n_repliers; i++) {
        /* If this module replaces the key, then it's okay to leave it where it
         * is in the order. */
        if (preauth_systems[pa_order[i]].flags & PA_REPLACES_KEY)
            continue;
        /* If not, search for a module which does, and swap in the first one we
         * find. */
        for (j = i + 1; j < n_repliers; j++) {
            if (preauth_systems[pa_order[j]].flags & PA_REPLACES_KEY) {
                k = pa_order[j];
                pa_order[j] = pa_order[i];
                pa_order[i] = k;
                break;
            }
        }
    }

    if (request->padata != NULL) {
        /* Now reorder the subset of modules which replace the key,
         * bubbling those which handle pa_data types provided by the
         * client ahead of the others. */
        for (i = 0; preauth_systems[pa_order[i]].flags & PA_REPLACES_KEY; i++) {
            continue;
        }
        n_key_replacers = i;
        for (i = 0; i < n_key_replacers; i++) {
            if (pa_list_includes(request->padata,
                                preauth_systems[pa_order[i]].type))
                continue;
            for (j = i + 1; j < n_key_replacers; j++) {
                if (pa_list_includes(request->padata,
                                    preauth_systems[pa_order[j]].type)) {
                    k = pa_order[j];
                    pa_order[j] = pa_order[i];
                    pa_order[i] = k;
                    break;
                }
            }
        }
    }
#ifdef DEBUG
    krb5_klog_syslog(LOG_DEBUG, "original preauth mechanism list:");
    for (i = 0; i < n_preauth_systems; i++) {
        if (preauth_systems[i].return_padata != NULL)
            krb5_klog_syslog(LOG_DEBUG, "... %s(%d)", preauth_systems[i].name,
                             preauth_systems[i].type);
    }
    krb5_klog_syslog(LOG_DEBUG, "sorted preauth mechanism list:");
    for (i = 0; pa_order[i] != -1; i++) {
        krb5_klog_syslog(LOG_DEBUG, "... %s(%d)",
                         preauth_systems[pa_order[i]].name,
                         preauth_systems[pa_order[i]].type);
    }
#endif
}

const char *missing_required_preauth(krb5_db_entry *client,
                                     krb5_db_entry *server,
                                     krb5_enc_tkt_part *enc_tkt_reply)
{
#if 0
    /*
     * If this is the pwchange service, and the pre-auth bit is set,
     * allow it even if the HW preauth would normally be required.
     * 
     * Sandia national labs wanted this for some strange reason... we
     * leave it disabled normally.
     */
    if (isflagset(server->attributes, KRB5_KDB_PWCHANGE_SERVICE) &&
        isflagset(enc_tkt_reply->flags, TKT_FLG_PRE_AUTH))
        return 0;
#endif
    
#ifdef DEBUG
    krb5_klog_syslog (LOG_DEBUG,
                      "client needs %spreauth, %shw preauth; request has %spreauth, %shw preauth",
                      isflagset (client->attributes, KRB5_KDB_REQUIRES_PRE_AUTH) ? "" : "no ",
                      isflagset (client->attributes, KRB5_KDB_REQUIRES_HW_AUTH) ? "" : "no ",
                      isflagset (enc_tkt_reply->flags, TKT_FLG_PRE_AUTH) ? "" : "no ",
                      isflagset (enc_tkt_reply->flags, TKT_FLG_HW_AUTH) ? "" : "no ");
#endif

    if (isflagset(client->attributes, KRB5_KDB_REQUIRES_PRE_AUTH) &&
         !isflagset(enc_tkt_reply->flags, TKT_FLG_PRE_AUTH))
        return "NEEDED_PREAUTH";

    if (isflagset(client->attributes, KRB5_KDB_REQUIRES_HW_AUTH) &&
        !isflagset(enc_tkt_reply->flags, TKT_FLG_HW_AUTH))
        return "NEEDED_HW_PREAUTH";

    return 0;
}

void get_preauth_hint_list(krb5_kdc_req *request, krb5_db_entry *client,
                           krb5_db_entry *server, krb5_data *e_data)
{
    int hw_only;
    krb5_preauth_systems *ap;
    krb5_pa_data **pa_data, **pa;
    krb5_data *edat;
    krb5_error_code retval;
    
    /* Zero these out in case we need to abort */
    e_data->length = 0;
    e_data->data = 0;
    
    hw_only = isflagset(client->attributes, KRB5_KDB_REQUIRES_HW_AUTH);
    pa_data = malloc(sizeof(krb5_pa_data *) * (n_preauth_systems+1));
    if (pa_data == 0)
        return;
    memset(pa_data, 0, sizeof(krb5_pa_data *) * (n_preauth_systems+1));
    pa = pa_data;

    for (ap = preauth_systems; ap->type != -1; ap++) {
        if (hw_only && !(ap->flags & PA_HARDWARE))
            continue;
        if (ap->flags & PA_PSEUDO)
            continue;
        *pa = malloc(sizeof(krb5_pa_data));
        if (*pa == 0)
            goto errout;
        memset(*pa, 0, sizeof(krb5_pa_data));
        (*pa)->magic = KV5M_PA_DATA;
        (*pa)->pa_type = ap->type;
        if (ap->get_edata) {
          retval = (ap->get_edata)(kdc_context, request, client, server,
                                   get_entry_data, ap->plugin_context, *pa);
          if (retval) {
            /* just failed on this type, continue */
            free(*pa);
            *pa = 0;
            continue;
          }
        }
        pa++;
    }
    if (pa_data[0] == 0) {
        krb5_klog_syslog (LOG_INFO,
                          "%spreauth required but hint list is empty",
                          hw_only ? "hw" : "");
    }
    retval = encode_krb5_padata_sequence((krb5_pa_data * const *) pa_data,
                                         &edat);
    if (retval)
        goto errout;
    *e_data = *edat;
    free(edat);

errout:
    krb5_free_pa_data(kdc_context, pa_data);
    return;
}

/*
 * Add authorization data returned from preauth modules to the ticket
 * It is assumed that ad is a "null-terminated" array of krb5_authdata ptrs
 */
static krb5_error_code
add_authorization_data(krb5_enc_tkt_part *enc_tkt_part, krb5_authdata **ad)
{
    krb5_authdata **newad;
    int oldones, newones;
    int i;

    if (enc_tkt_part == NULL || ad == NULL)
        return EINVAL;

    for (newones = 0; ad[newones] != NULL; newones++);
    if (newones == 0)
        return 0;   /* nothing to add */

    if (enc_tkt_part->authorization_data == NULL)
        oldones = 0;
    else
        for (oldones = 0;
             enc_tkt_part->authorization_data[oldones] != NULL; oldones++);

    newad = malloc((oldones + newones + 1) * sizeof(krb5_authdata *));
    if (newad == NULL)
        return ENOMEM;

    /* Copy any existing pointers */
    for (i = 0; i < oldones; i++)
        newad[i] = enc_tkt_part->authorization_data[i];

    /* Add the new ones */
    for (i = 0; i < newones; i++)
        newad[oldones+i] = ad[i];

    /* Terminate the new list */
    newad[oldones+i] = NULL;

    /* Free any existing list */
    free(enc_tkt_part->authorization_data);

    /* Install our new list */
    enc_tkt_part->authorization_data = newad;

    return 0;
}

/*
 * This routine is called to verify the preauthentication information
 * for a V5 request.
 *
 * Returns 0 if the pre-authentication is valid, non-zero to indicate
 * an error code of some sort.
 */

krb5_error_code
check_padata (krb5_context context, krb5_db_entry *client, krb5_data *req_pkt,
              krb5_kdc_req *request, krb5_enc_tkt_part *enc_tkt_reply,
              void **padata_context, krb5_data *e_data)
{
    krb5_error_code retval = 0;
    krb5_pa_data **padata;
    krb5_preauth_systems *pa_sys;
    void **pa_context;
    krb5_data *pa_e_data = NULL, *tmp_e_data = NULL;
    int pa_ok = 0, pa_found = 0;
    krb5_error_code saved_retval = 0;
    int use_saved_retval = 0;
    const char *emsg;
    krb5_authdata **tmp_authz_data = NULL;

    if (request->padata == 0)
        return 0;

    if (make_padata_context(context, padata_context) != 0) {
        return KRB5KRB_ERR_GENERIC;
    }

#ifdef DEBUG
    krb5_klog_syslog (LOG_DEBUG, "checking padata");
#endif
    for (padata = request->padata; *padata; padata++) {
#ifdef DEBUG
        krb5_klog_syslog (LOG_DEBUG, ".. pa_type 0x%x", (*padata)->pa_type);
#endif
        if (find_pa_system((*padata)->pa_type, &pa_sys))
            continue;
        if (find_pa_context(pa_sys, *padata_context, &pa_context))
            continue;
#ifdef DEBUG
        krb5_klog_syslog (LOG_DEBUG, ".. pa_type %s", pa_sys->name);
#endif
        if (pa_sys->verify_padata == 0)
            continue;
        pa_found++;
        retval = pa_sys->verify_padata(context, client, req_pkt, request,
                                       enc_tkt_reply, *padata,
                                       get_entry_data, pa_sys->plugin_context,
                                       pa_context, &tmp_e_data, &tmp_authz_data);
        if (retval) {
            emsg = krb5_get_error_message (context, retval);
            krb5_klog_syslog (LOG_INFO, "preauth (%s) verify failure: %s",
                              pa_sys->name, emsg);
            krb5_free_error_message (context, emsg);
            /* Ignore authorization data returned from modules that fail */
            if (tmp_authz_data != NULL) {
                krb5_free_authdata(context, tmp_authz_data);
                tmp_authz_data = NULL;
            }
            if (pa_sys->flags & PA_REQUIRED) {
                /* free up any previous edata we might have been saving */
                if (pa_e_data != NULL)
                    krb5_free_data(context, pa_e_data);
                pa_e_data = tmp_e_data;
                tmp_e_data = NULL;
                use_saved_retval = 0; /* Make sure we use the current retval */
                pa_ok = 0;
                break;
            }
            /*
             * We'll return edata from either the first PA_REQUIRED module
             * that fails, or the first non-PA_REQUIRED module that fails.
             * Hang on to edata from the first non-PA_REQUIRED module.
             * If we've already got one saved, simply discard this one.
             */
            if (tmp_e_data != NULL) {
                if (pa_e_data == NULL) {
                    /* save the first error code and e-data */
                    pa_e_data = tmp_e_data;
                    tmp_e_data = NULL;
                    saved_retval = retval;
                    use_saved_retval = 1;
                } else {
                    /* discard this extra e-data from non-PA_REQUIRED module */
                    krb5_free_data(context, tmp_e_data);
                    tmp_e_data = NULL;
                }
            }
        } else {
#ifdef DEBUG
            krb5_klog_syslog (LOG_DEBUG, ".. .. ok");
#endif
            /* Ignore any edata returned on success */
            if (tmp_e_data != NULL) {
                krb5_free_data(context, tmp_e_data);
                tmp_e_data = NULL;
            }
            /* Add any authorization data to the ticket */
            if (tmp_authz_data != NULL) {
                add_authorization_data(enc_tkt_reply, tmp_authz_data);
                free(tmp_authz_data);
                tmp_authz_data = NULL;
            }
            pa_ok = 1;
            if (pa_sys->flags & PA_SUFFICIENT)
                break;
        }
    }

    /* Don't bother copying and returning e-data on success */
    if (pa_ok && pa_e_data != NULL) {
        krb5_free_data(context, pa_e_data);
        pa_e_data = NULL;
    }
    /* Return any e-data from the preauth that caused us to exit the loop */
    if (pa_e_data != NULL) {
        e_data->data = malloc(pa_e_data->length);
        if (e_data->data == NULL) {
            krb5_free_data(context, pa_e_data);
            /* Solaris Kerberos */
            return ENOMEM;
        }
        memcpy(e_data->data, pa_e_data->data, pa_e_data->length);
        e_data->length = pa_e_data->length;
        krb5_free_data(context, pa_e_data);
        pa_e_data = NULL;
        if (use_saved_retval != 0)
            retval = saved_retval;
    }

    if (pa_ok)
        return 0;

    /* pa system was not found, but principal doesn't require preauth */
    if (!pa_found &&
        !isflagset(client->attributes, KRB5_KDB_REQUIRES_PRE_AUTH) &&
        !isflagset(client->attributes, KRB5_KDB_REQUIRES_HW_AUTH))
       return 0;

    if (!pa_found) {
        emsg = krb5_get_error_message(context, retval);
        krb5_klog_syslog (LOG_INFO, "no valid preauth type found: %s", emsg);
        krb5_free_error_message(context, emsg);
    }
    /* The following switch statement allows us
     * to return some preauth system errors back to the client.
     */
    switch(retval) {
    case KRB5KRB_AP_ERR_BAD_INTEGRITY:
    case KRB5KRB_AP_ERR_SKEW:
    case KRB5KDC_ERR_ETYPE_NOSUPP:
    /* rfc 4556 */
    case KRB5KDC_ERR_CLIENT_NOT_TRUSTED:
    case KRB5KDC_ERR_INVALID_SIG:
    case KRB5KDC_ERR_DH_KEY_PARAMETERS_NOT_ACCEPTED:
    case KRB5KDC_ERR_CANT_VERIFY_CERTIFICATE:
    case KRB5KDC_ERR_INVALID_CERTIFICATE:
    case KRB5KDC_ERR_REVOKED_CERTIFICATE:
    case KRB5KDC_ERR_REVOCATION_STATUS_UNKNOWN:
    case KRB5KDC_ERR_CLIENT_NAME_MISMATCH:
    case KRB5KDC_ERR_INCONSISTENT_KEY_PURPOSE:
    case KRB5KDC_ERR_DIGEST_IN_CERT_NOT_ACCEPTED:
    case KRB5KDC_ERR_PA_CHECKSUM_MUST_BE_INCLUDED:
    case KRB5KDC_ERR_DIGEST_IN_SIGNED_DATA_NOT_ACCEPTED:
    case KRB5KDC_ERR_PUBLIC_KEY_ENCRYPTION_NOT_SUPPORTED:
    /* earlier drafts of what became rfc 4556 */
    case KRB5KDC_ERR_CERTIFICATE_MISMATCH:
    case KRB5KDC_ERR_KDC_NOT_TRUSTED:
    case KRB5KDC_ERR_REVOCATION_STATUS_UNAVAILABLE:
    /* This value is shared with KRB5KDC_ERR_DH_KEY_PARAMETERS_NOT_ACCEPTED. */
    /* case KRB5KDC_ERR_KEY_TOO_WEAK: */
        return retval;
    default:
        return KRB5KDC_ERR_PREAUTH_FAILED;
    }
}

/*
 * return_padata creates any necessary preauthentication
 * structures which should be returned by the KDC to the client
 */
krb5_error_code
return_padata(krb5_context context, krb5_db_entry *client, krb5_data *req_pkt,
              krb5_kdc_req *request, krb5_kdc_rep *reply,
              krb5_key_data *client_key, krb5_keyblock *encrypting_key,
              void **padata_context)
{
    krb5_error_code             retval;
    krb5_pa_data **             padata;
    krb5_pa_data **             send_pa_list;
    krb5_pa_data **             send_pa;
    krb5_pa_data *              pa = 0;
    krb5_preauth_systems *      ap;
    int *                       pa_order;
    int *                       pa_type;
    int                         size = 0;
    void **                     pa_context;
    krb5_boolean                key_modified;
    krb5_keyblock               original_key;
    if ((!*padata_context)&& (make_padata_context(context, padata_context) != 0)) {
        return KRB5KRB_ERR_GENERIC;
    }

    for (ap = preauth_systems; ap->type != -1; ap++) {
        if (ap->return_padata)
            size++;
    }

    if ((send_pa_list = malloc((size+1) * sizeof(krb5_pa_data *))) == NULL)
        return ENOMEM;
    if ((pa_order = malloc((size+1) * sizeof(int))) == NULL) {
        free(send_pa_list);
        return ENOMEM;
    }
    sort_pa_order(context, request, pa_order);

    retval = krb5_copy_keyblock_contents(context, encrypting_key,
                                         &original_key);
    if (retval) {
        free(send_pa_list);
        free(pa_order);
        return retval;
    }
    key_modified = FALSE;

    send_pa = send_pa_list;
    *send_pa = 0;

    for (pa_type = pa_order; *pa_type != -1; pa_type++) {
        ap = &preauth_systems[*pa_type];
        if (!key_modified)
            if (original_key.enctype != encrypting_key->enctype)
                key_modified = TRUE;
        if (!key_modified)
            if (original_key.length != encrypting_key->length)
                key_modified = TRUE;
        if (!key_modified)
            if (memcmp(original_key.contents, encrypting_key->contents,
                       original_key.length) != 0)
                key_modified = TRUE;
        if (key_modified && (ap->flags & PA_REPLACES_KEY))
            continue;
        if (ap->return_padata == 0)
            continue;
        if (find_pa_context(ap, *padata_context, &pa_context))
            continue;
        pa = 0;
        if (request->padata) {
            for (padata = request->padata; *padata; padata++) {
                if ((*padata)->pa_type == ap->type) {
                    pa = *padata;
                    break;
                }
            }
        }
        if ((retval = ap->return_padata(context, pa, client, req_pkt, request, reply,
                                        client_key, encrypting_key, send_pa,
                                        get_entry_data, ap->plugin_context,
                                        pa_context))) {
            goto cleanup;
        }

        if (*send_pa)
            send_pa++;
        *send_pa = 0;
    }
    
    retval = 0;

    if (send_pa_list[0]) {
        reply->padata = send_pa_list;
        send_pa_list = 0;
    }
    
cleanup:
    if (send_pa_list)
        krb5_free_pa_data(context, send_pa_list);

    /* Solaris Kerberos */
    krb5_free_keyblock_contents(context, &original_key);
    free(pa_order);

    return (retval);
}

static krb5_boolean
enctype_requires_etype_info_2(krb5_enctype enctype)
{
    switch(enctype) {
    case ENCTYPE_DES_CBC_CRC:
    case ENCTYPE_DES_CBC_MD4:
    case ENCTYPE_DES_CBC_MD5:
    case ENCTYPE_DES3_CBC_SHA1:
    case ENCTYPE_DES3_CBC_RAW:
    case ENCTYPE_ARCFOUR_HMAC:
    case ENCTYPE_ARCFOUR_HMAC_EXP :
        return 0;
    default:
        if (krb5_c_valid_enctype(enctype))
            return 1;
        else return 0;
    }
}

static krb5_boolean
request_contains_enctype (krb5_context context,  const krb5_kdc_req *request,
                          krb5_enctype enctype)
{
    int i;
    for (i =0; i < request->nktypes; i++)
        if (request->ktype[i] == enctype)
            return 1;
    return 0;
}


static krb5_error_code
verify_enc_timestamp(krb5_context context, krb5_db_entry *client,
                     krb5_data *req_pkt,
                     krb5_kdc_req *request, krb5_enc_tkt_part *enc_tkt_reply,
                     krb5_pa_data *pa,
                     preauth_get_entry_data_proc ets_get_entry_data,
                     void *pa_system_context,
                     void **pa_request_context,
                     krb5_data **e_data,
                     krb5_authdata ***authz_data)
{
    krb5_pa_enc_ts *            pa_enc = 0;
    krb5_error_code             retval;
    krb5_data                   scratch;
    krb5_data                   enc_ts_data;
    krb5_enc_data               *enc_data = 0;
    krb5_keyblock               key;
    krb5_key_data *             client_key;
    krb5_int32                  start;
    krb5_timestamp              timenow;
    krb5_error_code             decrypt_err = 0;

    (void) memset(&key, 0, sizeof(krb5_keyblock));
    scratch.data = (char *) pa->contents;
    scratch.length = pa->length;

    enc_ts_data.data = 0;
    
    if ((retval = decode_krb5_enc_data(&scratch, &enc_data)) != 0)
        goto cleanup;

    enc_ts_data.length = enc_data->ciphertext.length;
    if ((enc_ts_data.data = (char *) malloc(enc_ts_data.length)) == NULL)
        goto cleanup;

    start = 0;
    decrypt_err = 0;
    while (1) {
        if ((retval = krb5_dbe_search_enctype(context, client,
                                              &start, enc_data->enctype,
                                              -1, 0, &client_key)))
            goto cleanup;

        if ((retval = krb5_dbekd_decrypt_key_data(context, &master_keyblock, 
                                                  client_key, &key, NULL)))
            goto cleanup;

        key.enctype = enc_data->enctype;

        retval = krb5_c_decrypt(context, &key, KRB5_KEYUSAGE_AS_REQ_PA_ENC_TS,
                                0, enc_data, &enc_ts_data);
        krb5_free_keyblock_contents(context, &key);
        if (retval == 0)
            break;
        else
            decrypt_err = retval;
    }

    if ((retval = decode_krb5_pa_enc_ts(&enc_ts_data, &pa_enc)) != 0)
        goto cleanup;

    if ((retval = krb5_timeofday(context, &timenow)) != 0)
        goto cleanup;
    
    if (labs(timenow - pa_enc->patimestamp) > context->clockskew) {
        retval = KRB5KRB_AP_ERR_SKEW;
        goto cleanup;
    }

    setflag(enc_tkt_reply->flags, TKT_FLG_PRE_AUTH);

    retval = 0;
    
cleanup:
    if (enc_data) {
        krb5_free_data_contents(context, &enc_data->ciphertext);
        free(enc_data);
    }
    krb5_free_data_contents(context, &enc_ts_data);
    free(pa_enc);
    /*
     * If we get NO_MATCHING_KEY and decryption previously failed, and
     * we failed to find any other keys of the correct enctype after
     * that failed decryption, it probably means that the password was
     * incorrect.
     */
    if (retval == KRB5_KDB_NO_MATCHING_KEY && decrypt_err != 0)
        retval = decrypt_err;
    return retval;
}

static krb5_error_code
_make_etype_info_entry(krb5_context context,
                       krb5_kdc_req *request, krb5_key_data *client_key,
                       krb5_enctype etype, krb5_etype_info_entry **entry,
                       int etype_info2)
{
    krb5_data                   salt;
    krb5_etype_info_entry *     tmp_entry; 
    krb5_error_code             retval;

    if ((tmp_entry = malloc(sizeof(krb5_etype_info_entry))) == NULL)
       return ENOMEM;

    salt.data = 0;

    tmp_entry->magic = KV5M_ETYPE_INFO_ENTRY;
    tmp_entry->etype = etype;
    tmp_entry->length = KRB5_ETYPE_NO_SALT;
    tmp_entry->salt = 0;
    tmp_entry->s2kparams.data = NULL;
    tmp_entry->s2kparams.length = 0;
    retval = get_salt_from_key(context, request->client,
                               client_key, &salt);
    if (retval)
        goto fail;
    if (etype_info2 && client_key->key_data_ver > 1 &&
        client_key->key_data_type[1] == KRB5_KDB_SALTTYPE_AFS3) {
        switch (etype) {
        case ENCTYPE_DES_CBC_CRC:
        case ENCTYPE_DES_CBC_MD4:
        case ENCTYPE_DES_CBC_MD5:
            tmp_entry->s2kparams.data = malloc(1);
            if (tmp_entry->s2kparams.data == NULL) {
                retval = ENOMEM;
                goto fail;
            }
            tmp_entry->s2kparams.length = 1;
            tmp_entry->s2kparams.data[0] = 1;
            break;
        default:
            break;
        }
    }

    if (salt.length >= 0) {
        tmp_entry->length = salt.length;
        tmp_entry->salt = (unsigned char *) salt.data;
        salt.data = 0;
    }
    *entry = tmp_entry;
    return 0;

fail:
    if (tmp_entry) {
        free(tmp_entry->s2kparams.data);
        free(tmp_entry);
    }
    free(salt.data);
    return retval;
}
/*
 * This function returns the etype information for a particular
 * client, to be passed back in the preauth list in the KRB_ERROR
 * message.  It supports generating both etype_info  and etype_info2
 *  as most of the work is the same.   
 */
static krb5_error_code
etype_info_helper(krb5_context context, krb5_kdc_req *request,
               krb5_db_entry *client, krb5_db_entry *server,
               krb5_pa_data *pa_data, int etype_info2)
{
    krb5_etype_info_entry **    entry = 0;
    krb5_key_data               *client_key;
    krb5_error_code             retval;
    krb5_data *                 scratch;
    krb5_enctype                db_etype;
    int                         i = 0;
    int                         start = 0;
    int                         seen_des = 0;

    entry = malloc((client->n_key_data * 2 + 1) * sizeof(krb5_etype_info_entry *));
    if (entry == NULL)
        return ENOMEM;
    entry[0] = NULL;

    while (1) {
        retval = krb5_dbe_search_enctype(context, client, &start, -1,
                                         -1, 0, &client_key);
        if (retval == KRB5_KDB_NO_MATCHING_KEY)
            break;
        if (retval)
            goto cleanup;
        db_etype = client_key->key_data_type[0];
        if (db_etype == ENCTYPE_DES_CBC_MD4)
            db_etype = ENCTYPE_DES_CBC_MD5;
        
        if (request_contains_enctype(context, request, db_etype)) {
            assert(etype_info2 ||
                   !enctype_requires_etype_info_2(db_etype));
            if ((retval = _make_etype_info_entry(context, request, client_key,
                            db_etype, &entry[i], etype_info2)) != 0) {
                goto cleanup;
            }
            entry[i+1] = 0;
            i++;
        }

        /* 
         * If there is a des key in the kdb, try the "similar" enctypes,
         * avoid duplicate entries. 
         */
        if (!seen_des) {
            switch (db_etype) {
            case ENCTYPE_DES_CBC_MD5:
                db_etype = ENCTYPE_DES_CBC_CRC;
                break;
            case ENCTYPE_DES_CBC_CRC:
                db_etype = ENCTYPE_DES_CBC_MD5;
                break;
            default:
                continue;

            }
            if (request_contains_enctype(context, request, db_etype)) {
                if ((retval = _make_etype_info_entry(context, request,
                                client_key, db_etype, &entry[i], etype_info2)) != 0) {
                    goto cleanup;
                }
                entry[i+1] = 0;
                i++;
            }
            seen_des++;
        }
    }
    if (etype_info2)
        retval = encode_krb5_etype_info2((krb5_etype_info_entry * const*) entry,
                                    &scratch);
    else        retval = encode_krb5_etype_info((krb5_etype_info_entry * const*) entry,
                                    &scratch);
    if (retval)
        goto cleanup;
    pa_data->contents = (unsigned char *)scratch->data;
    pa_data->length = scratch->length;
    free(scratch);

    retval = 0;

cleanup:
    if (entry)
        krb5_free_etype_info(context, entry);
    return retval;
}

static krb5_error_code
get_etype_info(krb5_context context, krb5_kdc_req *request,
               krb5_db_entry *client, krb5_db_entry *server,
               preauth_get_entry_data_proc etype_get_entry_data,
               void *pa_system_context,
               krb5_pa_data *pa_data)
{
  int i;
    for (i=0;  i < request->nktypes; i++) {
        if (enctype_requires_etype_info_2(request->ktype[i])) 
            return KRB5KDC_ERR_PADATA_TYPE_NOSUPP ;;;; /*Caller will
                                                        * skip this
                                                        * type*/
    }
    return etype_info_helper(context, request, client, server, pa_data, 0);
}

static krb5_error_code
get_etype_info2(krb5_context context, krb5_kdc_req *request,
               krb5_db_entry *client, krb5_db_entry *server,
               preauth_get_entry_data_proc etype_get_entry_data,
               void *pa_system_context,
               krb5_pa_data *pa_data)
{
    return etype_info_helper( context, request, client, server, pa_data, 1);
}

static krb5_error_code
etype_info_as_rep_helper(krb5_context context, krb5_pa_data * padata, 
                         krb5_db_entry *client,
                         krb5_kdc_req *request, krb5_kdc_rep *reply,
                         krb5_key_data *client_key,
                         krb5_keyblock *encrypting_key,
                         krb5_pa_data **send_pa,
                         int etype_info2)
{
    int i;
    krb5_error_code retval;
    krb5_pa_data *tmp_padata;
    krb5_etype_info_entry **entry = NULL;
    krb5_data *scratch = NULL;

    /*
     * Skip PA-ETYPE-INFO completely if AS-REQ lists any "newer"
     * enctypes.
     */
    if (!etype_info2) {
        for (i = 0; i < request->nktypes; i++) {
            if (enctype_requires_etype_info_2(request->ktype[i])) {
                *send_pa = NULL;
                return 0;
            }
        }
    }

    tmp_padata = malloc( sizeof(krb5_pa_data));
    if (tmp_padata == NULL)
        return ENOMEM;
    if (etype_info2)
        tmp_padata->pa_type = KRB5_PADATA_ETYPE_INFO2;
    else
        tmp_padata->pa_type = KRB5_PADATA_ETYPE_INFO;

    entry = malloc(2 * sizeof(krb5_etype_info_entry *));
    if (entry == NULL) {
        retval = ENOMEM;
        goto cleanup;
    }
    entry[0] = NULL;
    entry[1] = NULL;
    retval = _make_etype_info_entry(context, request,
                                    client_key, encrypting_key->enctype,
                                    entry, etype_info2);
    if (retval)
        goto cleanup;

    if (etype_info2)
        retval = encode_krb5_etype_info2((krb5_etype_info_entry * const*) entry, &scratch);
    else
        retval = encode_krb5_etype_info((krb5_etype_info_entry * const*) entry, &scratch);

    if (retval)
        goto cleanup;
    tmp_padata->contents = (uchar_t *)scratch->data;
    tmp_padata->length = scratch->length;
    *send_pa = tmp_padata;

    /* For cleanup - we no longer own the contents of the krb5_data 
     * only to pointer to the krb5_data
     */
    scratch->data = 0;

 cleanup:
    if (entry)
        krb5_free_etype_info(context, entry);
    if (retval) {
        free(tmp_padata);
    }
    if (scratch)
            krb5_free_data(context, scratch);
    return retval;
}

static krb5_error_code
return_etype_info2(krb5_context context, krb5_pa_data * padata, 
                   krb5_db_entry *client,
                   krb5_data *req_pkt,
                   krb5_kdc_req *request, krb5_kdc_rep *reply,
                   krb5_key_data *client_key,
                   krb5_keyblock *encrypting_key,
                   krb5_pa_data **send_pa,
                   preauth_get_entry_data_proc etype_get_entry_data,
                   void *pa_system_context,
                   void **pa_request_context)
{
    return etype_info_as_rep_helper(context, padata, client, request, reply,
                                    client_key, encrypting_key, send_pa, 1);
}


static krb5_error_code
return_etype_info(krb5_context context, krb5_pa_data * padata, 
                  krb5_db_entry *client,
                  krb5_data *req_pkt,
                  krb5_kdc_req *request, krb5_kdc_rep *reply,
                  krb5_key_data *client_key,
                  krb5_keyblock *encrypting_key,
                  krb5_pa_data **send_pa,
                  preauth_get_entry_data_proc etypeget_entry_data,
                  void *pa_system_context,
                  void **pa_request_context)
{
    return etype_info_as_rep_helper(context, padata, client, request, reply,
                                    client_key, encrypting_key, send_pa, 0);
}

static krb5_error_code
return_pw_salt(krb5_context context, krb5_pa_data *in_padata,
               krb5_db_entry *client, krb5_data *req_pkt, krb5_kdc_req *request,
               krb5_kdc_rep *reply, krb5_key_data *client_key,
               krb5_keyblock *encrypting_key, krb5_pa_data **send_pa,
               preauth_get_entry_data_proc etype_get_entry_data,
               void *pa_system_context,
               void **pa_request_context)
{
    krb5_error_code     retval;
    krb5_pa_data *      padata;
    krb5_data *         scratch;
    krb5_data           salt_data;
    int i;
    
    for (i = 0; i < request->nktypes; i++) {
        if (enctype_requires_etype_info_2(request->ktype[i]))
            return 0;
    }
    if (client_key->key_data_ver == 1 ||
        client_key->key_data_type[1] == KRB5_KDB_SALTTYPE_NORMAL)
        return 0;

    if ((padata = malloc(sizeof(krb5_pa_data))) == NULL)
        return ENOMEM;
    padata->magic = KV5M_PA_DATA;
    padata->pa_type = KRB5_PADATA_PW_SALT;
    
    switch (client_key->key_data_type[1]) {
    case KRB5_KDB_SALTTYPE_V4:
        /* send an empty (V4) salt */
        padata->contents = 0;
        padata->length = 0;
        break;
    case KRB5_KDB_SALTTYPE_NOREALM:
        if ((retval = krb5_principal2salt_norealm(kdc_context, 
                                                   request->client,
                                                   &salt_data)))
            goto cleanup;
        padata->contents = (krb5_octet *)salt_data.data;
        padata->length = salt_data.length;
        break;
    case KRB5_KDB_SALTTYPE_AFS3:
        /* send an AFS style realm-based salt */
        /* for now, just pass the realm back and let the client
           do the work. In the future, add a kdc configuration
           variable that specifies the old cell name. */
        padata->pa_type = KRB5_PADATA_AFS3_SALT;
        /* it would be just like ONLYREALM, but we need to pass the 0 */
        scratch = krb5_princ_realm(kdc_context, request->client);
        if ((padata->contents = malloc(scratch->length+1)) == NULL) {
            retval = ENOMEM;
            goto cleanup;
        }
        memcpy(padata->contents, scratch->data, scratch->length);
        padata->length = scratch->length+1;
        padata->contents[scratch->length] = 0;
        break;
    case KRB5_KDB_SALTTYPE_ONLYREALM:
        scratch = krb5_princ_realm(kdc_context, request->client);
        if ((padata->contents = malloc(scratch->length)) == NULL) {
            retval = ENOMEM;
            goto cleanup;
        }
        memcpy(padata->contents, scratch->data, scratch->length);
        padata->length = scratch->length;
        break;
    case KRB5_KDB_SALTTYPE_SPECIAL:
        if ((padata->contents = malloc(client_key->key_data_length[1]))
            == NULL) {
            retval = ENOMEM;
            goto cleanup;
        }
        memcpy(padata->contents, client_key->key_data_contents[1],
               client_key->key_data_length[1]);
        padata->length = client_key->key_data_length[1];
        break;
    default:
        free(padata);
        return 0;
    }

    *send_pa = padata;
    return 0;
    
cleanup:
    free(padata);
    return retval;
}

static krb5_error_code
return_sam_data(krb5_context context, krb5_pa_data *in_padata,
                krb5_db_entry *client, krb5_data *req_pkt, krb5_kdc_req *request,
                krb5_kdc_rep *reply, krb5_key_data *client_key,
                krb5_keyblock *encrypting_key, krb5_pa_data **send_pa,
                preauth_get_entry_data_proc sam_get_entry_data,
                void *pa_system_context,
                void **pa_request_context)
{
    krb5_error_code     retval;
    krb5_data           scratch;
    int                 i;

    krb5_sam_response           *sr = 0;
    krb5_predicted_sam_response *psr = 0;

    if (in_padata == 0)
        return 0;

    /*
     * We start by doing the same thing verify_sam_response() does:
     * extract the psr from the padata (which is an sr). Nothing
     * here should generate errors! We've already successfully done
     * all this once.
     */

    scratch.data = (char *) in_padata->contents; /* SUNWresync121 XXX */
    scratch.length = in_padata->length;
    
    if ((retval = decode_krb5_sam_response(&scratch, &sr))) {
        com_err("krb5kdc", retval,
                gettext("return_sam_data(): decode_krb5_sam_response failed"));
        goto cleanup;
    }

    {
        krb5_enc_data tmpdata;

        tmpdata.enctype = ENCTYPE_UNKNOWN;
        tmpdata.ciphertext = sr->sam_track_id;

        scratch.length = tmpdata.ciphertext.length;
        if ((scratch.data = (char *) malloc(scratch.length)) == NULL) {
            retval = ENOMEM;
            goto cleanup;
        }

        if ((retval = krb5_c_decrypt(context, &psr_key, /* XXX */ 0, 0,
                                     &tmpdata, &scratch))) {
            com_err("krb5kdc", retval,
                    gettext("return_sam_data(): decrypt track_id failed"));
            free(scratch.data);
            goto cleanup;
        }
    }

    if ((retval = decode_krb5_predicted_sam_response(&scratch, &psr))) {
        com_err("krb5kdc", retval,
                gettext(
                "return_sam_data(): decode_krb5_predicted_sam_response failed"));
        free(scratch.data);
        goto cleanup;
    }

    /* We could use sr->sam_flags, but it may be absent or altered. */
    if (psr->sam_flags & KRB5_SAM_MUST_PK_ENCRYPT_SAD) {
        com_err("krb5kdc", retval = KRB5KDC_ERR_PREAUTH_FAILED,
                gettext("Unsupported SAM flag must-pk-encrypt-sad"));
        goto cleanup;
    }
    if (psr->sam_flags & KRB5_SAM_SEND_ENCRYPTED_SAD) {
        /* No key munging */
        goto cleanup;
    }
    if (psr->sam_flags & KRB5_SAM_USE_SAD_AS_KEY) {
        /* Use sam_key instead of client key */
        krb5_free_keyblock_contents(context, encrypting_key);
        krb5_copy_keyblock_contents(context, &psr->sam_key, encrypting_key);
        /* XXX Attach a useful pa_data */
        goto cleanup;
    }

    /* Otherwise (no flags set), we XOR the keys */
    /* XXX The passwords-04 draft is underspecified here wrt different
           key types. We will do what I hope to get into the -05 draft. */
    {
        krb5_octet *p = encrypting_key->contents;
        krb5_octet *q = psr->sam_key.contents;
        int length = ((encrypting_key->length < psr->sam_key.length)
                      ? encrypting_key->length
                      : psr->sam_key.length);

        for (i = 0; i < length; i++)
            p[i] ^= q[i];
    }

    /* Post-mixing key correction */
    switch (encrypting_key->enctype) {
    case ENCTYPE_DES_CBC_CRC:
    case ENCTYPE_DES_CBC_MD4:
    case ENCTYPE_DES_CBC_MD5:
    case ENCTYPE_DES_CBC_RAW:
        mit_des_fixup_key_parity(encrypting_key->contents);
        if (mit_des_is_weak_key(encrypting_key->contents))
            ((krb5_octet *) encrypting_key->contents)[7] ^= 0xf0;
        break;

    /* XXX case ENCTYPE_DES3_CBC_MD5: listed in 1510bis-04 draft */
    case ENCTYPE_DES3_CBC_SHA: /* XXX deprecated? */
    case ENCTYPE_DES3_CBC_RAW:
    case ENCTYPE_DES3_CBC_SHA1:
        for (i = 0; i < 3; i++) {
            mit_des_fixup_key_parity(encrypting_key->contents + i * 8);
            if (mit_des_is_weak_key(encrypting_key->contents + i * 8))
                ((krb5_octet *) encrypting_key->contents)[7 + i * 8] ^= 0xf0;
        }
        break;

    default:
        com_err("krb5kdc", retval = KRB5KDC_ERR_PREAUTH_FAILED,
                gettext("Unimplemented keytype for SAM key mixing"));
        goto cleanup;
    }

    /* XXX Attach a useful pa_data */
cleanup:
    if (sr)
        krb5_free_sam_response(context, sr);
    if (psr)
        krb5_free_predicted_sam_response(context, psr);

    return retval;
}
    
static struct {
  char* name;
  int   sam_type;
} *sam_ptr, sam_inst_map[] = {
#if 0   /* SUNWresync121 - unsupported hardware and kdc.log annoyance */
  { "SNK4", PA_SAM_TYPE_DIGI_PATH, },
  { "SECURID", PA_SAM_TYPE_SECURID, },
  { "GRAIL", PA_SAM_TYPE_GRAIL, },
#endif
  { 0, 0 },
};

static krb5_error_code
get_sam_edata(krb5_context context, krb5_kdc_req *request,
              krb5_db_entry *client, krb5_db_entry *server,
              preauth_get_entry_data_proc sam_get_entry_data,
              void *pa_system_context, krb5_pa_data *pa_data)
{
    krb5_error_code             retval;
    krb5_sam_challenge          sc;
    krb5_predicted_sam_response psr;
    krb5_data *                 scratch;
    krb5_keyblock encrypting_key;
    char response[9];
    char inputblock[8];
    krb5_data predict_response;

    (void) memset(&encrypting_key, 0, sizeof(krb5_keyblock));
    (void) memset(&sc, 0, sizeof(sc));
    (void) memset(&psr, 0, sizeof(psr));

    /* Given the client name we can figure out what type of preauth
       they need. The spec is currently for querying the database for
       names that match the types of preauth used. Later we should
       make this mapping show up in kdc.conf. In the meantime, we
       hardcode the following:
                /SNK4 -- Digital Pathways SNK/4 preauth.
                /GRAIL -- experimental preauth
       The first one found is used. See sam_inst_map above.

       For SNK4 in particular, the key in the database is the key for
       the device; kadmin needs a special interface for it.
     */

    {
      int npr = 1;
      krb5_boolean more;
      krb5_db_entry assoc;
      krb5_key_data  *assoc_key;
      krb5_principal newp;
      int probeslot;

      sc.sam_type = 0;

      retval = krb5_copy_principal(kdc_context, request->client, &newp);
      if (retval) {
        com_err(gettext("krb5kdc"),
                retval,
                gettext("copying client name for preauth probe"));
        return retval;
      }

      probeslot = krb5_princ_size(context, newp)++;
      krb5_princ_name(kdc_context, newp) = 
        reallocarray(krb5_princ_name(kdc_context, newp),
                     krb5_princ_size(context, newp), sizeof(krb5_data));

      for(sam_ptr = sam_inst_map; sam_ptr->name; sam_ptr++) {
        krb5_princ_component(kdc_context,newp,probeslot)->data = sam_ptr->name;
        krb5_princ_component(kdc_context,newp,probeslot)->length = 
          strlen(sam_ptr->name);
        npr = 1;
        retval = krb5_db_get_principal(kdc_context, newp, &assoc, &npr, (uint *)&more);
        if(!retval && npr) {
          sc.sam_type = sam_ptr->sam_type;
          break;
        }
      }

      krb5_princ_component(kdc_context,newp,probeslot)->data = 0;
      krb5_princ_component(kdc_context,newp,probeslot)->length = 0;
      krb5_princ_size(context, newp)--;

      krb5_free_principal(kdc_context, newp);

      /* if sc.sam_type is set, it worked */
      if (sc.sam_type) {
        /* so use assoc to get the key out! */
        {
          /* here's what do_tgs_req does */
          retval = krb5_dbe_find_enctype(kdc_context, &assoc,
                                         ENCTYPE_DES_CBC_RAW,
                                         KRB5_KDB_SALTTYPE_NORMAL,
                                         0,             /* Get highest kvno */
                                         &assoc_key);
          if (retval) {
            char *sname;
            krb5_unparse_name(kdc_context, request->client, &sname);
            com_err(gettext("krb5kdc"), 
                    retval, 
                    gettext("snk4 finding the enctype and key <%s>"),
                    sname);
            free(sname);
            return retval;
          }
          /* convert server.key into a real key */
          retval = krb5_dbekd_decrypt_key_data(kdc_context,
                                               &master_keyblock, 
                                               assoc_key, &encrypting_key,
                                               NULL);
          if (retval) {
            com_err(gettext("krb5kdc"),
                    retval, 
                   gettext("snk4 pulling out key entry"));
            return retval;
          }
          /* now we can use encrypting_key... */
        }
      } else {
        /* SAM is not an option - so don't return as hint */
        return KRB5_PREAUTH_BAD_TYPE;
      }
    }
    sc.magic = KV5M_SAM_CHALLENGE;
    psr.sam_flags = sc.sam_flags = KRB5_SAM_USE_SAD_AS_KEY;

    /* Replay prevention */
    if ((retval = krb5_copy_principal(context, request->client, &psr.client)))
        return retval;
#ifdef USE_RCACHE
    if ((retval = krb5_us_timeofday(context, &psr.stime, &psr.susec)))
        return retval;
#endif /* USE_RCACHE */

    switch (sc.sam_type) {
    case PA_SAM_TYPE_GRAIL:
      sc.sam_type_name.data = "Experimental System";
      sc.sam_type_name.length = strlen(sc.sam_type_name.data);
      sc.sam_challenge_label.data = "experimental challenge label";
      sc.sam_challenge_label.length = strlen(sc.sam_challenge_label.data);
      sc.sam_challenge.data = "12345";
      sc.sam_challenge.length = strlen(sc.sam_challenge.data);

#if 0 /* Enable this to test "normal" (no flags set) mode.  */
      psr.sam_flags = sc.sam_flags = 0;
#endif

      psr.magic = KV5M_PREDICTED_SAM_RESPONSE;
      /* string2key on sc.sam_challenge goes in here */
      /* eblock is just to set the enctype */
      {
        const krb5_enctype type = ENCTYPE_DES_CBC_MD5;

        if ((retval = krb5_c_string_to_key(context, type, &sc.sam_challenge,
                                           0 /* salt */, &psr.sam_key)))
            goto cleanup;

        if ((retval = encode_krb5_predicted_sam_response(&psr, &scratch)))
            goto cleanup;
        
        {
            size_t enclen;
            krb5_enc_data tmpdata;

            if ((retval = krb5_c_encrypt_length(context,
                                                psr_key.enctype,
                                                scratch->length, &enclen)))
                goto cleanup;

            if ((tmpdata.ciphertext.data = (char *) malloc(enclen)) == NULL) {
                retval = ENOMEM;
                goto cleanup;
            }
            tmpdata.ciphertext.length = enclen;

            if ((retval = krb5_c_encrypt(context, &psr_key,
                                         /* XXX */ 0, 0, scratch, &tmpdata)))
                goto cleanup;

            sc.sam_track_id = tmpdata.ciphertext;
        }
      }

      sc.sam_response_prompt.data = "response prompt";
      sc.sam_response_prompt.length = strlen(sc.sam_response_prompt.data);
      sc.sam_pk_for_sad.length = 0;
      sc.sam_nonce = 0;
      /* Generate checksum */
      /*krb5_checksum_size(context, ctype)*/
      /*krb5_calculate_checksum(context,ctype,in,in_length,seed,
        seed_length,outcksum) */
      /*krb5_verify_checksum(context,ctype,cksum,in,in_length,seed,
        seed_length) */
#if 0 /* XXX a) glue appears broken; b) this gives up the SAD */
      sc.sam_cksum.contents = (krb5_octet *)
        malloc(krb5_checksum_size(context, CKSUMTYPE_RSA_MD5_DES));
      if (sc.sam_cksum.contents == NULL) return(ENOMEM);

      retval = krb5_calculate_checksum(context, CKSUMTYPE_RSA_MD5_DES,
                                       sc.sam_challenge.data,
                                       sc.sam_challenge.length,
                                       psr.sam_key.contents, /* key */
                                       psr.sam_key.length, /* key length */
                                       &sc.sam_cksum);
      if (retval) { free(sc.sam_cksum.contents); return(retval); }
#endif /* 0 */
      
      retval = encode_krb5_sam_challenge(&sc, &scratch);
      if (retval) goto cleanup;
      pa_data->magic = KV5M_PA_DATA;
      pa_data->pa_type = KRB5_PADATA_SAM_CHALLENGE;
      pa_data->contents = (unsigned char *) scratch->data;
      pa_data->length = scratch->length;
      
      retval = 0;
      break;
    case PA_SAM_TYPE_DIGI_PATH:
      sc.sam_type_name.data = "Digital Pathways";
      sc.sam_type_name.length = strlen(sc.sam_type_name.data);
#if 1
      sc.sam_challenge_label.data = "Enter the following on your keypad";
      sc.sam_challenge_label.length = strlen(sc.sam_challenge_label.data);
#endif
      /* generate digit string, take it mod 1000000 (six digits.) */
      {
        int j;
        krb5_keyblock session_key;
        char outputblock[8];
        int i;

        (void) memset(&session_key, 0, sizeof(krb5_keyblock));

        (void) memset(inputblock, 0, 8);

        retval = krb5_c_make_random_key(kdc_context, ENCTYPE_DES_CBC_CRC,
                                        &session_key);

        if (retval) {
          /* random key failed */
          com_err(gettext("krb5kdc"),
                 retval,
                gettext("generating random challenge for preauth"));
          return retval;
        }
        /* now session_key has a key which we can pick bits out of */
        /* we need six decimal digits. Grab 6 bytes, div 2, mod 10 each. */
        if (session_key.length != 8) {
                 retval = KRB5KDC_ERR_ETYPE_NOSUPP,
          com_err(gettext("krb5kdc"),
                 retval = KRB5KDC_ERR_ETYPE_NOSUPP,
                 gettext("keytype didn't match code expectations"));
          return retval;
        }
        for(i = 0; i<6; i++) {
          inputblock[i] = '0' + ((session_key.contents[i]/2) % 10);
        }
        if (session_key.contents)
          krb5_free_keyblock_contents(kdc_context, &session_key);

        /* retval = krb5_finish_key(kdc_context, &eblock); */
        /* now we have inputblock containing the 8 byte input to DES... */
        sc.sam_challenge.data = inputblock;
        sc.sam_challenge.length = 6;

        encrypting_key.enctype = ENCTYPE_DES_CBC_RAW;

        if (retval) {
          com_err(gettext("krb5kdc"),
                 retval,
                gettext("snk4 processing key"));
        }

        {
            krb5_data plain;
            krb5_enc_data cipher;

            plain.length = 8;
            plain.data = inputblock;

            /* XXX I know this is enough because of the fixed raw enctype.
               if it's not, the underlying code will return a reasonable
               error, which should never happen */
            cipher.ciphertext.length = 8;
            cipher.ciphertext.data = outputblock;

            if ((retval = krb5_c_encrypt(kdc_context, &encrypting_key,
                                         /* XXX */ 0, 0, &plain, &cipher))) {
                com_err(gettext("krb5kdc"), 
                retval, 
                gettext("snk4 response generation failed"));
                return retval;
            }
        }

        /* now output block is the raw bits of the response; convert it
           to display form */
        for (j=0; j<4; j++) {
          char n[2];
          int k;
          n[0] = outputblock[j] & 0xf;
          n[1] = (outputblock[j]>>4) & 0xf;
          for (k=0; k<2; k++) {
            if(n[k] > 9) n[k] = ((n[k]-1)>>2);
            /* This is equivalent to:
               if(n[k]>=0xa && n[k]<=0xc) n[k] = 2;
               if(n[k]>=0xd && n[k]<=0xf) n[k] = 3;
               */
          }
          /* for v4, we keygen: *(j+(char*)&key1) = (n[1]<<4) | n[0]; */
          /* for v5, we just generate a string */
          response[2*j+0] = '0' + n[1];
          response[2*j+1] = '0' + n[0];
          /* and now, response has what we work with. */
        }
        response[8] = 0;
        predict_response.data = response;
        predict_response.length = 8;
#if 0                           /* for debugging, hack the output too! */
sc.sam_challenge_label.data = response;
sc.sam_challenge_label.length = strlen(sc.sam_challenge_label.data);
#endif
      }

      psr.magic = KV5M_PREDICTED_SAM_RESPONSE;
      /* string2key on sc.sam_challenge goes in here */
      /* eblock is just to set the enctype */
      {
        retval = krb5_c_string_to_key(context, ENCTYPE_DES_CBC_MD5,
                                      &predict_response, 0 /* salt */,
                                      &psr.sam_key);
        if (retval) goto cleanup;

        retval = encode_krb5_predicted_sam_response(&psr, &scratch);
        if (retval) goto cleanup;
        
        {
            size_t enclen;
            krb5_enc_data tmpdata;

            if ((retval = krb5_c_encrypt_length(context,
                                                psr_key.enctype,
                                                scratch->length, &enclen)))
                goto cleanup;

            if ((tmpdata.ciphertext.data = (char *) malloc(enclen)) == NULL) {
                retval = ENOMEM;
                goto cleanup;
            }
            tmpdata.ciphertext.length = enclen;

            if ((retval = krb5_c_encrypt(context, &psr_key,
                                         /* XXX */ 0, 0, scratch, &tmpdata)))
                goto cleanup;

            sc.sam_track_id = tmpdata.ciphertext;
        }
        if (retval) goto cleanup;
      }

      sc.sam_response_prompt.data = "Enter the displayed response";
      sc.sam_response_prompt.length = strlen(sc.sam_response_prompt.data);
      sc.sam_pk_for_sad.length = 0;
      sc.sam_nonce = 0;
      /* Generate checksum */
      /*krb5_checksum_size(context, ctype)*/
      /*krb5_calculate_checksum(context,ctype,in,in_length,seed,
        seed_length,outcksum) */
      /*krb5_verify_checksum(context,ctype,cksum,in,in_length,seed,
        seed_length) */
#if 0 /* XXX a) glue appears broken; b) this gives up the SAD */
      sc.sam_cksum.contents = (krb5_octet *)
        malloc(krb5_checksum_size(context, CKSUMTYPE_RSA_MD5_DES));
      if (sc.sam_cksum.contents == NULL) return(ENOMEM);

      retval = krb5_calculate_checksum(context, CKSUMTYPE_RSA_MD5_DES,
                                       sc.sam_challenge.data,
                                       sc.sam_challenge.length,
                                       psr.sam_key.contents, /* key */
                                       psr.sam_key.length, /* key length */
                                       &sc.sam_cksum);
      if (retval) { free(sc.sam_cksum.contents); return(retval); }
#endif /* 0 */
      
      retval = encode_krb5_sam_challenge(&sc, &scratch);
      if (retval) goto cleanup;
      pa_data->magic = KV5M_PA_DATA;
      pa_data->pa_type = KRB5_PADATA_SAM_CHALLENGE;
      pa_data->contents = (unsigned char *) scratch->data;
      pa_data->length = scratch->length;
      
      retval = 0;
      break;
    }

cleanup:
    krb5_free_keyblock_contents(context, &encrypting_key);
    return retval;
}

static krb5_error_code
verify_sam_response(krb5_context context, krb5_db_entry *client,
                    krb5_data *req_pkt,
                    krb5_kdc_req *request, krb5_enc_tkt_part *enc_tkt_reply,
                    krb5_pa_data *pa,
                    preauth_get_entry_data_proc sam_get_entry_data,
                    void *pa_system_context,
                    void **pa_request_context,
                    krb5_data **e_data,
                    krb5_authdata ***authz_data)
{
    krb5_error_code             retval;
    krb5_data                   scratch;
    krb5_sam_response           *sr = 0;
    krb5_predicted_sam_response *psr = 0;
    krb5_enc_sam_response_enc   *esre = 0;
    krb5_timestamp              timenow;
    char                        *princ_req = 0, *princ_psr = 0;

    scratch.data = (char *) pa->contents;
    scratch.length = pa->length;
    
    if ((retval = decode_krb5_sam_response(&scratch, &sr))) {
        scratch.data = 0;
        com_err("krb5kdc", retval, gettext("decode_krb5_sam_response failed"));
        goto cleanup;
    }

    /* XXX We can only handle the challenge/response model of SAM.
           See passwords-04, par 4.1, 4.2 */
    {
      krb5_enc_data tmpdata;

      tmpdata.enctype = ENCTYPE_UNKNOWN;
      tmpdata.ciphertext = sr->sam_track_id;

      scratch.length = tmpdata.ciphertext.length;
      if ((scratch.data = (char *) malloc(scratch.length)) == NULL) {
          retval = ENOMEM;
          goto cleanup;
      }

      if ((retval = krb5_c_decrypt(context, &psr_key, /* XXX */ 0, 0,
                                   &tmpdata, &scratch))) {
          com_err(gettext("krb5kdc"),
                retval,
                gettext("decrypt track_id failed"));
          goto cleanup;
      }
    }

    if ((retval = decode_krb5_predicted_sam_response(&scratch, &psr))) {
        com_err(gettext("krb5kdc"), retval,
                gettext("decode_krb5_predicted_sam_response failed -- replay attack?"));
        goto cleanup;
    }

    /* Replay detection */
    if ((retval = krb5_unparse_name(context, request->client, &princ_req)))
        goto cleanup;
    if ((retval = krb5_unparse_name(context, psr->client, &princ_psr)))
        goto cleanup;
    if (strcmp(princ_req, princ_psr) != 0) {
        com_err("krb5kdc", retval = KRB5KDC_ERR_PREAUTH_FAILED,
                gettext("Principal mismatch in SAM psr! -- replay attack?"));
        goto cleanup;
    }

    if ((retval = krb5_timeofday(context, &timenow)))
        goto cleanup;

#ifdef USE_RCACHE
    {
        krb5_donot_replay rep;
        extern krb5_deltat rc_lifetime;
        /*
         * Verify this response came back in a timely manner.
         * We do this b/c otherwise very old (expunged from the rcache)
         * psr's would be able to be replayed.
         */
        if (timenow - psr->stime > rc_lifetime) {
            com_err("krb5kdc", retval = KRB5KDC_ERR_PREAUTH_FAILED,
            gettext("SAM psr came back too late! -- replay attack?"));
            goto cleanup;
        }

        /* Now check the replay cache. */
        rep.client = princ_psr;
        rep.server = "SAM/rc";  /* Should not match any principal name. */
        rep.ctime = psr->stime;
        rep.cusec = psr->susec;
        retval = krb5_rc_store(kdc_context, kdc_rcache, &rep);
        if (retval) {
            com_err("krb5kdc", retval, gettext("SAM psr replay attack!"));
            goto cleanup;
        }
    }
#endif /* USE_RCACHE */


    {
        free(scratch.data);
        scratch.length = sr->sam_enc_nonce_or_ts.ciphertext.length;
        if ((scratch.data = (char *) malloc(scratch.length)) == NULL) {
            retval = ENOMEM;
            goto cleanup;
        }

        if ((retval = krb5_c_decrypt(context, &psr->sam_key, /* XXX */ 0,
                                     0, &sr->sam_enc_nonce_or_ts, &scratch))) {
            com_err("krb5kdc", retval, gettext("decrypt nonce_or_ts failed"));
            goto cleanup;
        }
    }

    if ((retval = decode_krb5_enc_sam_response_enc(&scratch, &esre))) {
        com_err("krb5kdc", retval, gettext("decode_krb5_enc_sam_response_enc failed"));
        goto cleanup;
    }

    if (esre->sam_timestamp != sr->sam_patimestamp) {
      retval = KRB5KDC_ERR_PREAUTH_FAILED;
      goto cleanup;
    }
    
    if (labs(timenow - sr->sam_patimestamp) > context->clockskew) {
        retval = KRB5KRB_AP_ERR_SKEW;
        goto cleanup;
    }

    setflag(enc_tkt_reply->flags, TKT_FLG_HW_AUTH);

  cleanup:
    if (retval) com_err(gettext("krb5kdc"), 
                        retval,
                        gettext("sam verify failure"));
    free(scratch.data);
    free(sr);
    free(psr);
    free(esre);
    free(princ_psr);
    free(princ_req);

    return retval;
}