예제 #1
0
krb5_error_code
verify_securid_data_2(krb5_context context, krb5_db_entry *client,
                      krb5_sam_response_2 *sr2,
                      krb5_enc_tkt_part *enc_tkt_reply, krb5_pa_data *pa,
                      krb5_sam_challenge_2 **sc2_out)
{
    krb5_error_code retval;
    int new_pin = 0;
    krb5_key_data *client_key_data = NULL;
    krb5_keyblock client_key;
    krb5_data scratch;
    krb5_enc_sam_response_enc_2 *esre2 = NULL;
    struct securid_track_data sid_track_data, *trackp = NULL;
    krb5_data tmp_data;
    SDI_HANDLE sd_handle = SDI_HANDLE_NONE;
    krb5_sam_challenge_2 *sc2p = NULL;
    char *cp, *user = NULL;
    char *securid_user = NULL;
    char passcode[LENPRNST+1];
    char max_pin_len, min_pin_len, alpha_pin;

    memset(&client_key, 0, sizeof(client_key));
    memset(&scratch, 0, sizeof(scratch));
    *sc2_out = NULL;

    retval = krb5_unparse_name(context, client->princ, &user);
    if (retval != 0) {
        com_err("krb5kdc", retval,
                "while unparsing client name in verify_securid_data_2");
        return retval;
    }

    if ((sr2->sam_enc_nonce_or_sad.ciphertext.data == NULL) ||
        (sr2->sam_enc_nonce_or_sad.ciphertext.length <= 0)) {
          retval = KRB5KDC_ERR_PREAUTH_FAILED;
          krb5_set_error_message(context, retval,
                                 "No preauth data supplied in "
                                 "verify_securid_data_2 (%s)", user);
          goto cleanup;
    }

    retval = krb5_dbe_find_enctype(context, client,
                                   sr2->sam_enc_nonce_or_sad.enctype,
                                   KRB5_KDB_SALTTYPE_NORMAL,
                                   sr2->sam_enc_nonce_or_sad.kvno,
                                   &client_key_data);
    if (retval) {
        com_err("krb5kdc", retval,
                "while getting client key in verify_securid_data_2 (%s)",
                user);
        goto cleanup;
    }

    retval = krb5_dbe_decrypt_key_data(context, NULL, client_key_data,
                                       &client_key, NULL);
    if (retval != 0) {
        com_err("krb5kdc", retval,
                "while decrypting client key in verify_securid_data_2 (%s)",
                user);
        goto cleanup;
    }

    scratch.length = sr2->sam_enc_nonce_or_sad.ciphertext.length;
    scratch.data = k5alloc(scratch.length, &retval);
    if (retval)
        goto cleanup;
    retval = krb5_c_decrypt(context, &client_key,
                            KRB5_KEYUSAGE_PA_SAM_RESPONSE, 0,
                            &sr2->sam_enc_nonce_or_sad, &scratch);
    if (retval) {
        com_err("krb5kdc", retval,
                "while decrypting SAD in verify_securid_data_2 (%s)", user);
        goto cleanup;
    }

    retval = decode_krb5_enc_sam_response_enc_2(&scratch, &esre2);
    if (retval) {
        com_err("krb5kdc", retval,
                "while decoding SAD in verify_securid_data_2 (%s)", user);
        esre2 = NULL;
        goto cleanup;
    }

    if (sr2->sam_nonce != esre2->sam_nonce) {
        com_err("krb5kdc", KRB5KDC_ERR_PREAUTH_FAILED,
                "while checking nonce in verify_securid_data_2 (%s)", user);
        retval = KRB5KDC_ERR_PREAUTH_FAILED;
        goto cleanup;
    }

    if (esre2->sam_sad.length == 0 || esre2->sam_sad.data == NULL) {
        com_err("krb5kdc", KRB5KDC_ERR_PREAUTH_FAILED,
                "No SecurID passcode in verify_securid_data_2 (%s)", user);
        retval = KRB5KDC_ERR_PREAUTH_FAILED;
        goto cleanup;
    }

    /* Copy out SAD to null-terminated buffer */
    memset(passcode, 0, sizeof(passcode));
    if (esre2->sam_sad.length > (sizeof(passcode) - 1)) {
        retval = KRB5KDC_ERR_PREAUTH_FAILED;
        com_err("krb5kdc", retval,
                "SecurID passcode/PIN too long (%d bytes) in "
                "verify_securid_data_2 (%s)",
                esre2->sam_sad.length, user);
        goto cleanup;
    }
    memcpy(passcode, esre2->sam_sad.data, esre2->sam_sad.length);

    securid_user = strdup(user);
    if (!securid_user) {
        retval = ENOMEM;
        com_err("krb5kdc", ENOMEM,
                "while copying user name in verify_securid_data_2 (%s)", user);
        goto cleanup;
    }
    cp = strchr(securid_user, '@');
    if (cp != NULL)
        *cp = '\0';

    /* Check for any track_id data that may have state from a previous attempt
     * at SecurID authentication. */

    if (sr2->sam_track_id.data && (sr2->sam_track_id.length > 0)) {
        krb5_data track_id_data;

        memset(&track_id_data, 0, sizeof(track_id_data));
        retval = securid_decrypt_track_data_2(context, client,
                                              &sr2->sam_track_id,
                                              &track_id_data);
        if (retval) {
            com_err("krb5kdc", retval,
                    "while decrypting SecurID trackID in "
                    "verify_securid_data_2 (%s)", user);
           goto cleanup;
        }
        if (track_id_data.length < sizeof (struct securid_track_data)) {
            retval = KRB5KDC_ERR_PREAUTH_FAILED;
            com_err("krb5kdc", retval, "Length of track data incorrect");
            goto cleanup;
        }
        trackp = (struct securid_track_data *)track_id_data.data;

        if(trackp->hostid != gethostid()) {
            krb5_klog_syslog(LOG_INFO, "Unexpected challenge response");
            retval = KRB5KDC_ERR_DISCARD;
            goto cleanup;
        }

        switch(trackp->state) {
        case SECURID_STATE_INITIAL:
            goto initial;
            break;
        case SECURID_STATE_NEW_PIN_AGAIN:
        {
            int pin1_len, pin2_len;

            trackp->handle = ntohl(trackp->handle);
            pin2_len = strlen(passcode);
            pin1_len = strlen(trackp->passcode);

            if ((pin1_len != pin2_len) ||
                (memcmp(passcode, trackp->passcode, pin1_len) != 0)) {
                retval = KRB5KDC_ERR_PREAUTH_FAILED;
                krb5_klog_syslog(LOG_INFO, "New SecurID PIN Failed for user "
                                 "%s: PIN mis-match", user);
                break;
            }
            retval = SD_Pin(trackp->handle, passcode);
            SD_Close(trackp->handle);
            if (retval == ACM_NEW_PIN_ACCEPTED) {
                enc_tkt_reply->flags|=  TKT_FLG_HW_AUTH;
                enc_tkt_reply->flags|=  TKT_FLG_PRE_AUTH;
                krb5_klog_syslog(LOG_INFO, "SecurID PIN Accepted for %s in "
                                 "verify_securid_data_2",
                                 securid_user);
                retval = 0;
            } else {
                retval = KRB5KDC_ERR_PREAUTH_FAILED;
                krb5_klog_syslog(LOG_INFO,
                                 "SecurID PIN Failed for user %s (AceServer "
                                 "returns %d) in verify_securid_data_2",
                                 user, retval);
            }
            break;
        }
        case SECURID_STATE_NEW_PIN: {
            krb5_sam_challenge_2_body sc2b;
            sc2p = k5alloc(sizeof *sc2p, &retval);
            if (retval)
                goto cleanup;
            memset(sc2p, 0, sizeof(*sc2p));
            memset(&sc2b, 0, sizeof(sc2b));
            sc2b.sam_type = PA_SAM_TYPE_SECURID;
            sc2b.sam_response_prompt.data = NEW_PIN_AGAIN_message;
            sc2b.sam_response_prompt.length =
                strlen(sc2b.sam_response_prompt.data);
            sc2b.sam_flags = KRB5_SAM_SEND_ENCRYPTED_SAD;
            sc2b.sam_etype = client_key.enctype;

            tmp_data.data = (char *)&sc2b.sam_nonce;
            tmp_data.length = sizeof(sc2b.sam_nonce);
            if ((retval = krb5_c_random_make_octets(context, &tmp_data))) {
                com_err("krb5kdc", retval,
                        "while making nonce for SecurID new "
                        "PIN2 SAM_CHALLENGE_2 (%s)", user);
                goto cleanup;
            }
            sid_track_data.state = SECURID_STATE_NEW_PIN_AGAIN;
            sid_track_data.handle = trackp->handle;
            sid_track_data.hostid = gethostid();
            /* Should we complain if sizes don't work ??  */
            memcpy(sid_track_data.passcode, passcode,
                   sizeof(sid_track_data.passcode));
            tmp_data.data = (char *)&sid_track_data;
            tmp_data.length = sizeof(sid_track_data);
            if ((retval = securid_encrypt_track_data_2(context, client,
                                                       &tmp_data,
                                                       &sc2b.sam_track_id))) {
                com_err("krb5kdc", retval,
                        "while encrypting NEW PIN2 SecurID "
                        "track data for SAM_CHALLENGE_2 (%s)",
                        securid_user);
                goto cleanup;
            }
            retval = securid_make_sam_challenge_2_and_cksum(context, sc2p,
                                                            &sc2b,
                                                            &client_key);
            if (retval) {
                com_err("krb5kdc", retval,
                        "while making cksum for "
                        "SAM_CHALLENGE_2 (new PIN2) (%s)", securid_user);
                goto cleanup;
            }
            krb5_klog_syslog(LOG_INFO,
                             "Requesting verification of new PIN for user %s",
                             securid_user);
            *sc2_out = sc2p;
            sc2p = NULL;
            /*sc2_out may be set even on error path*/
            retval = KRB5KDC_ERR_PREAUTH_REQUIRED;
            goto cleanup;
        }
        case SECURID_STATE_NEXT_CODE:
            trackp->handle = ntohl(trackp->handle);
            retval = SD_Next(trackp->handle, passcode);
            SD_Close(trackp->handle);
            if (retval == ACM_OK) {
                enc_tkt_reply->flags |=  TKT_FLG_HW_AUTH | TKT_FLG_PRE_AUTH;

                krb5_klog_syslog(LOG_INFO, "Next SecurID Code Accepted for "
                                 "user %s", securid_user);
                retval = 0;
            } else {
                krb5_klog_syslog(LOG_INFO, "Next SecurID Code Failed for user "
                                 "%s (AceServer returns %d) in "
                                 "verify_securid_data_2", user, retval);
                retval = KRB5KDC_ERR_PREAUTH_FAILED;
            }
            break;
        }
    } else {            /* No track data, this is first of N attempts */
    initial:
        retval = SD_Init(&sd_handle);
        if (retval) {
            com_err("krb5kdc", KRB5KDC_ERR_PREAUTH_FAILED,
                    "SD_Init() returns error %d in verify_securid_data_2 (%s)",
                    retval, securid_user);
            retval = KRB5KDC_ERR_PREAUTH_FAILED;
            goto cleanup;
        }

        retval = SD_Lock(sd_handle, securid_user);
        if (retval != ACM_OK) {
            SD_Close(sd_handle);
            retval = KRB5KDC_ERR_PREAUTH_FAILED;
            krb5_klog_syslog(LOG_INFO,
                             "SD_Lock() failed (AceServer returns %d) for %s",
                             retval, securid_user);
            goto cleanup;
        }

        retval = SD_Check(sd_handle, passcode, securid_user);
        switch (retval) {
        case ACM_OK:
            SD_Close(sd_handle);
            enc_tkt_reply->flags|=  TKT_FLG_HW_AUTH;
            enc_tkt_reply->flags|=  TKT_FLG_PRE_AUTH;
            krb5_klog_syslog(LOG_INFO, "SecurID passcode accepted for user %s",
                             user);
            retval = 0;
            break;
        case ACM_ACCESS_DENIED:
            SD_Close(sd_handle);
            retval = KRB5KDC_ERR_PREAUTH_FAILED;
            krb5_klog_syslog(LOG_INFO, "AceServer returns Access Denied for "
                             "user %s (SAM2)", user);
            goto cleanup;
        case ACM_NEW_PIN_REQUIRED:
            new_pin = 1;
            /*fall through*/
        case ACM_NEXT_CODE_REQUIRED: {
            krb5_sam_challenge_2_body sc2b;
            sc2p = k5alloc(sizeof *sc2p, &retval);
            if (retval)
                goto cleanup;

            memset(sc2p, 0, sizeof(*sc2p));
            memset(&sc2b, 0, sizeof(sc2b));

            sc2b.sam_type = PA_SAM_TYPE_SECURID;
            sc2b.sam_response_prompt.data = NEXT_PASSCODE_message;
            sc2b.sam_response_prompt.length =
                strlen(sc2b.sam_response_prompt.data);
            sc2b.sam_flags = KRB5_SAM_SEND_ENCRYPTED_SAD;
            sc2b.sam_etype = client_key.enctype;
            if (new_pin) {
                if ((AceGetMaxPinLen(sd_handle, &max_pin_len) == ACE_SUCCESS)
                    && (AceGetMinPinLen(sd_handle,
                                        &min_pin_len) == ACE_SUCCESS)
                    && (AceGetAlphanumeric(sd_handle,
                                           &alpha_pin) == ACE_SUCCESS)) {
                    sprintf(PIN_message,
                            "New PIN must contain %d to %d %sdigits",
                            min_pin_len, max_pin_len,
                            (alpha_pin == 0) ? "" : "alphanumeric ");
                    sc2b.sam_challenge_label.data = PIN_message;
                    sc2b.sam_challenge_label.length =
                        strlen(sc2b.sam_challenge_label.data);
                } else {
                    sc2b.sam_challenge_label.length = 0;
                }
            }

            tmp_data.data = (char *)&sc2b.sam_nonce;
            tmp_data.length = sizeof(sc2b.sam_nonce);
            if ((retval = krb5_c_random_make_octets(context, &tmp_data))) {
                com_err("krb5kdc", retval,
                        "while making nonce for SecurID SAM_CHALLENGE_2 (%s)",
                        user);
                goto cleanup;
            }
            if (new_pin)
                sid_track_data.state = SECURID_STATE_NEW_PIN;
            else
                sid_track_data.state = SECURID_STATE_NEXT_CODE;
            sid_track_data.handle = htonl(sd_handle);
            sid_track_data.hostid = gethostid();
            tmp_data.data = (char *)&sid_track_data;
            tmp_data.length = sizeof(sid_track_data);
            retval = securid_encrypt_track_data_2(context, client, &tmp_data,
                                                  &sc2b.sam_track_id);
            if (retval) {
                   com_err("krb5kdc", retval,
                           "while encrypting SecurID track "
                           "data for SAM_CHALLENGE_2 (%s)",
                           securid_user);
                   goto cleanup;
            }
            retval = securid_make_sam_challenge_2_and_cksum(context, sc2p,
                                                            &sc2b,
                                                            &client_key);
            if (retval) {
                com_err("krb5kdc", retval,
                        "while making cksum for SAM_CHALLENGE_2 (%s)",
                        securid_user);
            }
            if (new_pin)
                krb5_klog_syslog(LOG_INFO, "New SecurID PIN required for "
                                 "user %s", securid_user);
            else
                krb5_klog_syslog(LOG_INFO, "Next SecurID passcode required "
                                 "for user %s", securid_user);
            *sc2_out = sc2p;
            sc2p = NULL;
            retval = KRB5KDC_ERR_PREAUTH_REQUIRED;
            /*sc2_out is permitted as an output on error path*/
            goto cleanup;
        }
        default:
            com_err("krb5kdc", KRB5KDC_ERR_PREAUTH_FAILED,
                    "AceServer returns unknown error code %d "
                    "in verify_securid_data_2\n", retval);
            retval = KRB5KDC_ERR_PREAUTH_FAILED;
            goto cleanup;
        }
    }   /* no track_id data */

cleanup:
    krb5_free_keyblock_contents(context, &client_key);
    free(scratch.data);
    krb5_free_enc_sam_response_enc_2(context, esre2);
    free(user);
    free(securid_user);
    free(trackp);
    krb5_free_sam_challenge_2(context, sc2p);
    return retval;
}
예제 #2
0
static void
kdc_verify_preauth(krb5_context context, krb5_data *req_pkt,
                   krb5_kdc_req *request, krb5_enc_tkt_part *enc_tkt_reply,
                   krb5_pa_data *pa_data, krb5_kdcpreauth_callbacks cb,
                   krb5_kdcpreauth_rock rock, krb5_kdcpreauth_moddata moddata,
                   krb5_kdcpreauth_verify_respond_fn respond, void *arg)
{
    krb5_error_code retval, saved_retval = 0;
    krb5_sam_response_2 *sr2 = NULL;
    krb5_data scratch, *scratch2, *e_data = NULL;
    char *client_name = NULL;
    krb5_sam_challenge_2 *out_sc2 = NULL;
    krb5_db_entry *client = cb->client_entry(context, rock);

    scratch.data = (char *) pa_data->contents;
    scratch.length = pa_data->length;

    retval = krb5_unparse_name(context, client->princ, &client_name);
    if (retval)
        goto cleanup;

    retval = decode_krb5_sam_response_2(&scratch, &sr2);
    if (retval) {
        com_err("krb5kdc",  retval,
                "while decoding SAM_RESPONSE_2 in verify_sam_response_2");
        sr2 = NULL;
        goto cleanup;
    }

    switch (sr2->sam_type) {
#ifdef ARL_SECURID_PREAUTH
    case PA_SAM_TYPE_SECURID:
        retval = verify_securid_data_2(context, client, sr2, enc_tkt_reply,
                                       pa_data, &out_sc2);
        if (retval)
            goto cleanup;
        break;
#endif  /* ARL_SECURID_PREAUTH */
#ifdef GRAIL_PREAUTH
    case PA_SAM_TYPE_GRAIL:
        retval = verify_grail_data(context, client, sr2, enc_tkt_reply,
                                   pa_data, &out_sc2);
        if (retval)
            goto cleanup;
        break;
#endif /* GRAIL_PREAUTH */
    default:
        retval = KRB5_PREAUTH_BAD_TYPE;
        com_err("krb5kdc", retval, "while verifying SAM 2 data");
        break;
    }

    /*
     * It is up to the method-specific verify routine to set the
     * ticket flags to indicate TKT_FLG_HW_AUTH and/or
     * TKT_FLG_PRE_AUTH.  Some methods may require more than one round
     * of dialog with the client and must return successfully from
     * their verify routine.  If does not set the TGT flags, the
     * required_preauth conditions will not be met and it will try
     * again to get enough preauth data from the client.  Do not set
     * TGT flags here.
     */
cleanup:
    /*
     * Note that e_data is an output even in error conditions.  If we
     * successfully encode the output e_data, we return whatever error is
     * received above.  Otherwise we return the encoding error.
     */
    saved_retval = retval;
    if (out_sc2) {
        krb5_pa_data pa_out;
        krb5_pa_data *pa_array[2];
        pa_array[0] = &pa_out;
        pa_array[1] = NULL;
        pa_out.pa_type = KRB5_PADATA_SAM_CHALLENGE_2;
        retval = encode_krb5_sam_challenge_2(out_sc2, &scratch2);
        krb5_free_sam_challenge_2(context, out_sc2);
        if (retval)
            goto encode_error;
        pa_out.contents = (krb5_octet *) scratch2->data;
        pa_out.length = scratch2->length;
        retval = encode_krb5_padata_sequence(pa_array, &e_data);
        krb5_free_data(context, scratch2);
    }
encode_error:
    krb5_free_sam_response_2(context, sr2);
    free(client_name);
    if (retval == 0)
        retval = saved_retval;

    (*respond)(arg, retval, NULL, NULL, NULL);
}
예제 #3
0
static krb5_error_code
sam2_process(krb5_context context, krb5_clpreauth_moddata moddata,
	     krb5_clpreauth_modreq modreq, krb5_get_init_creds_opt *opt,
	     krb5_clpreauth_callbacks cb, krb5_clpreauth_rock rock,
	     krb5_kdc_req *request, krb5_data *encoded_request_body,
	     krb5_data *encoded_previous_request, krb5_pa_data *padata,
	     krb5_prompter_fct prompter, void *prompter_data,
	     krb5_pa_data ***out_padata)
{
    krb5_error_code retval;
    krb5_sam_challenge_2 *sc2 = NULL;
    krb5_sam_challenge_2_body *sc2b = NULL;
    krb5_data tmp_data;
    krb5_data response_data;
    char name[100], banner[100], prompt[100], response[100];
    krb5_prompt kprompt;
    krb5_prompt_type prompt_type;
    krb5_data defsalt, *salt;
    krb5_checksum **cksum;
    krb5_data *scratch = NULL;
    krb5_boolean valid_cksum = 0;
    krb5_enc_sam_response_enc_2 enc_sam_response_enc_2;
    krb5_sam_response_2 sr2;
    size_t ciph_len;
    krb5_pa_data **sam_padata;

    if (prompter == NULL)
        return KRB5_LIBOS_CANTREADPWD;

    tmp_data.length = padata->length;
    tmp_data.data = (char *)padata->contents;

    if ((retval = decode_krb5_sam_challenge_2(&tmp_data, &sc2)))
        return(retval);

    retval = decode_krb5_sam_challenge_2_body(&sc2->sam_challenge_2_body, &sc2b);

    if (retval) {
        krb5_free_sam_challenge_2(context, sc2);
        return(retval);
    }

    if (!sc2->sam_cksum || ! *sc2->sam_cksum) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        return(KRB5_SAM_NO_CHECKSUM);
    }

    if (sc2b->sam_flags & KRB5_SAM_MUST_PK_ENCRYPT_SAD) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        return(KRB5_SAM_UNSUPPORTED);
    }

    if (!krb5_c_valid_enctype(sc2b->sam_etype)) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        return(KRB5_SAM_INVALID_ETYPE);
    }

    /* All of the above error checks are KDC-specific, that is, they     */
    /* assume a failure in the KDC reply.  By returning anything other   */
    /* than KRB5_KDC_UNREACH, KRB5_PREAUTH_FAILED,               */
    /* KRB5_LIBOS_PWDINTR, or KRB5_REALM_CANT_RESOLVE, the client will   */
    /* most likely go on to try the AS_REQ against master KDC            */

    if (!(sc2b->sam_flags & KRB5_SAM_USE_SAD_AS_KEY)) {
        /* We will need the password to obtain the key used for */
        /* the checksum, and encryption of the sam_response.    */
        /* Go ahead and get it now, preserving the ordering of  */
        /* prompts for the user.                                */

        retval = (*rock->gak_fct)(context, request->client, sc2b->sam_etype,
				  prompter, prompter_data, rock->salt,
				  rock->s2kparams, rock->as_key,
				  *rock->gak_data);
        if (retval) {
            krb5_free_sam_challenge_2(context, sc2);
            krb5_free_sam_challenge_2_body(context, sc2b);
            return(retval);
        }
    }

    snprintf(name, sizeof(name), "%.*s",
             SAMDATA(sc2b->sam_type_name, _("SAM Authentication"),
                     sizeof(name) - 1));

    snprintf(banner, sizeof(banner), "%.*s",
             SAMDATA(sc2b->sam_challenge_label,
                     sam_challenge_banner(sc2b->sam_type),
                     sizeof(banner)-1));

    snprintf(prompt, sizeof(prompt), "%s%.*s%s%.*s",
             sc2b->sam_challenge.length?"Challenge is [":"",
             SAMDATA(sc2b->sam_challenge, "", 20),
             sc2b->sam_challenge.length?"], ":"",
             SAMDATA(sc2b->sam_response_prompt, "passcode", 55));

    response_data.data = response;
    response_data.length = sizeof(response);
    kprompt.prompt = prompt;
    kprompt.hidden = 1;
    kprompt.reply = &response_data;

    prompt_type = KRB5_PROMPT_TYPE_PREAUTH;
    krb5int_set_prompt_types(context, &prompt_type);

    if ((retval = ((*prompter)(context, prompter_data, name,
                               banner, 1, &kprompt)))) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        krb5int_set_prompt_types(context, 0);
        return(retval);
    }

    krb5int_set_prompt_types(context, (krb5_prompt_type *)NULL);

    /* Generate salt used by string_to_key() */
    salt = rock->salt;
    if (((int) salt->length == -1) && (salt->data == NULL)) {
        if ((retval =
             krb5_principal2salt(context, request->client, &defsalt))) {
            krb5_free_sam_challenge_2(context, sc2);
            krb5_free_sam_challenge_2_body(context, sc2b);
            return(retval);
        }
        salt = &defsalt;
    } else {
        defsalt.length = 0;
    }

    /* Get encryption key to be used for checksum and sam_response */
    if (!(sc2b->sam_flags & KRB5_SAM_USE_SAD_AS_KEY)) {
        /* as_key = string_to_key(password) */

        if (rock->as_key->length) {
            krb5_free_keyblock_contents(context, rock->as_key);
            rock->as_key->length = 0;
        }

        /* generate a key using the supplied password */
        retval = krb5_c_string_to_key(context, sc2b->sam_etype,
				      (krb5_data *)*rock->gak_data, salt,
				      rock->as_key);

        if (retval) {
            krb5_free_sam_challenge_2(context, sc2);
            krb5_free_sam_challenge_2_body(context, sc2b);
            if (defsalt.length) free(defsalt.data);
            return(retval);
        }

        if (!(sc2b->sam_flags & KRB5_SAM_SEND_ENCRYPTED_SAD)) {
            /* as_key = combine_key (as_key, string_to_key(SAD)) */
            krb5_keyblock tmp_kb;

            retval = krb5_c_string_to_key(context, sc2b->sam_etype,
                                          &response_data, salt, &tmp_kb);

            if (retval) {
                krb5_free_sam_challenge_2(context, sc2);
                krb5_free_sam_challenge_2_body(context, sc2b);
                if (defsalt.length) free(defsalt.data);
                return(retval);
            }

            /* This should be a call to the crypto library some day */
            /* key types should already match the sam_etype */
            retval = krb5int_c_combine_keys(context, rock->as_key, &tmp_kb,
					    rock->as_key);

            if (retval) {
                krb5_free_sam_challenge_2(context, sc2);
                krb5_free_sam_challenge_2_body(context, sc2b);
                if (defsalt.length) free(defsalt.data);
                return(retval);
            }
            krb5_free_keyblock_contents(context, &tmp_kb);
        }

        if (defsalt.length)
            free(defsalt.data);

    } else {
        /* as_key = string_to_key(SAD) */

        if (rock->as_key->length) {
            krb5_free_keyblock_contents(context, rock->as_key);
            rock->as_key->length = 0;
        }

        /* generate a key using the supplied password */
        retval = krb5_c_string_to_key(context, sc2b->sam_etype,
                                      &response_data, salt, rock->as_key);

        if (defsalt.length)
            free(defsalt.data);

        if (retval) {
            krb5_free_sam_challenge_2(context, sc2);
            krb5_free_sam_challenge_2_body(context, sc2b);
            return(retval);
        }
    }

    /* Now we have a key, verify the checksum on the sam_challenge */

    cksum = sc2->sam_cksum;

    for (; *cksum; cksum++) {
        if (!krb5_c_is_keyed_cksum((*cksum)->checksum_type))
            continue;
        /* Check this cksum */
        retval = krb5_c_verify_checksum(context, rock->as_key,
                                        KRB5_KEYUSAGE_PA_SAM_CHALLENGE_CKSUM,
                                        &sc2->sam_challenge_2_body,
                                        *cksum, &valid_cksum);
        if (retval) {
            krb5_free_data(context, scratch);
            krb5_free_sam_challenge_2(context, sc2);
            krb5_free_sam_challenge_2_body(context, sc2b);
            return(retval);
        }
        if (valid_cksum)
            break;
    }

    if (!valid_cksum) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        /*
         * Note: We return AP_ERR_BAD_INTEGRITY so upper-level applications
         * can interpret that as "password incorrect", which is probably
         * the best error we can return in this situation.
         */
        return(KRB5KRB_AP_ERR_BAD_INTEGRITY);
    }

    /* fill in enc_sam_response_enc_2 */
    enc_sam_response_enc_2.magic = KV5M_ENC_SAM_RESPONSE_ENC_2;
    enc_sam_response_enc_2.sam_nonce = sc2b->sam_nonce;
    if (sc2b->sam_flags & KRB5_SAM_SEND_ENCRYPTED_SAD) {
        enc_sam_response_enc_2.sam_sad = response_data;
    } else {
        enc_sam_response_enc_2.sam_sad.data = NULL;
        enc_sam_response_enc_2.sam_sad.length = 0;
    }

    /* encode and encrypt enc_sam_response_enc_2 with as_key */
    retval = encode_krb5_enc_sam_response_enc_2(&enc_sam_response_enc_2,
                                                &scratch);
    if (retval) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        return(retval);
    }

    /* Fill in sam_response_2 */
    memset(&sr2, 0, sizeof(sr2));
    sr2.sam_type = sc2b->sam_type;
    sr2.sam_flags = sc2b->sam_flags;
    sr2.sam_track_id = sc2b->sam_track_id;
    sr2.sam_nonce = sc2b->sam_nonce;

    /* Now take care of sr2.sam_enc_nonce_or_sad by encrypting encoded   */
    /* enc_sam_response_enc_2 from above */

    retval = krb5_c_encrypt_length(context, rock->as_key->enctype,
				   scratch->length, &ciph_len);
    if (retval) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        krb5_free_data(context, scratch);
        return(retval);
    }
    sr2.sam_enc_nonce_or_sad.ciphertext.length = ciph_len;

    sr2.sam_enc_nonce_or_sad.ciphertext.data =
        (char *)malloc(sr2.sam_enc_nonce_or_sad.ciphertext.length);

    if (!sr2.sam_enc_nonce_or_sad.ciphertext.data) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        krb5_free_data(context, scratch);
        return(ENOMEM);
    }

    retval = krb5_c_encrypt(context, rock->as_key,
			    KRB5_KEYUSAGE_PA_SAM_RESPONSE, NULL, scratch,
			    &sr2.sam_enc_nonce_or_sad);
    if (retval) {
        krb5_free_sam_challenge_2(context, sc2);
        krb5_free_sam_challenge_2_body(context, sc2b);
        krb5_free_data(context, scratch);
        krb5_free_data_contents(context, &sr2.sam_enc_nonce_or_sad.ciphertext);
        return(retval);
    }
    krb5_free_data(context, scratch);
    scratch = NULL;

    /* Encode the sam_response_2 */
    retval = encode_krb5_sam_response_2(&sr2, &scratch);
    krb5_free_sam_challenge_2(context, sc2);
    krb5_free_sam_challenge_2_body(context, sc2b);
    krb5_free_data_contents(context, &sr2.sam_enc_nonce_or_sad.ciphertext);

    if (retval) {
        return (retval);
    }

    /* Almost there, just need to make padata !  */
    sam_padata = malloc(2 * sizeof(*sam_padata));
    if (sam_padata == NULL) {
        krb5_free_data(context, scratch);
        return(ENOMEM);
    }
    sam_padata[0] = malloc(sizeof(krb5_pa_data));
    if (sam_padata[0] == NULL) {
        krb5_free_data(context, scratch);
	free(sam_padata);
        return(ENOMEM);
    }

    sam_padata[0]->magic = KV5M_PA_DATA;
    sam_padata[0]->pa_type = KRB5_PADATA_SAM_RESPONSE_2;
    sam_padata[0]->length = scratch->length;
    sam_padata[0]->contents = (krb5_octet *) scratch->data;
    free(scratch);
    sam_padata[1] = NULL;

    *out_padata = sam_padata;

    return(0);
}