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/** BEGIN COPYRIGHT BLOCK
* This Program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation; version 3 of the License.
*
* This Program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with
* this Program; if not, write to the Free Software Foundation, Inc., 59 Temple
* Place, Suite 330, Boston, MA 02111-1307 USA.
*
* In addition, as a special exception, Red Hat, Inc. gives You the additional
* right to link the code of this Program with code not covered under the GNU
* General Public License ("Non-GPL Code") and to distribute linked combinations
* including the two, subject to the limitations in this paragraph. Non-GPL Code
* permitted under this exception must only link to the code of this Program
* through those well defined interfaces identified in the file named EXCEPTION
* found in the source code files (the "Approved Interfaces"). The files of
* Non-GPL Code may instantiate templates or use macros or inline functions from
* the Approved Interfaces without causing the resulting work to be covered by
* the GNU General Public License. Only Red Hat, Inc. may make changes or
* additions to the list of Approved Interfaces. You must obey the GNU General
* Public License in all respects for all of the Program code and other code used
* in conjunction with the Program except the Non-GPL Code covered by this
* exception. If you modify this file, you may extend this exception to your
* version of the file, but you are not obligated to do so. If you do not wish to
* provide this exception without modification, you must delete this exception
* statement from your version and license this file solely under the GPL without
* exception.
*
*
* Copyright (C) 2013 Red Hat, Inc.
* All rights reserved.
* END COPYRIGHT BLOCK **/
/*
* This file contains an implementation of HOTP (RFC 4226) and TOTP (RFC 6238).
* For details of how these algorithms work, please see the relevant RFCs.
*/
#include <stdbool.h>
#include <time.h>
#include <nss.h>
#include <pk11pub.h>
#include <hasht.h>
#include <prnetdb.h>
struct digest_buffer {
uint8_t buf[SHA512_LENGTH];
unsigned int len;
};
static const struct {
const char *algo;
CK_MECHANISM_TYPE mech;
} algo2mech[] = {
{ "sha1", CKM_SHA_1_HMAC },
{ "sha256", CKM_SHA256_HMAC },
{ "sha384", CKM_SHA384_HMAC },
{ "sha512", CKM_SHA512_HMAC },
{ }
};
/*
* This code is mostly cargo-cult taken from here:
* http://www.mozilla.org/projects/security/pki/nss/tech-notes/tn5.html
*
* It should implement HMAC with the given mechanism (SHA: 1, 256, 384, 512).
*/
static bool hmac(SECItem *key, CK_MECHANISM_TYPE mech, const SECItem *in,
struct digest_buffer *out)
{
SECItem param = { siBuffer, NULL, 0 };
PK11SlotInfo *slot = NULL;
PK11SymKey *symkey = NULL;
PK11Context *ctx = NULL;
bool ret = false;
SECStatus s;
slot = PK11_GetBestSlot(mech, NULL);
if (slot == NULL) {
slot = PK11_GetInternalKeySlot();
if (slot == NULL) {
goto done;
}
}
symkey = PK11_ImportSymKey(slot, mech, PK11_OriginUnwrap,
CKA_SIGN, key, NULL);
if (symkey == NULL)
goto done;
ctx = PK11_CreateContextBySymKey(mech, CKA_SIGN, symkey, ¶m);
if (ctx == NULL)
goto done;
s = PK11_DigestBegin(ctx);
if (s != SECSuccess)
goto done;
s = PK11_DigestOp(ctx, in->data, in->len);
if (s != SECSuccess)
goto done;
s = PK11_DigestFinal(ctx, out->buf, &out->len, sizeof(out->buf));
if (s != SECSuccess)
goto done;
ret = true;
done:
if (ctx != NULL)
PK11_DestroyContext(ctx, PR_TRUE);
if (symkey != NULL)
PK11_FreeSymKey(symkey);
if (slot != NULL)
PK11_FreeSlot(slot);
return ret;
}
/*
* An implementation of HOTP (RFC 4226).
*/
bool ipapwd_hotp(const uint8_t *key, size_t len, const char *algo, int digits,
uint64_t counter, uint32_t *out)
{
const SECItem cntr = { siBuffer, (uint8_t *) &counter, sizeof(counter) };
SECItem keyitm = { siBuffer, (uint8_t *) key, len };
CK_MECHANISM_TYPE mech = CKM_SHA_1_HMAC;
PRUint64 offset, binary, div;
struct digest_buffer digest;
int i;
/* Convert counter to network byte order. */
counter = PR_htonll(counter);
/* Find the mech. */
for (i = 0; algo2mech[i].algo; i++) {
if (strcasecmp(algo2mech[i].algo, algo) == 0) {
mech = algo2mech[i].mech;
break;
}
}
/* Create the digits divisor. */
for (div = 1; digits > 0; digits--) {
div *= 10;
}
/* Do the digest. */
if (!hmac(&keyitm, mech, &cntr, &digest)) {
return false;
}
/* Truncate. */
offset = digest.buf[digest.len - 1] & 0xf;
binary = (digest.buf[offset + 0] & 0x7f) << 0x18;
binary |= (digest.buf[offset + 1] & 0xff) << 0x10;
binary |= (digest.buf[offset + 2] & 0xff) << 0x08;
binary |= (digest.buf[offset + 3] & 0xff) << 0x00;
binary = binary % div;
*out = binary;
return true;
}
/*
* An implementation of TOTP (RFC 6238).
*/
bool ipapwd_totp(const uint8_t *key, size_t len, const char *algo, int digits,
time_t time, int offset, unsigned int step, uint32_t *out)
{
if (step == 0)
return false;
return ipapwd_hotp(key, len, algo, digits, (time - offset) / step, out);
}
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