/*
silcauth.c
Author: Pekka Riikonen <priikone@silcnet.org>
Copyright (C) 2001 - 2003 Pekka Riikonen
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 2 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.
*/
/* $Id: silcauth.c,v 1.28.2.4 2003/10/03 08:00:49 priikone Exp $ */
#include "silcincludes.h"
#include "silcauth.h"
/******************************************************************************
Authentication Payload
******************************************************************************/
/* Authentication Payload structure */
struct SilcAuthPayloadStruct {
SilcUInt16 len;
SilcUInt16 auth_method;
SilcUInt16 random_len;
unsigned char *random_data;
SilcUInt16 auth_len;
unsigned char *auth_data;
};
/* Parses and returns Authentication Payload */
SilcAuthPayload silc_auth_payload_parse(const unsigned char *data,
SilcUInt32 data_len)
{
SilcBufferStruct buffer;
SilcAuthPayload newp;
int ret;
SILC_LOG_DEBUG(("Parsing Authentication Payload"));
silc_buffer_set(&buffer, (unsigned char *)data, data_len);
newp = silc_calloc(1, sizeof(*newp));
if (!newp)
return NULL;
/* Parse the payload */
ret = silc_buffer_unformat(&buffer,
SILC_STR_UI_SHORT(&newp->len),
SILC_STR_UI_SHORT(&newp->auth_method),
SILC_STR_UI16_NSTRING_ALLOC(&newp->random_data,
&newp->random_len),
SILC_STR_UI16_NSTRING_ALLOC(&newp->auth_data,
&newp->auth_len),
SILC_STR_END);
if (ret == -1) {
silc_free(newp);
return NULL;
}
if (newp->len != buffer.len ||
newp->random_len + newp->auth_len > buffer.len - 8) {
silc_auth_payload_free(newp);
return NULL;
}
/* Authentication data must be provided */
if (newp->auth_len < 1) {
silc_auth_payload_free(newp);
return NULL;
}
/* If password authentication, random data must not be set */
if (newp->auth_method == SILC_AUTH_PASSWORD && newp->random_len) {
silc_auth_payload_free(newp);
return NULL;
}
/* If public key authentication, random data must be at least 128 bytes */
if (newp->auth_method == SILC_AUTH_PUBLIC_KEY && newp->random_len < 128) {
silc_auth_payload_free(newp);
return NULL;
}
return newp;
}
/* Encodes authentication payload into buffer and returns it */
SilcBuffer silc_auth_payload_encode(SilcAuthMethod method,
const unsigned char *random_data,
SilcUInt16 random_len,
const unsigned char *auth_data,
SilcUInt16 auth_len)
{
SilcBuffer buffer;
SilcUInt32 len;
unsigned char *autf8 = NULL;
SilcUInt32 autf8_len;
SILC_LOG_DEBUG(("Encoding Authentication Payload"));
/* Passphrase MUST be UTF-8 encoded, encode if it is not */
if (method == SILC_AUTH_PASSWORD && !silc_utf8_valid(auth_data, auth_len)) {
autf8_len = silc_utf8_encoded_len(auth_data, auth_len, 0);
if (!autf8_len)
return NULL;
autf8 = silc_calloc(autf8_len, sizeof(*autf8));
auth_len = silc_utf8_encode(auth_data, auth_len, 0, autf8, autf8_len);
auth_data = (const unsigned char *)autf8;
}
len = 2 + 2 + 2 + random_len + 2 + auth_len;
buffer = silc_buffer_alloc_size(len);
if (!buffer) {
silc_free(autf8);
return NULL;
}
silc_buffer_format(buffer,
SILC_STR_UI_SHORT(len),
SILC_STR_UI_SHORT(method),
SILC_STR_UI_SHORT(random_len),
SILC_STR_UI_XNSTRING(random_data, random_len),
SILC_STR_UI_SHORT(auth_len),
SILC_STR_UI_XNSTRING(auth_data, auth_len),
SILC_STR_END);
silc_free(autf8);
return buffer;
}
/* Frees authentication payload. */
void silc_auth_payload_free(SilcAuthPayload payload)
{
if (payload) {
if (payload->random_data) {
memset(payload->random_data, 0, payload->random_len);
silc_free(payload->random_data);
}
if (payload->auth_data) {
memset(payload->auth_data, 0, payload->auth_len);
silc_free(payload->auth_data);
}
silc_free(payload);
}
}
/* Get authentication method */
SilcAuthMethod silc_auth_get_method(SilcAuthPayload payload)
{
return payload->auth_method;
}
/* Get the public data from the auth payload. */
unsigned char *silc_auth_get_public_data(SilcAuthPayload payload,
SilcUInt32 *pubdata_len)
{
if (pubdata_len)
*pubdata_len = (SilcUInt32)payload->random_len;
return payload->random_data;
}
/* Get the authentication data. If this is passphrase it is UTF-8 encoded. */
unsigned char *silc_auth_get_data(SilcAuthPayload payload,
SilcUInt32 *auth_len)
{
if (auth_len)
*auth_len = (SilcUInt32)payload->auth_len;
return payload->auth_data;
}
/******************************************************************************
Authentication Routines
******************************************************************************/
/* Encodes the authentication data for hashing and signing as the protocol
dictates. */
static unsigned char *
silc_auth_public_key_encode_data(SilcPublicKey public_key,
const unsigned char *randomdata,
SilcUInt32 random_len, const void *id,
SilcIdType type, SilcUInt32 *ret_len)
{
SilcBuffer buf;
unsigned char *pk, *id_data, *ret;
SilcUInt32 pk_len, id_len;
pk = silc_pkcs_public_key_encode(public_key, &pk_len);
if (!pk)
return NULL;
id_data = silc_id_id2str(id, type);
if (!id_data) {
silc_free(pk);
return NULL;
}
id_len = silc_id_get_len(id, type);
buf = silc_buffer_alloc_size(random_len + id_len + pk_len);
if (!buf) {
silc_free(pk);
silc_free(id_data);
return NULL;
}
silc_buffer_format(buf,
SILC_STR_UI_XNSTRING(randomdata, random_len),
SILC_STR_UI_XNSTRING(id_data, id_len),
SILC_STR_UI_XNSTRING(pk, pk_len),
SILC_STR_END);
ret = silc_buffer_steal(buf, ret_len);
silc_buffer_free(buf);
silc_free(id_data);
silc_free(pk);
return ret;
}
/* Generates Authentication Payload with authentication data. This is used
to do public key based authentication. This generates the random data
and the actual authentication data. Returns NULL on error. */
SilcBuffer silc_auth_public_key_auth_generate(SilcPublicKey public_key,
SilcPrivateKey private_key,
SilcRng rng, SilcHash hash,
const void *id, SilcIdType type)
{
unsigned char *randomdata;
SilcBuffer buf;
/* Get 256 bytes of random data */
if (rng)
randomdata = silc_rng_get_rn_data(rng, 256);
else
randomdata = silc_rng_global_get_rn_data(256);
if (!randomdata)
return NULL;
buf = silc_auth_public_key_auth_generate_wpub(public_key, private_key,
randomdata, 256, hash,
id, type);
memset(randomdata, 0, 256);
silc_free(randomdata);
return buf;
}
/* Generates Authentication Payload with authentication data. This is used
to do public key based authentication. This generates the random data
and the actual authentication data. Returns NULL on error. */
SilcBuffer
silc_auth_public_key_auth_generate_wpub(SilcPublicKey public_key,
SilcPrivateKey private_key,
const unsigned char *pubdata,
SilcUInt32 pubdata_len,
SilcHash hash,
const void *id, SilcIdType type)
{
unsigned char auth_data[2048 + 1];
SilcUInt32 auth_len;
unsigned char *tmp;
SilcUInt32 tmp_len;
SilcBuffer buf;
SilcPKCS pkcs;
SILC_LOG_DEBUG(("Generating Authentication Payload with data"));
/* Encode the auth data */
tmp = silc_auth_public_key_encode_data(public_key, pubdata, pubdata_len, id,
type, &tmp_len);
if (!tmp)
return NULL;
/* Allocate PKCS object */
if (!silc_pkcs_alloc(private_key->name, &pkcs)) {
memset(tmp, 0, tmp_len);
silc_free(tmp);
return NULL;
}
silc_pkcs_public_key_set(pkcs, public_key);
silc_pkcs_private_key_set(pkcs, private_key);
/* Compute the hash and the signature. */
if (silc_pkcs_get_key_len(pkcs) / 8 > sizeof(auth_data) - 1 ||
!silc_pkcs_sign_with_hash(pkcs, hash, tmp, tmp_len, auth_data,
&auth_len)) {
memset(tmp, 0, tmp_len);
silc_free(tmp);
silc_pkcs_free(pkcs);
return NULL;
}
/* Encode Authentication Payload */
buf = silc_auth_payload_encode(SILC_AUTH_PUBLIC_KEY, pubdata, pubdata_len,
auth_data, auth_len);
memset(tmp, 0, tmp_len);
memset(auth_data, 0, sizeof(auth_data));
silc_free(tmp);
silc_pkcs_free(pkcs);
return buf;
}
/* Verifies the authentication data. Returns TRUE if authentication was
successful. */
bool silc_auth_public_key_auth_verify(SilcAuthPayload payload,
SilcPublicKey public_key, SilcHash hash,
const void *id, SilcIdType type)
{
unsigned char *tmp;
SilcUInt32 tmp_len;
SilcPKCS pkcs;
SILC_LOG_DEBUG(("Verifying authentication data"));
/* Encode auth data */
tmp = silc_auth_public_key_encode_data(public_key, payload->random_data,
payload->random_len,
id, type, &tmp_len);
if (!tmp) {
SILC_LOG_DEBUG(("Authentication failed"));
return FALSE;
}
/* Allocate PKCS object */
if (!silc_pkcs_alloc(public_key->name, &pkcs)) {
memset(tmp, 0, tmp_len);
silc_free(tmp);
return FALSE;
}
silc_pkcs_public_key_set(pkcs, public_key);
/* Verify the authentication data */
if (!silc_pkcs_verify_with_hash(pkcs, hash, payload->auth_data,
payload->auth_len, tmp, tmp_len)) {
memset(tmp, 0, tmp_len);
silc_free(tmp);
silc_pkcs_free(pkcs);
SILC_LOG_DEBUG(("Authentication failed"));
return FALSE;
}
memset(tmp, 0, tmp_len);
silc_free(tmp);
silc_pkcs_free(pkcs);
SILC_LOG_DEBUG(("Authentication successful"));
return TRUE;
}
/* Same as above but the payload is not parsed yet. This will parse it. */
bool silc_auth_public_key_auth_verify_data(const unsigned char *payload,
SilcUInt32 payload_len,
SilcPublicKey public_key,
SilcHash hash,
const void *id, SilcIdType type)
{
SilcAuthPayload auth_payload;
int ret;
auth_payload = silc_auth_payload_parse(payload, payload_len);
if (!auth_payload) {
SILC_LOG_DEBUG(("Authentication failed"));
return FALSE;
}
ret = silc_auth_public_key_auth_verify(auth_payload, public_key, hash,
id, type);
silc_auth_payload_free(auth_payload);
return ret;
}
/* Verifies the authentication data directly from the Authentication
Payload. Supports all authentication methods. If the authentication
method is passphrase based then the `auth_data' and `auth_data_len'
are the passphrase and its length. If the method is public key
authentication then the `auth_data' is the SilcPublicKey and the
`auth_data_len' is ignored. */
bool silc_auth_verify(SilcAuthPayload payload, SilcAuthMethod auth_method,
const void *auth_data, SilcUInt32 auth_data_len,
SilcHash hash, const void *id, SilcIdType type)
{
SILC_LOG_DEBUG(("Verifying authentication"));
if (!payload || auth_method != payload->auth_method)
return FALSE;
switch (payload->auth_method) {
case SILC_AUTH_NONE:
/* No authentication */
SILC_LOG_DEBUG(("No authentication required"));
return TRUE;
case SILC_AUTH_PASSWORD:
/* Passphrase based authentication. The `pkcs', `hash', `id' and `type'
arguments are not needed. */
/* Sanity checks */
if ((payload->auth_len == 0) || !auth_data ||
payload->auth_len != auth_data_len)
break;
if (!memcmp(payload->auth_data, auth_data, auth_data_len)) {
SILC_LOG_DEBUG(("Passphrase Authentication successful"));
return TRUE;
}
break;
case SILC_AUTH_PUBLIC_KEY:
/* Public key based authentication */
return silc_auth_public_key_auth_verify(payload, (SilcPublicKey)auth_data,
hash, id, type);
break;
default:
break;
}
SILC_LOG_DEBUG(("Authentication failed"));
return FALSE;
}
/* Same as above but parses the authentication payload before verify. */
bool silc_auth_verify_data(const unsigned char *payload,
SilcUInt32 payload_len,
SilcAuthMethod auth_method, const void *auth_data,
SilcUInt32 auth_data_len, SilcHash hash,
const void *id, SilcIdType type)
{
SilcAuthPayload auth_payload;
bool ret;
auth_payload = silc_auth_payload_parse(payload, payload_len);
if (!auth_payload || (auth_payload->auth_len == 0))
return FALSE;
ret = silc_auth_verify(auth_payload, auth_method, auth_data, auth_data_len,
hash, id, type);
silc_auth_payload_free(auth_payload);
return ret;
}
/******************************************************************************
Key Agreement Payload
******************************************************************************/
/* The Key Agreement protocol structure */
struct SilcKeyAgreementPayloadStruct {
SilcUInt16 hostname_len;
unsigned char *hostname;
SilcUInt32 port;
};
/* Parses and returns an allocated Key Agreement payload. */
SilcKeyAgreementPayload
silc_key_agreement_payload_parse(const unsigned char *payload,
SilcUInt32 payload_len)
{
SilcBufferStruct buffer;
SilcKeyAgreementPayload newp;
int ret;
SILC_LOG_DEBUG(("Parsing Key Agreement Payload"));
silc_buffer_set(&buffer, (unsigned char *)payload, payload_len);
newp = silc_calloc(1, sizeof(*newp));
if (!newp)
return NULL;
/* Parse the payload */
ret = silc_buffer_unformat(&buffer,
SILC_STR_UI16_NSTRING_ALLOC(&newp->hostname,
&newp->hostname_len),
SILC_STR_UI_INT(&newp->port),
SILC_STR_END);
if (ret == -1 || newp->hostname_len > buffer.len - 6) {
silc_free(newp);
return NULL;
}
return newp;
}
/* Encodes the Key Agreement protocol and returns the encoded buffer */
SilcBuffer silc_key_agreement_payload_encode(const char *hostname,
SilcUInt32 port)
{
SilcBuffer buffer;
SilcUInt32 len = hostname ? strlen(hostname) : 0;
SILC_LOG_DEBUG(("Encoding Key Agreement Payload"));
buffer = silc_buffer_alloc_size(2 + len + 4);
if (!buffer)
return NULL;
silc_buffer_format(buffer,
SILC_STR_UI_SHORT(len),
SILC_STR_UI_XNSTRING(hostname, len),
SILC_STR_UI_INT(port),
SILC_STR_END);
return buffer;
}
/* Frees the Key Agreement protocol */
void silc_key_agreement_payload_free(SilcKeyAgreementPayload payload)
{
if (payload) {
silc_free(payload->hostname);
silc_free(payload);
}
}
/* Returns the hostname in the payload */
char *silc_key_agreement_get_hostname(SilcKeyAgreementPayload payload)
{
return payload->hostname;
}
/* Returns the port in the payload */
SilcUInt32 silc_key_agreement_get_port(SilcKeyAgreementPayload payload)
{
return payload->port;
}
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