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fishlim: Add /keyx for DH1080 key exchange

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Losely based upon work from PR #1440

Fixes #653
This commit is contained in:
Patrick Griffis 2016-08-28 21:18:44 -04:00
parent 65abf5c532
commit dba19a961b
6 changed files with 416 additions and 20 deletions
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4
plugins/fishlim/Makefile.am
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@ -1,9 +1,9 @@
EXTRA_DIST = INSTALL LICENSE fish.h irc.h keystore.h plugin_hexchat.h
EXTRA_DIST = INSTALL LICENSE fish.h irc.h keystore.h plugin_hexchat.h dh1080.h
libdir = $(hexchatlibdir)
lib_LTLIBRARIES = fishlim.la
fishlim_la_SOURCES = fish.c irc.c keystore.c plugin_hexchat.c
fishlim_la_SOURCES = fish.c irc.c keystore.c plugin_hexchat.c dh1080.c
fishlim_la_LDFLAGS = $(PLUGIN_LDFLAGS) -module
fishlim_la_LIBADD = $(GLIB_LIBS) $(OPENSSL_LIBS)
fishlim_la_CPPFLAGS = -I$(top_srcdir)/src/common

209
plugins/fishlim/dh1080.c Normal file
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@ -0,0 +1,209 @@
/* HexChat
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
/*
* For Diffie-Hellman key-exchange a 1080bit germain prime is used, the
* generator g=2 renders a field Fp from 1 to p-1. Therefore breaking it
* means to solve a discrete logarithm problem with no less than 1080bit.
*
* Base64 format is used to send the public keys over IRC.
*
* The calculated secret key is hashed with SHA-256, the result is converted
* to base64 for final use with blowfish.
*/
#include "dh1080.h"
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/sha.h>
#include <string.h>
#include <glib.h>
#define DH1080_PRIME_BITS 1080
#define DH1080_PRIME_BYTES 135
#define SHA256_DIGEST_LENGTH 32
#define B64ABC "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
#define MEMZERO(x) memset(x, 0x00, (sizeof(x)/sizeof(*x)) )
/* All clients must use the same prime number to be able to keyx */
static const guchar prime1080[DH1080_PRIME_BYTES] =
{
0xFB, 0xE1, 0x02, 0x2E, 0x23, 0xD2, 0x13, 0xE8, 0xAC, 0xFA, 0x9A, 0xE8, 0xB9, 0xDF, 0xAD, 0xA3, 0xEA,
0x6B, 0x7A, 0xC7, 0xA7, 0xB7, 0xE9, 0x5A, 0xB5, 0xEB, 0x2D, 0xF8, 0x58, 0x92, 0x1F, 0xEA, 0xDE, 0x95,
0xE6, 0xAC, 0x7B, 0xE7, 0xDE, 0x6A, 0xDB, 0xAB, 0x8A, 0x78, 0x3E, 0x7A, 0xF7, 0xA7, 0xFA, 0x6A, 0x2B,
0x7B, 0xEB, 0x1E, 0x72, 0xEA, 0xE2, 0xB7, 0x2F, 0x9F, 0xA2, 0xBF, 0xB2, 0xA2, 0xEF, 0xBE, 0xFA, 0xC8,
0x68, 0xBA, 0xDB, 0x3E, 0x82, 0x8F, 0xA8, 0xBA, 0xDF, 0xAD, 0xA3, 0xE4, 0xCC, 0x1B, 0xE7, 0xE8, 0xAF,
0xE8, 0x5E, 0x96, 0x98, 0xA7, 0x83, 0xEB, 0x68, 0xFA, 0x07, 0xA7, 0x7A, 0xB6, 0xAD, 0x7B, 0xEB, 0x61,
0x8A, 0xCF, 0x9C, 0xA2, 0x89, 0x7E, 0xB2, 0x8A, 0x61, 0x89, 0xEF, 0xA0, 0x7A, 0xB9, 0x9A, 0x8A, 0x7F,
0xA9, 0xAE, 0x29, 0x9E, 0xFA, 0x7B, 0xA6, 0x6D, 0xEA, 0xFE, 0xFB, 0xEF, 0xBF, 0x0B, 0x7D, 0x8B
};
static DH *g_dh;
int
dh1080_init (void)
{
g_return_val_if_fail (g_dh == NULL, 0);
if ((g_dh = DH_new()))
{
int codes;
g_dh->p = BN_bin2bn (prime1080, DH1080_PRIME_BYTES, NULL);
g_dh->g = BN_new ();
g_assert (g_dh->p != NULL && g_dh->g != NULL);
BN_set_word(g_dh->g, 2);
if (DH_check (g_dh, &codes))
return codes == 0;
}
return 0;
}
void
dh1080_deinit (void)
{
g_clear_pointer (&g_dh, DH_free);
}
static inline int
DH_verifyPubKey (BIGNUM *pk)
{
int codes;
return DH_check_pub_key (g_dh, pk, &codes) && codes == 0;
}
static guchar *
dh1080_decode_b64 (const char *data, gsize *out_len)
{
GString *str = g_string_new (data);
guchar *ret;
if (str->len % 4 == 1 && str->str[str->len - 1] == 'A')
g_string_truncate (str, str->len - 1);
while (str->len % 4 != 0)
g_string_append_c (str, '=');
ret = g_base64_decode_inplace (str->str, out_len);
g_string_free (str, FALSE);
return ret;
}
static char *
dh1080_encode_b64 (const guchar *data, gsize data_len)
{
char *ret = g_base64_encode (data, data_len);
char *p;
if (!(p = strchr (ret, '=')))
{
char *new_ret = g_new(char, strlen(ret) + 2);
strcpy (new_ret, ret);
strcat (new_ret, "A");
g_free (ret);
ret = new_ret;
}
else
{
*p = '\0';
}
return ret;
}
int
dh1080_generate_key (char **priv_key, char **pub_key)
{
guchar buf[DH1080_PRIME_BYTES];
int len;
DH *dh;
g_assert (priv_key != NULL);
g_assert (pub_key != NULL);
dh = DHparams_dup (g_dh);
if (!dh)
return 0;
if (!DH_generate_key (dh))
{
DH_free (dh);
return 0;
}
MEMZERO (buf);
len = BN_bn2bin (dh->priv_key, buf);
*priv_key = dh1080_encode_b64 (buf, len);
MEMZERO (buf);
len = BN_bn2bin(dh->pub_key, buf);
*pub_key = dh1080_encode_b64 (buf, len);
OPENSSL_cleanse (buf, sizeof (buf));
DH_free (dh);
return 1;
}
int
dh1080_compute_key (const char *priv_key, const char *pub_key, char **secret_key)
{
char *pub_key_data;
gsize pub_key_len;
BIGNUM *pk;
DH *dh;
g_assert (secret_key != NULL);
/* Verify base64 strings */
if (strspn (priv_key, B64ABC) != strlen (priv_key)
|| strspn (pub_key, B64ABC) != strlen (pub_key))
return 0;
dh = DHparams_dup (g_dh);
pub_key_data = dh1080_decode_b64 (pub_key, &pub_key_len);
pk = BN_bin2bn (pub_key_data, pub_key_len, NULL);
if (DH_verifyPubKey (pk))
{
guchar shared_key[DH1080_PRIME_BYTES] = { 0 };
guchar sha256[SHA256_DIGEST_LENGTH] = { 0 };
char *priv_key_data;
gsize priv_key_len;
int shared_len;
priv_key_data = dh1080_decode_b64 (priv_key, &priv_key_len);
dh->priv_key = BN_bin2bn(priv_key_data, priv_key_len, NULL);
shared_len = DH_compute_key (shared_key, pk, dh);
SHA256(shared_key, shared_len, sha256);
*secret_key = dh1080_encode_b64 (sha256, sizeof(sha256));
OPENSSL_cleanse (priv_key_data, priv_key_len);
g_free (priv_key_data);
}
BN_free (pk);
DH_free (dh);
g_free (pub_key_data);
return 1;
}

24
plugins/fishlim/dh1080.h Normal file
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@ -0,0 +1,24 @@
/* HexChat
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
#pragma once
int dh1080_generate_key (char **, char **);
int dh1080_compute_key (const char *, const char *, char **);
int dh1080_init (void);
void dh1080_deinit (void);

3
plugins/fishlim/fishlim.vcxproj
View File

@ -53,13 +53,14 @@
<None Include="fishlim.def" />
</ItemGroup>
<ItemGroup>
<ClInclude Include="bool.h" />
<ClInclude Include="dh1080.h" />
<ClInclude Include="fish.h" />
<ClInclude Include="irc.h" />
<ClInclude Include="keystore.h" />
<ClInclude Include="plugin_hexchat.h" />
</ItemGroup>
<ItemGroup>
<ClCompile Include="dh1080.c" />
<ClCompile Include="fish.c" />
<ClCompile Include="irc.c" />
<ClCompile Include="keystore.c" />

2
plugins/fishlim/irc.c
View File

@ -50,7 +50,9 @@ gboolean irc_parse_message(const char *words[],
if (command) *command = words[w];
w++;
if (parameters_offset)
*parameters_offset = w;
return TRUE;
}

160
plugins/fishlim/plugin_hexchat.c
View File

@ -32,6 +32,7 @@
#define HEXCHAT_MAX_WORDS 32
#include "fish.h"
#include "dh1080.h"
#include "keystore.h"
#include "irc.h"
@ -41,8 +42,11 @@ static const char plugin_version[] = "0.0.17";
static const char usage_setkey[] = "Usage: SETKEY [<nick or #channel>] <password>, sets the key for a channel or nick";
static const char usage_delkey[] = "Usage: DELKEY <nick or #channel>, deletes the key for a channel or nick";
static const char usage_keyx[] = "Usage: KEYX [<nick>], performs DH1080 key-exchange with <nick>";
static hexchat_plugin *ph;
static GHashTable *pending_exchanges;
/**
@ -58,6 +62,38 @@ gchar *get_config_filename(void) {
return filename_fs;
}
static inline gboolean irc_is_query (const char *name) {
const char *chantypes = hexchat_list_str (ph, NULL, "chantypes");
return strchr (chantypes, name[0]) == NULL;
}
static hexchat_context *find_context_on_network (const char *name) {
hexchat_list *channels;
hexchat_context *ret = NULL;
int id;
if (hexchat_get_prefs(ph, "id", NULL, &id) != 2)
return NULL;
channels = hexchat_list_get(ph, "channels");
if (!channels)
return NULL;
while (hexchat_list_next(ph, channels)) {
int chan_id = hexchat_list_int(ph, channels, "id");
const char *chan_name = hexchat_list_str(ph, channels, "channel");
if (chan_id == id && chan_name && hexchat_nickcmp (ph, chan_name, name) == 0) {
ret = (hexchat_context*)hexchat_list_str(ph, channels, "context");
break;
}
};
hexchat_list_free(ph, channels);
return ret;
}
int irc_nick_cmp(const char *a, const char *b) {
return hexchat_nickcmp (ph, a, b);
}
@ -191,6 +227,83 @@ static int handle_incoming(char *word[], char *word_eol[], hexchat_event_attrs *
return HEXCHAT_EAT_NONE;
}
static int handle_keyx_notice(char *word[], char *word_eol[], void *userdata) {
const char *dh_message = word[4];
const char *dh_pubkey = word[5];
hexchat_context *query_ctx;
const char *prefix;
gboolean cbc;
char *sender, *secret_key, *priv_key = NULL;
if (!*dh_message || !*dh_pubkey || strlen(dh_pubkey) != 181)
return HEXCHAT_EAT_NONE;
if (!irc_parse_message((const char**)word, &prefix, NULL, NULL) || !prefix)
return HEXCHAT_EAT_NONE;
sender = irc_prefix_get_nick(prefix);
query_ctx = find_context_on_network(sender);
if (query_ctx)
hexchat_set_context(ph, query_ctx);
dh_message++; /* : prefix */
if (*dh_message == '+' || *dh_message == '-')
dh_message++; /* identify-msg */
cbc = g_strcmp0 (word[6], "CBC") == 0;
if (!strcmp(dh_message, "DH1080_INIT")) {
char *pub_key;
if (cbc) {
hexchat_print(ph, "Recieved key exchange for CBC mode which is not supported.");
goto cleanup;
}
hexchat_printf(ph, "Received public key from %s, sending mine...", sender);
if (dh1080_generate_key(&priv_key, &pub_key)) {
hexchat_commandf(ph, "quote NOTICE %s :DH1080_FINISH %s", sender, pub_key);
g_free(pub_key);
} else {
hexchat_print(ph, "Failed to generate keys");
goto cleanup;
}
} else if (!strcmp (dh_message, "DH1080_FINISH")) {
char *sender_lower = g_ascii_strdown(sender, -1);
/* FIXME: Properly respect irc casing */
priv_key = g_hash_table_lookup(pending_exchanges, sender_lower);
g_hash_table_steal(pending_exchanges, sender_lower);
g_free(sender_lower);
if (cbc) {
hexchat_print(ph, "Recieved key exchange for CBC mode which is not supported.");
goto cleanup;
}
if (!priv_key) {
hexchat_printf(ph, "Recieved a key exchange response for unknown user: %s", sender);
goto cleanup;
}
} else {
/* Regular notice */
g_free(sender);
return HEXCHAT_EAT_NONE;
}
if (dh1080_compute_key(priv_key, dh_pubkey, &secret_key)) {
keystore_store_key(sender, secret_key);
hexchat_printf(ph, "Stored new key for %s", sender);
g_free(secret_key);
} else {
hexchat_print(ph, "Failed to create secret key!");
}
cleanup:
g_free(sender);
g_free(priv_key);
return HEXCHAT_EAT_ALL;
}
/**
* Command handler for /setkey
*/
@ -248,6 +361,43 @@ static int handle_delkey(char *word[], char *word_eol[], void *userdata) {
return HEXCHAT_EAT_HEXCHAT;
}
static int handle_keyx(char *word[], char *word_eol[], void *userdata) {
const char *target = word[2];
hexchat_context *query_ctx = NULL;
char *pub_key, *priv_key;
int ctx_type;
if (*target)
query_ctx = find_context_on_network(target);
else {
target = hexchat_get_info(ph, "channel");
query_ctx = hexchat_get_context (ph);
}
if (query_ctx) {
hexchat_set_context(ph, query_ctx);
ctx_type = hexchat_list_int(ph, NULL, "type");
}
if ((query_ctx && ctx_type != 3) || (!query_ctx && !irc_is_query(target))) {
hexchat_print(ph, "You can only exchange keys with individuals");
return HEXCHAT_EAT_ALL;
}
if (dh1080_generate_key(&priv_key, &pub_key)) {
g_hash_table_replace (pending_exchanges, g_ascii_strdown(target, -1), priv_key);
hexchat_commandf(ph, "quote NOTICE %s :DH1080_INIT %s", target, pub_key);
hexchat_printf(ph, "Sent public key to %s, waiting for reply...", target);
g_free(pub_key);
} else {
hexchat_print(ph, "Failed to generate keys");
}
return HEXCHAT_EAT_ALL;
}
/**
* Returns the plugin name version information.
*/
@ -276,21 +426,31 @@ int hexchat_plugin_init(hexchat_plugin *plugin_handle,
/* Register commands */
hexchat_hook_command(ph, "SETKEY", HEXCHAT_PRI_NORM, handle_setkey, usage_setkey, NULL);
hexchat_hook_command(ph, "DELKEY", HEXCHAT_PRI_NORM, handle_delkey, usage_delkey, NULL);
hexchat_hook_command(ph, "KEYX", HEXCHAT_PRI_NORM, handle_keyx, usage_keyx, NULL);
/* Add handlers */
hexchat_hook_command(ph, "", HEXCHAT_PRI_NORM, handle_outgoing, NULL, NULL);
hexchat_hook_server(ph, "NOTICE", HEXCHAT_PRI_HIGHEST, handle_keyx_notice, NULL);
hexchat_hook_server_attrs(ph, "NOTICE", HEXCHAT_PRI_NORM, handle_incoming, NULL);
hexchat_hook_server_attrs(ph, "PRIVMSG", HEXCHAT_PRI_NORM, handle_incoming, NULL);
/* hexchat_hook_server(ph, "RAW LINE", HEXCHAT_PRI_NORM, handle_debug, NULL); */
hexchat_hook_server_attrs(ph, "TOPIC", HEXCHAT_PRI_NORM, handle_incoming, NULL);
hexchat_hook_server_attrs(ph, "332", HEXCHAT_PRI_NORM, handle_incoming, NULL);
if (!dh1080_init())
return 0;
pending_exchanges = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, g_free);
hexchat_printf(ph, "%s plugin loaded\n", plugin_name);
/* Return success */
return 1;
}
int hexchat_plugin_deinit(void) {
g_clear_pointer(&pending_exchanges, g_hash_table_destroy);
dh1080_deinit();
hexchat_printf(ph, "%s plugin unloaded\n", plugin_name);
return 1;
}