1/*-
2 * Copyright (c) 1991, 1993
3 *      Dave Safford.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 */
30
31#include <sys/cdefs.h>
32
33__FBSDID("$FreeBSD$");
34
35/* public key routines */
36/* functions:
37	genkeys(char *public, char *secret)
38	common_key(char *secret, char *public, desData *deskey)
39        pk_encode(char *in, *out, DesData *deskey);
40        pk_decode(char *in, *out, DesData *deskey);
41      where
42	char public[HEXKEYBYTES + 1];
43	char secret[HEXKEYBYTES + 1];
44 */
45
46#include <sys/time.h>
47#include <openssl/des.h>
48#include <fcntl.h>
49#include <stdio.h>
50#include <stdlib.h>
51#include <string.h>
52
53#include "mp.h"
54#include "pk.h"
55
56static void adjust(char keyout[HEXKEYBYTES+1], char *keyin);
57
58/*
59 * Choose top 128 bits of the common key to use as our idea key.
60 */
61static void
62extractideakey(MINT *ck, IdeaData *ideakey)
63{
64        MINT *a;
65        MINT *z;
66        short r;
67        int i;
68        short base = (1 << 8);
69        char *k;
70
71        z = mp_itom(0);
72        a = mp_itom(0);
73        mp_madd(ck, z, a);
74        for (i = 0; i < ((KEYSIZE - 128) / 8); i++) {
75                mp_sdiv(a, base, a, &r);
76        }
77        k = (char *)ideakey;
78        for (i = 0; i < 16; i++) {
79                mp_sdiv(a, base, a, &r);
80                *k++ = r;
81        }
82	mp_mfree(z);
83        mp_mfree(a);
84}
85
86/*
87 * Choose middle 64 bits of the common key to use as our des key, possibly
88 * overwriting the lower order bits by setting parity.
89 */
90static void
91extractdeskey(MINT *ck, DesData *deskey)
92{
93        MINT *a;
94        MINT *z;
95        short r;
96        int i;
97        short base = (1 << 8);
98        char *k;
99
100        z = mp_itom(0);
101        a = mp_itom(0);
102        mp_madd(ck, z, a);
103        for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++) {
104                mp_sdiv(a, base, a, &r);
105        }
106        k = (char *)deskey;
107        for (i = 0; i < 8; i++) {
108                mp_sdiv(a, base, a, &r);
109                *k++ = r;
110        }
111	mp_mfree(z);
112        mp_mfree(a);
113}
114
115/*
116 * get common key from my secret key and his public key
117 */
118void
119common_key(char *xsecret, char *xpublic, IdeaData *ideakey, DesData *deskey)
120{
121        MINT *public;
122        MINT *secret;
123        MINT *common;
124	MINT *modulus = mp_xtom(HEXMODULUS);
125
126        public = mp_xtom(xpublic);
127        secret = mp_xtom(xsecret);
128        common = mp_itom(0);
129        mp_pow(public, secret, modulus, common);
130        extractdeskey(common, deskey);
131        extractideakey(common, ideakey);
132	DES_set_odd_parity(deskey);
133        mp_mfree(common);
134        mp_mfree(secret);
135        mp_mfree(public);
136	mp_mfree(modulus);
137}
138
139/*
140 * Generate a seed
141 */
142static void
143getseed(char *seed, int seedsize)
144{
145	arc4random_buf(seed, seedsize);
146}
147
148/*
149 * Generate a random public/secret key pair
150 */
151void
152genkeys(char *public, char *secret)
153{
154        size_t i;
155
156#       define BASEBITS (8*sizeof(short) - 1)
157#       define BASE (1 << BASEBITS)
158
159        MINT *pk = mp_itom(0);
160        MINT *sk = mp_itom(0);
161        MINT *tmp;
162        MINT *base = mp_itom((short)BASE);
163        MINT *root = mp_itom(PROOT);
164        MINT *modulus = mp_xtom(HEXMODULUS);
165        short r;
166        unsigned short seed[KEYSIZE/BASEBITS + 1];
167        char *xkey;
168
169        getseed((char *)seed, sizeof(seed));
170        for (i = 0; i < KEYSIZE/BASEBITS + 1; i++) {
171                r = seed[i] % BASE;
172                tmp = mp_itom(r);
173                mp_mult(sk, base, sk);
174                mp_madd(sk, tmp, sk);
175                mp_mfree(tmp);
176        }
177        tmp = mp_itom(0);
178        mp_mdiv(sk, modulus, tmp, sk);
179        mp_mfree(tmp);
180        mp_pow(root, sk, modulus, pk);
181        xkey = mp_mtox(sk);
182        adjust(secret, xkey);
183        xkey = mp_mtox(pk);
184        adjust(public, xkey);
185        mp_mfree(sk);
186        mp_mfree(base);
187        mp_mfree(pk);
188        mp_mfree(root);
189        mp_mfree(modulus);
190}
191
192/*
193 * Adjust the input key so that it is 0-filled on the left
194 */
195static void
196adjust(char keyout[HEXKEYBYTES+1], char *keyin)
197{
198        char *p;
199        char *s;
200
201        for (p = keyin; *p; p++)
202                ;
203        for (s = keyout + HEXKEYBYTES; p >= keyin; p--, s--) {
204                *s = *p;
205        }
206        while (s >= keyout) {
207                *s-- = '0';
208        }
209}
210
211static char hextab[17] = "0123456789ABCDEF";
212
213/* given a DES key, cbc encrypt and translate input to terminated hex */
214void
215pk_encode(char *in, char *out, DesData *key)
216{
217	char buf[256];
218	DesData i;
219	DES_key_schedule k;
220	int l,op,deslen;
221
222	memset(&i,0,sizeof(i));
223	memset(buf,0,sizeof(buf));
224	deslen = ((strlen(in) + 7)/8)*8;
225	DES_key_sched(key, &k);
226	DES_cbc_encrypt(in, buf, deslen, &k, &i, DES_ENCRYPT);
227	for (l=0,op=0;l<deslen;l++) {
228		out[op++] = hextab[(buf[l] & 0xf0) >> 4];
229		out[op++] = hextab[(buf[l] & 0x0f)];
230	}
231	out[op] = '\0';
232}
233
234/* given a DES key, translate input from hex and decrypt */
235void
236pk_decode(char *in, char *out, DesData *key)
237{
238	char buf[256];
239	DesData i;
240	DES_key_schedule k;
241	int n1,n2,op;
242	size_t l;
243
244	memset(&i,0,sizeof(i));
245	memset(buf,0,sizeof(buf));
246	for (l=0,op=0;l<strlen(in)/2;l++,op+=2) {
247		if (in[op] > '9')
248			n1 = in[op] - 'A' + 10;
249		else
250			n1 = in[op] - '0';
251		if (in[op+1] > '9')
252			n2 = in[op+1] - 'A' + 10;
253		else
254			n2 = in[op+1] - '0';
255		buf[l] = n1*16 +n2;
256	}
257	DES_key_sched(key, &k);
258	DES_cbc_encrypt(buf, out, strlen(in) / 2, &k, &i, DES_DECRYPT);
259	out[strlen(in)/2] = '\0';
260}
261