2 * Copyright (c) 1991, 1993
3 * Dave Safford. All rights reserved.
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30 * $FreeBSD: src/crypto/telnet/libtelnet/pk.c,v 1.2.2.4 2002/08/24 07:28:35 nsayer Exp $
33 /* public key routines */
35 genkeys(char *public, char *secret)
36 common_key(char *secret, char *public, desData *deskey)
37 pk_encode(char *in, *out, DesData *deskey);
38 pk_decode(char *in, *out, DesData *deskey);
40 char public[HEXKEYBYTES + 1];
41 char secret[HEXKEYBYTES + 1];
51 #include <openssl/bn.h>
52 #include <openssl/crypto.h>
53 #include <openssl/des.h>
54 #include <openssl/err.h>
58 static void adjust(char keyout[HEXKEYBYTES+1], char *keyin);
61 * Choose top 128 bits of the common key to use as our idea key.
64 extractideakey(BIGNUM *ck, IdeaData *ideakey)
68 BN_ULONG r, base = (1 << 8);
71 if ((z = BN_new()) == NULL)
72 errx(1, "could not create BIGNUM");
74 if ((a = BN_new()) == NULL)
75 errx(1, "could not create BIGNUM");
78 for (i = 0; i < ((KEYSIZE - 128) / 8); i++) {
79 r = BN_div_word(a, base);
82 for (i = 0; i < 16; i++) {
83 r = BN_div_word(a, base);
91 * Choose middle 64 bits of the common key to use as our des key, possibly
92 * overwriting the lower order bits by setting parity.
95 extractdeskey(BIGNUM *ck, DesData *deskey)
99 BN_ULONG r, base = (1 << 8);
102 if ((z = BN_new()) == NULL)
103 errx(1, "could not create BIGNUM");
105 if ((a = BN_new()) == NULL)
106 errx(1, "could not create BIGNUM");
109 for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++) {
110 r = BN_div_word(a, base);
113 for (i = 0; i < 8; i++) {
114 r = BN_div_word(a, base);
122 * get common key from my secret key and his public key
125 common_key(char *xsecret, char *xpublic, IdeaData *ideakey, DesData *deskey)
127 BIGNUM *public, *secret, *common, *modulus;
130 if ((ctx = BN_CTX_new()) == NULL)
131 errx(1, "could not create BN_CTX");
133 if (BN_hex2bn(&modulus, HEXMODULUS) == 0)
134 errx(1, "could not convert modulus");
136 if (BN_hex2bn(&public, xpublic) == 0)
137 errx(1, "could not convert public");
139 if (BN_hex2bn(&secret, xsecret) == 0)
140 errx(1, "could not convert secret");
142 if ((common = BN_new()) == NULL)
143 errx(1, "could not create BIGNUM");
145 BN_mod_exp(common, public, secret, modulus, ctx);
146 extractdeskey(common, deskey);
147 extractideakey(common, ideakey);
148 des_set_odd_parity(deskey);
160 getseed(char *seed, int seedsize)
164 for (i = 0; i < seedsize; i++) {
165 seed[i] = arc4random() & 0xff;
174 if ((n = BN_new()) == NULL)
175 errx(1, "could not create BIGNUM: %s",
176 ERR_error_string(ERR_get_error(), 0));
179 BN_add_word(n, (u_long)i);
181 BN_sub_word(n, (u_long)(-i));
186 * Generate a random public/secret key pair
189 genkeys(char *public, char *secret)
191 #define BASEBITS (8*sizeof (short) - 1)
192 #define BASE (short)(1 << BASEBITS)
196 unsigned short seed[KEYSIZE/BASEBITS + 1];
200 BIGNUM *pk, *sk, *tmp, *base, *root, *modulus;
208 if (BN_hex2bn(&modulus, HEXMODULUS) == 0)
209 errx(1, "could not convert modulus to BIGNUM: %s",
210 ERR_error_string(ERR_get_error(), 0));
212 if ((ctx = BN_CTX_new()) == NULL)
213 errx(1, "could not create BN_CTX: %s",
214 ERR_error_string(ERR_get_error(), 0));
216 getseed((char *)seed, sizeof (seed));
217 for (i = 0; i < KEYSIZE/BASEBITS + 1; i++) {
221 BN_mul(sk, base, sk, ctx);
225 BN_div(tmp, sk, sk, modulus, ctx);
226 BN_mod_exp(pk, root, sk, modulus, ctx);
228 if ((xkey = BN_bn2hex(sk)) == NULL)
229 errx(1, "could convert sk to hex: %s",
230 ERR_error_string(ERR_get_error(), 0));
231 adjust(secret, xkey);
234 if ((xkey = BN_bn2hex(pk)) == NULL)
235 errx(1, "could convert pk to hex: %s",
236 ERR_error_string(ERR_get_error(), 0));
237 adjust(public, xkey);
249 * Adjust the input key so that it is 0-filled on the left
252 adjust(char keyout[HEXKEYBYTES+1], char *keyin)
257 for (p = keyin; *p; p++)
259 for (s = keyout + HEXKEYBYTES; p >= keyin; p--, s--) {
262 while (s >= keyout) {
267 static char hextab[17] = "0123456789ABCDEF";
269 /* given a DES key, cbc encrypt and translate input to terminated hex */
271 pk_encode(char *in, char *out, DesData *key)
278 memset(&i,0,sizeof(i));
279 memset(buf,0,sizeof(buf));
280 deslen = ((strlen(in) + 7)/8)*8;
281 des_key_sched(key, k);
282 des_cbc_encrypt(in,buf,deslen, k,&i,DES_ENCRYPT);
283 for (l=0,op=0;l<deslen;l++) {
284 out[op++] = hextab[(buf[l] & 0xf0) >> 4];
285 out[op++] = hextab[(buf[l] & 0x0f)];
290 /* given a DES key, translate input from hex and decrypt */
292 pk_decode(char *in, char *out, DesData *key)
300 memset(&i,0,sizeof(i));
301 memset(buf,0,sizeof(buf));
302 for (l=0,op=0;l<strlen(in)/2;l++,op+=2) {
304 n1 = in[op] - 'A' + 10;
308 n2 = in[op+1] - 'A' + 10;
313 des_key_sched(key, k);
314 des_cbc_encrypt(buf,out,strlen(in)/2, k,&i,DES_DECRYPT);
315 out[strlen(in)/2] = '\0';