Mercurial > dropbear
view gendss.c @ 1011:c635aeeaf25c
Added signature for changeset 1d2d81b1b7c1
author | Matt Johnston <matt@ucc.asn.au> |
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date | Thu, 29 Jan 2015 21:42:01 +0800 |
parents | 220f55d540ae |
children | c45d65392c1a |
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/* * Dropbear - a SSH2 server * * Copyright (c) 2002,2003 Matt Johnston * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #include "includes.h" #include "dbutil.h" #include "signkey.h" #include "bignum.h" #include "dbrandom.h" #include "buffer.h" #include "gendss.h" #include "dss.h" #define QSIZE 20 /* 160 bit */ /* This is just a test */ #ifdef DROPBEAR_DSS static void getq(dropbear_dss_key *key); static void getp(dropbear_dss_key *key, unsigned int size); static void getg(dropbear_dss_key *key); static void getx(dropbear_dss_key *key); static void gety(dropbear_dss_key *key); dropbear_dss_key * gen_dss_priv_key(unsigned int size) { dropbear_dss_key *key; if (size != 1024) { dropbear_exit("DSS keys have a fixed size of 1024 bits"); } key = m_malloc(sizeof(*key)); m_mp_alloc_init_multi(&key->p, &key->q, &key->g, &key->y, &key->x, NULL); getq(key); getp(key, size/8); getg(key); getx(key); gety(key); return key; } static void getq(dropbear_dss_key *key) { char buf[QSIZE]; /* 160 bit prime */ genrandom(buf, QSIZE); buf[0] |= 0x80; /* top bit high */ buf[QSIZE-1] |= 0x01; /* bottom bit high */ bytes_to_mp(key->q, buf, QSIZE); /* 18 rounds are required according to HAC */ if (mp_prime_next_prime(key->q, 18, 0) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } } static void getp(dropbear_dss_key *key, unsigned int size) { DEF_MP_INT(tempX); DEF_MP_INT(tempC); DEF_MP_INT(tempP); DEF_MP_INT(temp2q); int result; unsigned char *buf; m_mp_init_multi(&tempX, &tempC, &tempP, &temp2q, NULL); /* 2*q */ if (mp_mul_d(key->q, 2, &temp2q) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } buf = (unsigned char*)m_malloc(size); result = 0; do { genrandom(buf, size); buf[0] |= 0x80; /* set the top bit high */ /* X is a random mp_int */ bytes_to_mp(&tempX, buf, size); /* C = X mod 2q */ if (mp_mod(&tempX, &temp2q, &tempC) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } /* P = X - (C - 1) = X - C + 1*/ if (mp_sub(&tempX, &tempC, &tempP) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } if (mp_add_d(&tempP, 1, key->p) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } /* now check for prime, 5 rounds is enough according to HAC */ /* result == 1 => p is prime */ if (mp_prime_is_prime(key->p, 5, &result) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } } while (!result); mp_clear_multi(&tempX, &tempC, &tempP, &temp2q, NULL); m_burn(buf, size); m_free(buf); } static void getg(dropbear_dss_key * key) { DEF_MP_INT(div); DEF_MP_INT(h); DEF_MP_INT(val); m_mp_init_multi(&div, &h, &val, NULL); /* get div=(p-1)/q */ if (mp_sub_d(key->p, 1, &val) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } if (mp_div(&val, key->q, &div, NULL) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } /* initialise h=1 */ mp_set(&h, 1); do { /* now keep going with g=h^div mod p, until g > 1 */ if (mp_exptmod(&h, &div, key->p, key->g) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } if (mp_add_d(&h, 1, &h) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } } while (mp_cmp_d(key->g, 1) != MP_GT); mp_clear_multi(&div, &h, &val, NULL); } static void getx(dropbear_dss_key *key) { gen_random_mpint(key->q, key->x); } static void gety(dropbear_dss_key *key) { if (mp_exptmod(key->g, key->x, key->p, key->y) != MP_OKAY) { fprintf(stderr, "DSS key generation failed\n"); exit(1); } } #endif /* DROPBEAR_DSS */