+++ /dev/null
-/* -*-c-*-
- *
- * $Id: dsa-verify.c,v 1.7 2004/04/08 01:36:15 mdw Exp $
- *
- * DSA signature verification
- *
- * (c) 1999 Straylight/Edgeware
- */
-
-/*----- Licensing notice --------------------------------------------------*
- *
- * This file is part of Catacomb.
- *
- * Catacomb is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Library General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or (at your option) any later version.
- *
- * Catacomb 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 Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with Catacomb; if not, write to the Free
- * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
- * MA 02111-1307, USA.
- */
-
-/*----- Header files ------------------------------------------------------*/
-
-#include "dsa.h"
-#include "mp.h"
-#include "mpmont.h"
-
-/*----- Main code ---------------------------------------------------------*/
-
-/* --- @dsa_vrfy@ --- *
- *
- * Arguments: @const dsa_param *dp@ = pointer to DSA parameters
- * @mp *y@ = public verification key
- * @mp *m@ = message which was signed
- * @mp *r, *s@ = the signature
- *
- * Returns: Zero if the signature is a forgery, nonzero if it's valid.
- *
- * Use: Verifies a DSA digital signature.
- */
-
-int dsa_vrfy(const dsa_param *dp, mp *y, mp *m, mp *r, mp *s)
-{
- mpmont pm, qm;
- mp *w;
- mp_expfactor f[2];
- int ok;
-
- /* --- Ensure that all of the signature bits are in range --- */
-
- if ((r->f | s->f) & MP_NEG)
- return (0);
- if (MP_CMP(r, >=, dp->q) || MP_CMP(s, >=, dp->q))
- return (0);
-
- /* --- Set up Montgomery contexts --- */
-
- mpmont_create(&pm, dp->p);
- mpmont_create(&qm, dp->q);
-
- /* --- Compute %$w = s^{-1} \bmod q$% --- */
-
- {
- mp *z = mp_modinv(MP_NEW, s, dp->q);
- w = mpmont_mul(&qm, MP_NEW, z, qm.r2);
- mp_drop(z);
- }
-
- /* --- Compute %$wr$% and %$wm$% --- */
-
- f[0].exp = mpmont_mul(&qm, MP_NEW, w, m);
- f[1].exp = mpmont_mul(&qm, MP_NEW, w, r);
- mp_drop(w);
- mpmont_destroy(&qm);
-
- /* --- Do the exponentiation and take residue mod @q@ --- */
-
- f[0].base = dp->g;
- f[1].base = y;
- w = mpmont_mexp(&pm, MP_NEW, f, 2);
- mp_div(0, &w, w, dp->q);
- ok = MP_EQ(w, r);
-
- /* --- Tidy up --- */
-
- mp_drop(w);
- mp_drop(f[0].exp);
- mp_drop(f[1].exp);
- mpmont_destroy(&pm);
- return (ok);
-}
-
-/* --- @dsa_verify@ --- *
- *
- * Arguments: @const dsa_param *dp@ = pointer to DSA parameters
- * @mp *y@ = public verification key
- * @const void *m@ = pointer to message block
- * @size_t msz@ = size of message block
- * @const void *r@ = pointer to @r@ signature half
- * @size_t rsz@ = size of @r@
- * @const void *s@ = pointer to @s@ signature half
- * @size_t ssz@ = size of @s@
- *
- * Returns: Zero if the signature is a forgery, nonzero if it's valid.
- *
- * Use: Verifies a DSA digital signature.
- */
-
-int dsa_verify(const dsa_param *dp, mp *y,
- const void *m, size_t msz,
- const void *r, size_t rsz,
- const void *s, size_t ssz)
-{
- mp *mm = dsa_h2n(MP_NEW, dp->q, m, msz);
- mp *rm = mp_loadb(MP_NEW, r, rsz);
- mp *sm = mp_loadb(MP_NEW, s, ssz);
- int ok = dsa_vrfy(dp, y, mm, rm, sm);
- mp_drop(mm);
- mp_drop(rm);
- mp_drop(sm);
- return (ok);
-}
-
-/*----- Test rig ----------------------------------------------------------*/
-
-#ifdef TEST_RIG
-
-#include <mLib/testrig.h>
-
-#include "sha.h"
-
-static int verify(int good, dstr *v)
-{
- dsa_param dp;
- mp *y;
- sha_ctx c;
- octet hash[SHA_HASHSZ];
- int ok = 1;
- int rc;
-
- dp.q = *(mp **)v[0].buf;
- dp.p = *(mp **)v[1].buf;
- dp.g = *(mp **)v[2].buf;
- y = *(mp **)v[3].buf;
-
- sha_init(&c);
- sha_hash(&c, v[4].buf, v[4].len);
- sha_done(&c, hash);
-
- rc = dsa_verify(&dp, y, hash, sizeof(hash),
- v[5].buf, v[5].len, v[6].buf, v[6].len);
-
- if (!rc != !good) {
- if (good)
- fputs("\n*** verification failed", stderr);
- else
- fputs("\n*** verification succeeded", stderr);
- fputs("\nq = ", stderr); mp_writefile(dp.q, stderr, 16);
- fputs("\np = ", stderr); mp_writefile(dp.p, stderr, 16);
- fputs("\ng = ", stderr); mp_writefile(dp.g, stderr, 16);
- fputs("\ny = ", stderr); mp_writefile(y, stderr, 16);
- fprintf(stderr, "\nmessage = `%s'", v[4].buf);
- fputs("\nr = ", stderr); type_hex.dump(&v[5], stderr);
- fputs("\ns = ", stderr); type_hex.dump(&v[6], stderr);
- fputc('\n', stderr);
- ok = 0;
- }
-
- mp_drop(dp.p);
- mp_drop(dp.q);
- mp_drop(dp.g);
- mp_drop(y);
- assert(mparena_count(MPARENA_GLOBAL) == 0);
- return (ok);
-}
-
-static int vgood(dstr *v) { return verify(1, v); }
-static int vbad(dstr *v) { return verify(0, v); }
-
-static test_chunk tests[] = {
- { "verify-good", vgood,
- { &type_mp, &type_mp, &type_mp, &type_mp,
- &type_string, &type_hex, &type_hex, 0 } },
- { "verify-bad", vbad,
- { &type_mp, &type_mp, &type_mp, &type_mp,
- &type_string, &type_hex, &type_hex, 0 } },
- { 0, 0, { 0 } }
-};
-
-int main(int argc, char *argv[])
-{
- sub_init();
- test_run(argc, argv, tests, SRCDIR "/tests/dsa");
- return (0);
-}
-
-#endif
-
-/*----- That's all, folks -------------------------------------------------*/
projects / u / mdw / catacomb / blobdiff