/*
-Blind-ID library for user identification using RSA blind signatures
-Copyright (C) 2010 Rudolf Polzer
-
-This library is free software; you can redistribute it and/or
-modify it under the terms of the GNU Lesser General Public
-License as published by the Free Software Foundation; either
-version 2.1 of the License, or (at your option) any later version.
-
-This library 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
-Lesser General Public License for more details.
-
-You should have received a copy of the GNU Lesser General Public
-License along with this library; if not, write to the Free Software
-Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
-*/
+ * FILE: d0_blind_id.c
+ * AUTHOR: Rudolf Polzer - divVerent@xonotic.org
+ *
+ * Copyright (c) 2010, Rudolf Polzer
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTOR(S) ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTOR(S) BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Id$
+ */
#include "d0_blind_id.h"
#include <stdio.h>
#include <string.h>
#include "d0_bignum.h"
-#include "sha1.h"
+#include "sha2.h"
+
+// our SHA is SHA-256
+#define SHA_DIGESTSIZE 32
+const char *sha(const char *in, size_t len)
+{
+ static char h[32];
+ d0_blind_id_util_sha256(h, in, len);
+ return h;
+}
// for zero knowledge, we need multiple instances of schnorr ID scheme... should normally be sequential
// parallel schnorr ID is not provably zero knowledge :(
#define SCHNORR_BITS 20
// probability of cheat: 2^(-bits+1)
-#define SCHNORR_HASHSIZE 3
-// cannot be >= SHA_DIGEST_LENGTH
+#define SCHNORR_HASHSIZE SHA_DIGESTSIZE
+// cannot be >= SHA_DIGESTSIZE
// *8 must be >= SCHNORR_BITS
+// no need to save bits here
#define MSGSIZE 640 // ought to be enough for anyone
d0_bignum_t *schnorr_s;
// public data (player ID public key, this is what the server gets to know)
- d0_bignum_t *schnorr_4_to_s;
- d0_bignum_t *schnorr_4_to_s_signature; // 0 when signature is invalid
+ d0_bignum_t *schnorr_g_to_s;
+ d0_bignum_t *schnorr_H_g_to_s_signature; // 0 when signature is invalid
+ // as hash function H, we get the SHA1 and reinterpret as bignum - yes, it always is < 160 bits
// temp data
d0_bignum_t *rsa_blind_signature_camouflage; // random number blind signature
d0_bignum_t *r; // random number for schnorr ID
- d0_bignum_t *other_4_to_r; // for DH key exchange
+ d0_bignum_t *t; // for DH key exchange
+ d0_bignum_t *g_to_t; // for DH key exchange
+ d0_bignum_t *other_g_to_t; // for DH key exchange
d0_bignum_t *challenge; // challenge
char msghash[SCHNORR_HASHSIZE]; // init hash
#define CHECK(x) do { if(!(x)) goto fail; } while(0)
#define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
+#define MPCHECK(x) do { if(!failed) if(!(x)) failed = 1; } while(0)
+#define MPCHECK_ASSIGN(var, value) do { if(!failed) { d0_bignum_t *val; val = value; if(val) var = val; else failed = 1; } } while(0)
#define USING(x) if(!(ctx->x)) return 0
#define REPLACING(x)
static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
-void d0_blind_id_INITIALIZE(void)
+WARN_UNUSED_RESULT BOOL d0_blind_id_INITIALIZE(void)
{
- d0_bignum_INITIALIZE();
+ CHECK(d0_bignum_INITIALIZE());
CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
CHECK_ASSIGN(one, d0_bignum_int(one, 1));
CHECK_ASSIGN(four, d0_bignum_int(four, 4));
CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
+ return 1;
fail:
- ;
+ return 0;
}
void d0_blind_id_SHUTDOWN(void)
return 0;
}
+WARN_UNUSED_RESULT BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t outbuflen)
+{
+ d0_iobuf_t *out = NULL;
+ static unsigned char convbuf[1024];
+ size_t n, sz;
+
+ n = outbuflen;
+ while(n > SHA_DIGESTSIZE)
+ {
+ sz = (d0_bignum_size(clobberme) + 7) / 8;
+ CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
+ memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
+ outbuf += SHA_DIGESTSIZE;
+ n -= SHA_DIGESTSIZE;
+ CHECK(d0_bignum_add(clobberme, clobberme, one));
+ }
+ sz = (d0_bignum_size(clobberme) + 7) / 8;
+ CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
+ memcpy(outbuf, sha(convbuf, sz), n);
+ return 1;
+
+fail:
+ return 0;
+}
+
void d0_blind_id_clear(d0_blind_id_t *ctx)
{
if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
- if(ctx->schnorr_4_to_s) d0_bignum_free(ctx->schnorr_4_to_s);
- if(ctx->schnorr_4_to_s_signature) d0_bignum_free(ctx->schnorr_4_to_s_signature);
+ if(ctx->schnorr_g_to_s) d0_bignum_free(ctx->schnorr_g_to_s);
+ if(ctx->schnorr_H_g_to_s_signature) d0_bignum_free(ctx->schnorr_H_g_to_s_signature);
if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
if(ctx->r) d0_bignum_free(ctx->r);
if(ctx->challenge) d0_bignum_free(ctx->challenge);
- if(ctx->other_4_to_r) d0_bignum_free(ctx->other_4_to_r);
+ if(ctx->t) d0_bignum_free(ctx->t);
+ if(ctx->g_to_t) d0_bignum_free(ctx->g_to_t);
+ if(ctx->other_g_to_t) d0_bignum_free(ctx->other_g_to_t);
memset(ctx, 0, sizeof(*ctx));
}
if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
- if(src->schnorr_4_to_s) CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mov(NULL, ctx->schnorr_G));
- if(src->schnorr_4_to_s_signature) CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_mov(NULL, src->schnorr_4_to_s_signature));
+ if(src->schnorr_g_to_s) CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mov(NULL, src->schnorr_g_to_s));
+ if(src->schnorr_H_g_to_s_signature) CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_mov(NULL, src->schnorr_H_g_to_s_signature));
if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
- if(src->other_4_to_r) CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mov(NULL, src->other_4_to_r));
+ if(src->t) CHECK_ASSIGN(ctx->t, d0_bignum_mov(NULL, src->t));
+ if(src->g_to_t) CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mov(NULL, src->g_to_t));
+ if(src->other_g_to_t) CHECK_ASSIGN(ctx->other_g_to_t, d0_bignum_mov(NULL, src->other_g_to_t));
memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
ctx->msglen = src->msglen;
memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
{
// temps: temp0 = order
USING(schnorr_G);
- REPLACING(schnorr_s); REPLACING(schnorr_4_to_s);
+ REPLACING(schnorr_s); REPLACING(schnorr_g_to_s);
CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
- CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mod_pow(ctx->schnorr_4_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
- CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_zero(ctx->schnorr_4_to_s_signature));
+ CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mod_pow(ctx->schnorr_g_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
+ CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
return 1;
fail:
WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
{
d0_iobuf_t *out = NULL;
+ static unsigned char convbuf[2048], shabuf[2048];
+ size_t sz;
// temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
- USING(rsa_n); USING(rsa_e); USING(schnorr_4_to_s);
+ USING(rsa_n); USING(rsa_e); USING(schnorr_g_to_s);
REPLACING(rsa_blind_signature_camouflage);
out = d0_iobuf_open_write(outbuf, *outbuflen);
CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
- CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_4_to_s, temp0, ctx->rsa_n));
+
+ // we will actually sign HA(4^s) to prevent a malleability attack!
+ CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
+ sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
+ if(sz > sizeof(shabuf))
+ sz = sizeof(shabuf);
+ CHECK(d0_longhash_destructive(temp2, shabuf, sz));
+ CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
+
+ // hash complete
+ CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
CHECK(d0_iobuf_write_bignum(out, temp1));
return d0_iobuf_close(out, outbuflen);
// temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
USING(rsa_blind_signature_camouflage); USING(rsa_n);
- REPLACING(schnorr_4_to_s_signature);
+ REPLACING(schnorr_H_g_to_s_signature);
in = d0_iobuf_open_read(inbuf, inbuflen);
CHECK(d0_iobuf_read_bignum(in, temp0));
CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
- CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_4_to_s_signature, temp0, temp1, ctx->rsa_n));
+ CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_H_g_to_s_signature, temp0, temp1, ctx->rsa_n));
return d0_iobuf_close(in, NULL);
{
d0_iobuf_t *in = NULL;
- REPLACING(schnorr_s); REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
+ REPLACING(schnorr_s); REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
in = d0_iobuf_open_read(inbuf, inbuflen);
CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
- CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
- CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
+ CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
+ CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
return d0_iobuf_close(in, NULL);
{
d0_iobuf_t *in = NULL;
- REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
+ REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
in = d0_iobuf_open_read(inbuf, inbuflen);
- CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
- CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
+ CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
+ CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
return d0_iobuf_close(in, NULL);
{
d0_iobuf_t *out = NULL;
- USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
+ USING(schnorr_s); USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
out = d0_iobuf_open_write(outbuf, *outbuflen);
CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
- CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
- CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
return d0_iobuf_close(out, outbuflen);
{
d0_iobuf_t *out = NULL;
- USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
+ USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
out = d0_iobuf_open_write(outbuf, *outbuflen);
- CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
- CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
return d0_iobuf_close(out, outbuflen);
static unsigned char convbuf[1024];
d0_iobuf_t *conv = NULL;
size_t sz = 0;
+ BOOL failed = 0;
// temps: temp0 order, temp0 4^r
if(is_first)
{
- USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
+ USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
}
USING(schnorr_G);
- REPLACING(r);
+ REPLACING(r); REPLACING(t); REPLACING(g_to_t);
out = d0_iobuf_open_write(outbuf, *outbuflen);
// send ID
if(send_modulus)
CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
- CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
- CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
}
// start schnorr ID scheme
// generate random number r; x = g^r; send hash of x, remember r, forget x
CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
- CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
+ //CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
+
+ // initialize Signed Diffie Hellmann
+ // we already have the group order in temp1
+ CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
+ // can we SOMEHOW do this with just one mod_pow?
+
+ MPCHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
+ MPCHECK_ASSIGN(ctx->g_to_t, d0_bignum_mod_pow(ctx->g_to_t, four, ctx->t, ctx->schnorr_G));
+ CHECK(!failed);
// hash it, hash it, everybody hash it
conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
CHECK(d0_iobuf_write_bignum(conv, temp0));
+ CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
CHECK(d0_iobuf_write_packet(conv, msg, msglen));
CHECK(d0_iobuf_write_bignum(conv, temp0));
+ CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
d0_iobuf_close(conv, &sz);
conv = NULL;
CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
{
d0_iobuf_t *in = NULL;
d0_iobuf_t *out = NULL;
+ static unsigned char shabuf[2048];
+ size_t sz;
// temps: temp0 order, temp0 signature check
if(is_first)
{
- REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
+ REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
if(recv_modulus)
REPLACING(schnorr_G);
else
}
else
{
- USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
+ USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
USING(schnorr_G);
}
USING(rsa_e); USING(rsa_n);
- REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r);
+ REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r); REPLACING(t);
in = d0_iobuf_open_read(inbuf, inbuflen);
out = d0_iobuf_open_write(outbuf, *outbuflen);
CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
}
- CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
- CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, zero) > 0);
- CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, ctx->schnorr_G) < 0);
- CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
- CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero) >= 0);
- CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, ctx->rsa_n) < 0);
+ CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
+ CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
+ CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
+ CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
+ CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
+ CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
// check signature of key (t = k^d, so, t^challenge = k)
- CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_4_to_s_signature, ctx->rsa_e, ctx->rsa_n));
- if(d0_bignum_cmp(temp0, ctx->schnorr_4_to_s))
+ CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
+
+ // we will actually sign SHA(4^s) to prevent a malleability attack!
+ CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
+ sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
+ if(sz > sizeof(shabuf))
+ sz = sizeof(shabuf);
+ CHECK(d0_longhash_destructive(temp2, shabuf, sz));
+ CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
+
+ // + 7 / 8 is too large, so let's mod it
+ CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
+
+ // hash complete
+ if(d0_bignum_cmp(temp0, temp1))
{
// accept the key anyway, but mark as failed signature! will later return 0 in status
- CHECK(d0_bignum_zero(ctx->schnorr_4_to_s_signature));
+ CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
}
}
// send challenge
CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
-
CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
- // Diffie Hellmann
+ // Diffie Hellmann send
CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
- CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
- CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
+ CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
+ CHECK(d0_bignum_mod_pow(temp0, four, ctx->t, ctx->schnorr_G));
CHECK(d0_iobuf_write_bignum(out, temp0));
if(status)
- *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
+ *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
d0_iobuf_close(in, NULL);
return d0_iobuf_close(out, outbuflen);
d0_iobuf_t *out = NULL;
// temps: 0 order, 1 prod, 2 y, 3 challenge
- REPLACING(other_4_to_r);
- USING(schnorr_G); USING(schnorr_s); USING(r);
+ REPLACING(other_g_to_t); REPLACING(t);
+ USING(schnorr_G); USING(schnorr_s); USING(r); USING(g_to_t);
in = d0_iobuf_open_read(inbuf, inbuflen);
out = d0_iobuf_open_write(outbuf, *outbuflen);
CHECK(d0_bignum_cmp(temp3, zero) >= 0);
CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
- // Diffie Hellmann
- CHECK_ASSIGN(ctx->other_4_to_r, d0_iobuf_read_bignum(in, ctx->other_4_to_r));
- CHECK(d0_bignum_cmp(ctx->other_4_to_r, zero) > 0);
- CHECK(d0_bignum_cmp(ctx->other_4_to_r, ctx->schnorr_G) < 0);
-
// send response for schnorr ID scheme
// i.challenge. r + ctx->schnorr_s * temp3
CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
CHECK(d0_iobuf_write_bignum(out, temp2));
+ // Diffie Hellmann recv
+ CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
+ CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
+ CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
+ // Diffie Hellmann send
+ CHECK(d0_iobuf_write_bignum(out, ctx->g_to_t));
+
d0_iobuf_close(in, NULL);
return d0_iobuf_close(out, outbuflen);
// temps: 0 y 1 order
USING(challenge); USING(schnorr_G);
- REPLACING(other_4_to_r);
+ REPLACING(other_g_to_t);
in = d0_iobuf_open_read(inbuf, inbuflen);
CHECK(d0_bignum_cmp(temp0, temp1) < 0);
// verify schnorr ID scheme
- // we need 4^temp0 (g^s)^-challenge
- CHECK(d0_bignum_neg(temp1, ctx->challenge));
- CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_4_to_s, temp1, ctx->schnorr_G));
+ // we need 4^r = 4^temp0 (g^s)^-challenge
+ CHECK(d0_bignum_mod_inv(temp1, ctx->schnorr_g_to_s, ctx->schnorr_G));
+ CHECK(d0_bignum_mod_pow(temp2, temp1, ctx->challenge, ctx->schnorr_G));
CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
- CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mod_mul(ctx->other_4_to_r, temp1, temp2, ctx->schnorr_G));
- // hash must be equal to msghash
+ CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G));
+
+ // Diffie Hellmann recv
+ CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
+ CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
+ CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
// hash it, hash it, everybody hash it
conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
- CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
+ CHECK(d0_iobuf_write_bignum(conv, temp3));
+ CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
- CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
+ CHECK(d0_iobuf_write_bignum(conv, temp3));
+ CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
d0_iobuf_close(conv, &sz);
conv = NULL;
if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
}
if(status)
- *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
+ *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
if(ctx->msglen <= *msglen)
memcpy(msg, ctx->msg, ctx->msglen);
return 0;
}
+WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_generate_missing_signature(d0_blind_id_t *ctx)
+{
+ size_t sz;
+ static unsigned char shabuf[2048];
+
+ REPLACING(schnorr_H_g_to_s_signature);
+ USING(schnorr_g_to_s); USING(rsa_d); USING(rsa_n);
+
+ // we will actually sign SHA(4^s) to prevent a malleability attack!
+ CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
+ sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
+ if(sz > sizeof(shabuf))
+ sz = sizeof(shabuf);
+ CHECK(d0_longhash_destructive(temp2, shabuf, sz));
+ CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
+
+ // + 7 / 8 is too large, so let's mod it
+ CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
+ CHECK(d0_bignum_mod_pow(ctx->schnorr_H_g_to_s_signature, temp1, ctx->rsa_d, ctx->rsa_n));
+ return 1;
+
+fail:
+ return 0;
+}
+
WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
{
d0_iobuf_t *out = NULL;
d0_iobuf_t *conv = NULL;
size_t sz, n;
- USING(schnorr_4_to_s);
+ USING(rsa_n);
+ USING(rsa_e);
+ USING(schnorr_g_to_s);
out = d0_iobuf_open_write(outbuf, *outbuflen);
conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
- CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_4_to_s));
+ CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
+ CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
+ CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_g_to_s));
CHECK(d0_iobuf_close(conv, &sz));
conv = NULL;
BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
{
- d0_iobuf_t *out = NULL;
- static unsigned char convbuf[1024];
- d0_iobuf_t *conv = NULL;
- size_t n, sz;
-
- USING(r); USING(other_4_to_r); USING(schnorr_G);
-
- out = d0_iobuf_open_write(outbuf, *outbuflen);
- conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+ USING(t); USING(other_g_to_t); USING(schnorr_G);
// temps: temp0 result
- CHECK(d0_bignum_mod_pow(temp0, ctx->other_4_to_r, ctx->r, ctx->schnorr_G));
- CHECK(d0_iobuf_write_bignum(conv, temp0));
- CHECK(d0_iobuf_close(conv, &sz));
- conv = NULL;
-
- n = *outbuflen;
- if(n > SHA_DIGESTSIZE)
- n = SHA_DIGESTSIZE;
- CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
-
- return d0_iobuf_close(out, outbuflen);
+ CHECK(d0_bignum_mod_pow(temp0, ctx->other_g_to_t, ctx->t, ctx->schnorr_G));
+ return d0_longhash_destructive(temp0, outbuf, *outbuflen);
fail:
- if(conv)
- d0_iobuf_close(conv, &sz);
- d0_iobuf_close(out, outbuflen);
return 0;
}
d0_blind_id_clear(a);
d0_free(a);
}
+
+void d0_blind_id_util_sha256(char *out, const char *in, size_t n)
+{
+ SHA256_CTX context;
+ SHA256_Init(&context);
+ SHA256_Update(&context, (const unsigned char *) in, n);
+ return SHA256_Final((unsigned char *) out, &context);
+}
projects / xonotic / d0_blind_id.git / blobdiff