X-Git-Url: http://de.git.xonotic.org/?a=blobdiff_plain;f=d0_blind_id.c;h=bc9db70bf00436fcadeccf26d66e84879a970075;hb=aa15778b6ef970cb4c6a483d8ec2c353f73de4c8;hp=ae60b035c9dadfb321e56e95b7fe14fbba829a9c;hpb=042d22ba10260c0f543aae1a979e9b721bf713f1;p=xonotic%2Fd0_blind_id.git diff --git a/d0_blind_id.c b/d0_blind_id.c index ae60b03..bc9db70 100644 --- a/d0_blind_id.c +++ b/d0_blind_id.c @@ -1,28 +1,53 @@ /* -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. + * + * $Format:commit %H$ + * $Id$ + */ #include "d0_blind_id.h" #include #include #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 :( @@ -32,9 +57,10 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA #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 @@ -50,15 +76,17 @@ struct d0_blind_id_s 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_H_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 @@ -68,15 +96,17 @@ struct d0_blind_id_s #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)); @@ -85,8 +115,9 @@ void d0_blind_id_INITIALIZE(void) 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) @@ -258,6 +289,31 @@ fail: 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); @@ -265,12 +321,14 @@ void d0_blind_id_clear(d0_blind_id_t *ctx) 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_H_4_to_s_signature) d0_bignum_free(ctx->schnorr_H_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)); } @@ -282,12 +340,14 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t 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, src->schnorr_4_to_s)); - if(src->schnorr_H_4_to_s_signature) CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_bignum_mov(NULL, src->schnorr_H_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)); @@ -464,13 +524,12 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx { // 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(d0_bignum_shl(temp1, ctx->schnorr_G, -1)); 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_H_4_to_s_signature, d0_bignum_zero(ctx->schnorr_H_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: @@ -480,21 +539,26 @@ 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]; + 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)); - // we will actually sign SHA(4^s) to prevent a malleability attack! - sz = (d0_bignum_size(ctx->schnorr_4_to_s) + 7) / 8; - CHECK(d0_bignum_export_unsigned(ctx->schnorr_4_to_s, convbuf, sz) >= 0); - CHECK(d0_bignum_import_unsigned(temp2, sha(convbuf, sz), SHA_DIGESTSIZE)); + + // 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)); @@ -535,13 +599,13 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1 USING(rsa_blind_signature_camouflage); USING(rsa_n); - REPLACING(schnorr_H_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_H_4_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_H_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); @@ -588,13 +652,13 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const ch { d0_iobuf_t *in = NULL; - REPLACING(schnorr_s); REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_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_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_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); @@ -607,12 +671,12 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const cha { d0_iobuf_t *in = NULL; - REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_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_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_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); @@ -625,13 +689,13 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, c { d0_iobuf_t *out = NULL; - USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_H_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_H_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); @@ -644,12 +708,12 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, ch { d0_iobuf_t *out = NULL; - USING(schnorr_4_to_s); USING(schnorr_H_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_H_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); @@ -667,14 +731,15 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_ 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_H_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); @@ -683,21 +748,32 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_ // 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_H_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); @@ -718,13 +794,13 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_bl { d0_iobuf_t *in = NULL; d0_iobuf_t *out = NULL; - static unsigned char convbuf[2048]; + static unsigned char shabuf[2048]; size_t sz; // temps: temp0 order, temp0 signature check if(is_first) { - REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_4_to_s_signature); + REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature); if(recv_modulus) REPLACING(schnorr_G); else @@ -732,11 +808,11 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_bl } else { - USING(schnorr_4_to_s); USING(schnorr_H_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); @@ -749,25 +825,32 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_bl 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_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_4_to_s_signature)); - CHECK(d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, zero) >= 0); - CHECK(d0_bignum_cmp(ctx->schnorr_H_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_H_4_to_s_signature, ctx->rsa_e, ctx->rsa_n)); + 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! - sz = (d0_bignum_size(ctx->schnorr_4_to_s) + 7) / 8; - CHECK(d0_bignum_export_unsigned(ctx->schnorr_4_to_s, convbuf, sz) >= 0); - CHECK(d0_bignum_import_unsigned(temp2, sha(convbuf, sz), SHA_DIGESTSIZE)); + 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_H_4_to_s_signature)); + CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature)); } } @@ -777,17 +860,16 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_bl // 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_H_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); @@ -806,8 +888,8 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_response(d0_bli 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); @@ -816,11 +898,6 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_response(d0_bli 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)); @@ -828,6 +905,13 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_response(d0_bli 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); @@ -849,7 +933,7 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind // 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); @@ -859,18 +943,24 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind 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)) @@ -880,7 +970,7 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind } if(status) - *status = !!d0_bignum_cmp(ctx->schnorr_H_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); @@ -896,6 +986,31 @@ fail: 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; @@ -903,12 +1018,16 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t 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; @@ -929,33 +1048,13 @@ fail: 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; } @@ -971,3 +1070,11 @@ void d0_blind_id_free(d0_blind_id_t *a) 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); +}