2 Blind-ID library for user identification using RSA blind signatures
3 Copyright (C) 2010 Rudolf Polzer
5 This library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 This library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with this library; if not, write to the Free Software
17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 #include "d0_blind_id.h"
24 #include "d0_bignum.h"
27 // for zero knowledge, we need multiple instances of schnorr ID scheme... should normally be sequential
28 // parallel schnorr ID is not provably zero knowledge :(
29 // (evil verifier can know all questions in advance, so sequential is disadvantage for him)
30 // we'll just live with a 1:1048576 chance of cheating, and support reauthenticating
32 #define SCHNORR_BITS 20
33 // probability of cheat: 2^(-bits+1)
35 #define SCHNORR_HASHSIZE 3
36 // cannot be >= SHA_DIGEST_LENGTH
37 // *8 must be >= SCHNORR_BITS
39 #define MSGSIZE 640 // ought to be enough for anyone
43 // signing (Xonotic pub and priv key)
44 d0_bignum_t *rsa_n, *rsa_e, *rsa_d;
46 // public data (Schnorr ID)
47 d0_bignum_t *schnorr_G;
49 // private data (player ID private key)
50 d0_bignum_t *schnorr_s;
52 // public data (player ID public key, this is what the server gets to know)
53 d0_bignum_t *schnorr_4_to_s;
54 d0_bignum_t *schnorr_4_to_s_signature; // 0 when signature is invalid
57 d0_bignum_t *rn; // random number blind signature
58 d0_bignum_t *r; // random number for schnorr ID
59 char xnbh[SCHNORR_HASHSIZE]; // init hash
60 d0_bignum_t *e; // challenge
61 char msg[MSGSIZE]; // message
62 size_t msglen; // message length
63 d0_bignum_t *other_4_to_r; // for DH key exchange
66 #define CHECK(x) do { if(!(x)) goto fail; } while(0)
67 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
69 #define USING(x) if(!(ctx->x)) return 0
72 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
74 void d0_blind_id_INITIALIZE(void)
76 d0_bignum_INITIALIZE();
77 CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
78 CHECK_ASSIGN(one, d0_bignum_int(one, 1));
79 CHECK_ASSIGN(four, d0_bignum_int(four, 4));
80 CHECK_ASSIGN(temp0, d0_bignum_int(temp0, 0));
81 CHECK_ASSIGN(temp1, d0_bignum_int(temp1, 0));
82 CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
83 CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
84 CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
89 void d0_blind_id_SHUTDOWN(void)
94 d0_bignum_free(temp0);
95 d0_bignum_free(temp1);
96 d0_bignum_free(temp2);
97 d0_bignum_free(temp3);
98 d0_bignum_free(temp4);
103 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
105 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
106 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
112 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
114 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
115 CHECK(d0_bignum_add(G, G, one));
121 BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
128 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
129 if(d0_bignum_isprime(temp0, 0) == 0)
131 CHECK(d0_dl_get_from_order(G, temp0));
132 if(d0_bignum_isprime(G, 10) == 0)
134 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
143 BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *e, d0_bignum_t *d, d0_bignum_t *n)
145 // uses temp0 to temp4
148 int pb = (size + 1)/2;
156 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
157 if(d0_bignum_isprime(temp0, 10) == 0)
159 CHECK(d0_bignum_sub(temp2, temp0, one));
160 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, e));
161 if(!d0_bignum_cmp(temp4, one))
170 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
171 if(!d0_bignum_cmp(temp1, temp0))
177 if(d0_bignum_isprime(temp1, 10) == 0)
179 CHECK(d0_bignum_sub(temp3, temp1, one));
180 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, e));
181 if(!d0_bignum_cmp(temp4, one))
189 CHECK(d0_bignum_mul(n, temp0, temp1));
191 // d = e^-1 mod (temp0-1)(temp1-1)
192 CHECK(d0_bignum_mul(temp0, temp2, temp3));
193 CHECK(d0_bignum_mod_inv(d, e, temp0));
199 void d0_blind_id_clear(d0_blind_id_t *ctx)
201 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
202 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
203 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
204 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
205 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
206 if(ctx->schnorr_4_to_s) d0_bignum_free(ctx->schnorr_4_to_s);
207 if(ctx->schnorr_4_to_s_signature) d0_bignum_free(ctx->schnorr_4_to_s_signature);
208 if(ctx->rn) d0_bignum_free(ctx->rn);
209 if(ctx->r) d0_bignum_free(ctx->r);
210 if(ctx->e) d0_bignum_free(ctx->e);
211 if(ctx->other_4_to_r) d0_bignum_free(ctx->other_4_to_r);
212 memset(ctx, 0, sizeof(*ctx));
215 void d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
217 d0_blind_id_clear(ctx);
218 if(src->rsa_n) ctx->rsa_n = d0_bignum_mov(NULL, src->rsa_n);
219 if(src->rsa_e) ctx->rsa_e = d0_bignum_mov(NULL, src->rsa_e);
220 if(src->rsa_d) ctx->rsa_d = d0_bignum_mov(NULL, src->rsa_d);
221 if(src->schnorr_G) ctx->schnorr_G = d0_bignum_mov(NULL, src->schnorr_G);
222 if(src->schnorr_s) ctx->schnorr_s = d0_bignum_mov(NULL, src->schnorr_s);
223 if(src->schnorr_4_to_s) ctx->schnorr_4_to_s = d0_bignum_mov(NULL, ctx->schnorr_G);
224 if(src->schnorr_4_to_s_signature) ctx->schnorr_4_to_s_signature = d0_bignum_mov(NULL, src->schnorr_4_to_s_signature);
225 if(src->rn) ctx->rn = d0_bignum_mov(NULL, src->rn);
226 if(src->r) ctx->r = d0_bignum_mov(NULL, src->r);
227 if(src->e) ctx->e = d0_bignum_mov(NULL, src->e);
228 if(src->other_4_to_r) ctx->other_4_to_r = d0_bignum_mov(NULL, src->other_4_to_r);
229 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
230 ctx->msglen = src->msglen;
231 memcpy(ctx->xnbh, src->xnbh, sizeof(ctx->xnbh));
234 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
236 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
238 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
239 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
240 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
241 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
247 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
249 d0_iobuf_t *in = NULL;
251 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
253 in = d0_iobuf_open_read(inbuf, inbuflen);
255 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
256 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
257 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
258 return d0_iobuf_close(in, NULL);
261 d0_iobuf_close(in, NULL);
265 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
267 d0_iobuf_t *in = NULL;
269 REPLACING(rsa_n); REPLACING(rsa_e);
271 in = d0_iobuf_open_read(inbuf, inbuflen);
272 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
273 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
274 return d0_iobuf_close(in, NULL);
277 d0_iobuf_close(in, NULL);
281 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
283 d0_iobuf_t *out = NULL;
285 USING(rsa_n); USING(rsa_e); USING(rsa_d);
287 out = d0_iobuf_open_write(outbuf, *outbuflen);
288 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
289 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
290 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
291 return d0_iobuf_close(out, outbuflen);
294 d0_iobuf_close(out, outbuflen);
298 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
300 d0_iobuf_t *out = NULL;
302 USING(rsa_n); USING(rsa_e);
304 out = d0_iobuf_open_write(outbuf, *outbuflen);
305 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
306 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
307 return d0_iobuf_close(out, outbuflen);
310 if(!d0_iobuf_close(out, outbuflen))
315 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
318 REPLACING(schnorr_G);
320 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
321 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
327 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
329 d0_iobuf_t *in = NULL;
331 REPLACING(schnorr_G);
333 in = d0_iobuf_open_read(inbuf, inbuflen);
334 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
335 return d0_iobuf_close(in, NULL);
338 d0_iobuf_close(in, NULL);
342 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
344 d0_iobuf_t *out = NULL;
348 out = d0_iobuf_open_write(outbuf, *outbuflen);
349 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
350 return d0_iobuf_close(out, outbuflen);
353 d0_iobuf_close(out, outbuflen);
357 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
359 // temps: temp0 = order
361 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s);
363 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
364 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
365 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mod_pow(ctx->schnorr_4_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
366 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_zero(ctx->schnorr_4_to_s_signature));
373 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
375 d0_iobuf_t *out = NULL;
377 // temps: temp0 rn^e, temp1 (4^s)*rn^e
378 USING(rsa_n); USING(rsa_e); USING(schnorr_4_to_s);
381 out = d0_iobuf_open_write(outbuf, *outbuflen);
383 CHECK_ASSIGN(ctx->rn, d0_bignum_rand_bit_atmost(ctx->rn, d0_bignum_size(ctx->rsa_n)));
384 CHECK(d0_bignum_mod_pow(temp0, ctx->rn, ctx->rsa_e, ctx->rsa_n));
385 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_4_to_s, temp0, ctx->rsa_n));
386 CHECK(d0_iobuf_write_bignum(out, temp1));
387 return d0_iobuf_close(out, outbuflen);
390 d0_iobuf_close(out, outbuflen);
394 WARN_UNUSED_RESULT BOOL d0_blind_id_answer_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen)
396 d0_iobuf_t *in = NULL;
397 d0_iobuf_t *out = NULL;
399 // temps: temp0 input, temp1 temp0^d
400 USING(rsa_d); USING(rsa_n);
402 in = d0_iobuf_open_read(inbuf, inbuflen);
403 out = d0_iobuf_open_write(outbuf, *outbuflen);
405 CHECK(d0_iobuf_read_bignum(in, temp0));
406 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
407 CHECK(d0_iobuf_write_bignum(out, temp1));
409 d0_iobuf_close(in, NULL);
410 return d0_iobuf_close(out, outbuflen);
413 d0_iobuf_close(in, NULL);
414 d0_iobuf_close(out, outbuflen);
418 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
420 d0_iobuf_t *in = NULL;
422 // temps: temp0 input, temp1 rn^-1
423 USING(rn); USING(rsa_n);
424 REPLACING(schnorr_4_to_s_signature);
426 in = d0_iobuf_open_read(inbuf, inbuflen);
428 CHECK(d0_iobuf_read_bignum(in, temp0));
429 CHECK(d0_bignum_mod_inv(temp1, ctx->rn, ctx->rsa_n));
430 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_4_to_s_signature, temp0, temp1, ctx->rsa_n));
432 return d0_iobuf_close(in, NULL);
435 d0_iobuf_close(in, NULL);
439 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
441 d0_iobuf_t *in = NULL;
443 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
445 in = d0_iobuf_open_read(inbuf, inbuflen);
447 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
448 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
449 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
451 return d0_iobuf_close(in, NULL);
454 d0_iobuf_close(in, NULL);
458 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
460 d0_iobuf_t *in = NULL;
462 REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
464 in = d0_iobuf_open_read(inbuf, inbuflen);
466 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
467 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
469 return d0_iobuf_close(in, NULL);
472 d0_iobuf_close(in, NULL);
476 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
478 d0_iobuf_t *out = NULL;
480 USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
482 out = d0_iobuf_open_write(outbuf, *outbuflen);
484 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
485 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
486 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
488 return d0_iobuf_close(out, outbuflen);
491 d0_iobuf_close(out, outbuflen);
495 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
497 d0_iobuf_t *out = NULL;
499 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
501 out = d0_iobuf_open_write(outbuf, *outbuflen);
503 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
504 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
506 return d0_iobuf_close(out, outbuflen);
509 d0_iobuf_close(out, outbuflen);
513 WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_id_t *ctx, BOOL is_first, BOOL send_modulus, char *msg, size_t msglen, char *outbuf, size_t *outbuflen)
515 // first run: send 4^s, 4^s signature
516 // 1. get random r, send HASH(4^r)
518 d0_iobuf_t *out = NULL;
519 static unsigned char convbuf[1024];
520 d0_iobuf_t *conv = NULL;
523 // temps: temp0 order, temp0 4^r
526 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
531 out = d0_iobuf_open_write(outbuf, *outbuflen);
537 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
538 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
539 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
542 // start schnorr ID scheme
543 // generate random number r; x = g^r; send hash of x, remember r, forget x
544 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
545 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
546 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
548 // hash it, hash it, everybody hash it
549 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
550 CHECK(d0_iobuf_write_bignum(conv, temp0));
551 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
552 CHECK(d0_iobuf_write_bignum(conv, temp0));
553 d0_iobuf_close(conv, &sz);
555 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
556 CHECK(d0_iobuf_write_packet(out, msg, msglen));
558 return d0_iobuf_close(out, outbuflen);
561 d0_iobuf_close(out, outbuflen);
565 WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_blind_id_t *ctx, BOOL is_first, BOOL recv_modulus, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen, BOOL *status)
566 // first run: get 4^s, 4^s signature
569 // 3. send challenge e of SCHNORR_BITS
571 d0_iobuf_t *in = NULL;
572 d0_iobuf_t *out = NULL;
574 // temps: temp0 order, temp0 signature check
577 REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
579 REPLACING(schnorr_G);
585 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
588 USING(rsa_e); USING(rsa_n);
589 REPLACING(e); REPLACING(msg); REPLACING(msglen); REPLACING(xnbh); REPLACING(r);
591 in = d0_iobuf_open_read(inbuf, inbuflen);
592 out = d0_iobuf_open_write(outbuf, *outbuflen);
598 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
599 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
600 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
602 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
603 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, zero) > 0);
604 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, ctx->schnorr_G) < 0);
605 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
606 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero) >= 0);
607 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, ctx->rsa_n) < 0);
609 // check signature of key (t = k^d, so, t^e = k)
610 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_4_to_s_signature, ctx->rsa_e, ctx->rsa_n));
611 if(d0_bignum_cmp(temp0, ctx->schnorr_4_to_s))
613 // accept the key anyway, but mark as failed signature! will later return 0 in status
614 CHECK(d0_bignum_zero(ctx->schnorr_4_to_s_signature));
618 CHECK(d0_iobuf_read_raw(in, ctx->xnbh, SCHNORR_HASHSIZE));
619 ctx->msglen = MSGSIZE;
620 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
623 CHECK_ASSIGN(ctx->e, d0_bignum_rand_bit_atmost(ctx->e, SCHNORR_BITS));
625 CHECK(d0_iobuf_write_bignum(out, ctx->e));
628 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
629 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
630 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
631 CHECK(d0_iobuf_write_bignum(out, temp0));
634 *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
636 d0_iobuf_close(in, NULL);
637 return d0_iobuf_close(out, outbuflen);
640 d0_iobuf_close(in, NULL);
641 d0_iobuf_close(out, outbuflen);
645 WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_response(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen)
646 // 1. read challenge e of SCHNORR_BITS
647 // 2. reply with r + s * e mod order
649 d0_iobuf_t *in = NULL;
650 d0_iobuf_t *out = NULL;
652 // temps: 0 order, 1 prod, 2 y, 3 e
653 REPLACING(other_4_to_r);
654 USING(schnorr_G); USING(schnorr_s); USING(r);
656 in = d0_iobuf_open_read(inbuf, inbuflen);
657 out = d0_iobuf_open_write(outbuf, *outbuflen);
659 CHECK(d0_iobuf_read_bignum(in, temp3));
660 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
661 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
664 CHECK_ASSIGN(ctx->other_4_to_r, d0_iobuf_read_bignum(in, ctx->other_4_to_r));
665 CHECK(d0_bignum_cmp(ctx->other_4_to_r, zero) > 0);
666 CHECK(d0_bignum_cmp(ctx->other_4_to_r, ctx->schnorr_G) < 0);
668 // send response for schnorr ID scheme
669 // i.e. r + ctx->schnorr_s * temp3
670 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
671 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
672 CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
673 CHECK(d0_iobuf_write_bignum(out, temp2));
675 d0_iobuf_close(in, NULL);
676 return d0_iobuf_close(out, outbuflen);
679 d0_iobuf_close(in, NULL);
680 d0_iobuf_close(out, outbuflen);
684 WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *msg, size_t *msglen, BOOL *status)
685 // 1. read y = r + s * e mod order
686 // 2. verify: g^y (g^s)^-e = g^(r+s*e-s*e) = g^r
687 // (check using H(g^r) which we know)
689 d0_iobuf_t *in = NULL;
690 static unsigned char convbuf[1024];
691 d0_iobuf_t *conv = NULL;
694 // temps: 0 y 1 order
695 USING(e); USING(schnorr_G);
696 REPLACING(other_4_to_r);
698 in = d0_iobuf_open_read(inbuf, inbuflen);
700 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
701 CHECK(d0_iobuf_read_bignum(in, temp0));
702 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
703 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
705 // verify schnorr ID scheme
706 // we need 4^temp0 (g^s)^-e
707 CHECK(d0_bignum_neg(temp1, ctx->e));
708 CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_4_to_s, temp1, ctx->schnorr_G));
709 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
710 CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mod_mul(ctx->other_4_to_r, temp1, temp2, ctx->schnorr_G));
711 // hash must be equal to xnbh
713 // hash it, hash it, everybody hash it
714 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
715 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
716 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
717 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
718 d0_iobuf_close(conv, &sz);
720 if(memcmp(sha(convbuf, sz), ctx->xnbh, SCHNORR_HASHSIZE))
722 // FAIL (not owned by player)
727 *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
729 if(ctx->msglen <= *msglen)
730 memcpy(msg, ctx->msg, ctx->msglen);
732 memcpy(msg, ctx->msg, *msglen);
733 *msglen = ctx->msglen;
735 d0_iobuf_close(in, NULL);
739 d0_iobuf_close(in, NULL);
743 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
745 d0_iobuf_t *out = NULL;
746 static unsigned char convbuf[1024];
747 d0_iobuf_t *conv = NULL;
750 USING(schnorr_4_to_s);
752 out = d0_iobuf_open_write(outbuf, *outbuflen);
753 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
755 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_4_to_s));
756 CHECK(d0_iobuf_close(conv, &sz));
759 n = (*outbuflen / 4) * 3;
760 if(n > SHA_DIGESTSIZE)
762 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
763 CHECK(d0_iobuf_conv_base64_out(out));
765 return d0_iobuf_close(out, outbuflen);
769 d0_iobuf_close(conv, &sz);
770 d0_iobuf_close(out, outbuflen);
774 BOOL d0_blind_id_sessionkey_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
776 d0_iobuf_t *out = NULL;
777 static unsigned char convbuf[1024];
778 d0_iobuf_t *conv = NULL;
781 USING(r); USING(other_4_to_r); USING(schnorr_G);
783 out = d0_iobuf_open_write(outbuf, *outbuflen);
784 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
786 // temps: temp0 result
787 CHECK(d0_bignum_mod_pow(temp0, ctx->other_4_to_r, ctx->r, ctx->schnorr_G));
788 CHECK(d0_iobuf_write_bignum(conv, temp0));
789 CHECK(d0_iobuf_close(conv, &sz));
793 if(n > SHA_DIGESTSIZE)
795 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
797 return d0_iobuf_close(out, outbuflen);
801 d0_iobuf_close(conv, &sz);
802 d0_iobuf_close(out, outbuflen);
806 d0_blind_id_t *d0_blind_id_new(void)
808 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
809 memset(b, 0, sizeof(*b));
813 void d0_blind_id_free(d0_blind_id_t *a)
815 d0_blind_id_clear(a);