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 *rsa_blind_signature_camouflage; // random number blind signature
59 d0_bignum_t *r; // random number for schnorr ID
60 d0_bignum_t *other_4_to_r; // for DH key exchange
61 d0_bignum_t *challenge; // challenge
63 char msghash[SCHNORR_HASHSIZE]; // init hash
64 char msg[MSGSIZE]; // message
65 size_t msglen; // message length
68 #define CHECK(x) do { if(!(x)) goto fail; } while(0)
69 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
71 #define USING(x) if(!(ctx->x)) return 0
74 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
76 void d0_blind_id_INITIALIZE(void)
78 d0_bignum_INITIALIZE();
79 CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
80 CHECK_ASSIGN(one, d0_bignum_int(one, 1));
81 CHECK_ASSIGN(four, d0_bignum_int(four, 4));
82 CHECK_ASSIGN(temp0, d0_bignum_int(temp0, 0));
83 CHECK_ASSIGN(temp1, d0_bignum_int(temp1, 0));
84 CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
85 CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
86 CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
91 void d0_blind_id_SHUTDOWN(void)
96 d0_bignum_free(temp0);
97 d0_bignum_free(temp1);
98 d0_bignum_free(temp2);
99 d0_bignum_free(temp3);
100 d0_bignum_free(temp4);
101 d0_bignum_SHUTDOWN();
105 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
107 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
108 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
114 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
116 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
117 CHECK(d0_bignum_add(G, G, one));
123 BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
130 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
131 if(d0_bignum_isprime(temp0, 0) == 0)
133 CHECK(d0_dl_get_from_order(G, temp0));
134 if(d0_bignum_isprime(G, 10) == 0)
136 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
145 BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
147 // uses temp0 to temp4
150 int pb = (size + 1)/2;
158 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
159 if(d0_bignum_isprime(temp0, 10) == 0)
161 CHECK(d0_bignum_sub(temp2, temp0, one));
162 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
163 if(!d0_bignum_cmp(temp4, one))
172 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
173 if(!d0_bignum_cmp(temp1, temp0))
179 if(d0_bignum_isprime(temp1, 10) == 0)
181 CHECK(d0_bignum_sub(temp3, temp1, one));
182 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
183 if(!d0_bignum_cmp(temp4, one))
191 CHECK(d0_bignum_mul(n, temp0, temp1));
193 // d = challenge^-1 mod (temp0-1)(temp1-1)
194 CHECK(d0_bignum_mul(temp0, temp2, temp3));
195 CHECK(d0_bignum_mod_inv(d, challenge, temp0));
201 BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
203 // uses temp0 to temp4
206 int pb = (size + 1)/2;
214 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
215 if(d0_bignum_isprime(temp0, 10) == 0)
217 CHECK(d0_bignum_sub(temp2, temp0, one));
218 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
219 if(!d0_bignum_cmp(temp4, one))
228 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
229 if(!d0_bignum_cmp(temp1, temp0))
237 CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
238 if(reject(ctx, pass))
241 if(d0_bignum_isprime(temp1, 10) == 0)
243 CHECK(d0_bignum_sub(temp3, temp1, one));
244 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
245 if(!d0_bignum_cmp(temp4, one))
252 // ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
253 CHECK(d0_bignum_mul(temp0, temp2, temp3));
254 CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
260 void d0_blind_id_clear(d0_blind_id_t *ctx)
262 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
263 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
264 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
265 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
266 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
267 if(ctx->schnorr_4_to_s) d0_bignum_free(ctx->schnorr_4_to_s);
268 if(ctx->schnorr_4_to_s_signature) d0_bignum_free(ctx->schnorr_4_to_s_signature);
269 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
270 if(ctx->r) d0_bignum_free(ctx->r);
271 if(ctx->challenge) d0_bignum_free(ctx->challenge);
272 if(ctx->other_4_to_r) d0_bignum_free(ctx->other_4_to_r);
273 memset(ctx, 0, sizeof(*ctx));
276 WARN_UNUSED_RESULT BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
278 d0_blind_id_clear(ctx);
279 if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
280 if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
281 if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
282 if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
283 if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
284 if(src->schnorr_4_to_s) CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mov(NULL, ctx->schnorr_G));
285 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));
286 if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
287 if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
288 if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
289 if(src->other_4_to_r) CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mov(NULL, src->other_4_to_r));
290 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
291 ctx->msglen = src->msglen;
292 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
295 d0_blind_id_clear(ctx);
299 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key_fastreject(d0_blind_id_t *ctx, int k, d0_fastreject_function reject, void *pass)
301 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
303 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
304 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
305 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
307 CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
309 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
315 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
317 return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
320 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
322 d0_iobuf_t *in = NULL;
324 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
326 in = d0_iobuf_open_read(inbuf, inbuflen);
328 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
329 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
330 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
331 return d0_iobuf_close(in, NULL);
334 d0_iobuf_close(in, NULL);
338 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
340 d0_iobuf_t *in = NULL;
342 REPLACING(rsa_n); REPLACING(rsa_e);
344 in = d0_iobuf_open_read(inbuf, inbuflen);
345 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
346 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
347 return d0_iobuf_close(in, NULL);
350 d0_iobuf_close(in, NULL);
354 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
356 d0_iobuf_t *out = NULL;
358 USING(rsa_n); USING(rsa_e); USING(rsa_d);
360 out = d0_iobuf_open_write(outbuf, *outbuflen);
361 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
362 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
363 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
364 return d0_iobuf_close(out, outbuflen);
367 d0_iobuf_close(out, outbuflen);
371 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
373 d0_iobuf_t *out = NULL;
375 USING(rsa_n); USING(rsa_e);
377 out = d0_iobuf_open_write(outbuf, *outbuflen);
378 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
379 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
380 return d0_iobuf_close(out, outbuflen);
383 if(!d0_iobuf_close(out, outbuflen))
388 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
390 d0_iobuf_t *out = NULL;
391 static unsigned char convbuf[2048];
392 d0_iobuf_t *conv = NULL;
395 USING(rsa_n); USING(rsa_e);
397 out = d0_iobuf_open_write(outbuf, *outbuflen);
398 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
400 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
401 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
402 CHECK(d0_iobuf_close(conv, &sz));
405 n = (*outbuflen / 4) * 3;
406 if(n > SHA_DIGESTSIZE)
408 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
409 CHECK(d0_iobuf_conv_base64_out(out));
411 return d0_iobuf_close(out, outbuflen);
415 d0_iobuf_close(conv, &sz);
416 d0_iobuf_close(out, outbuflen);
420 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
423 REPLACING(schnorr_G);
425 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
426 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
432 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
434 d0_iobuf_t *in = NULL;
436 REPLACING(schnorr_G);
438 in = d0_iobuf_open_read(inbuf, inbuflen);
439 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
440 return d0_iobuf_close(in, NULL);
443 d0_iobuf_close(in, NULL);
447 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
449 d0_iobuf_t *out = NULL;
453 out = d0_iobuf_open_write(outbuf, *outbuflen);
454 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
455 return d0_iobuf_close(out, outbuflen);
458 d0_iobuf_close(out, outbuflen);
462 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
464 // temps: temp0 = order
466 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s);
468 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
469 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
470 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mod_pow(ctx->schnorr_4_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
471 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_zero(ctx->schnorr_4_to_s_signature));
478 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
480 d0_iobuf_t *out = NULL;
482 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
483 USING(rsa_n); USING(rsa_e); USING(schnorr_4_to_s);
484 REPLACING(rsa_blind_signature_camouflage);
486 out = d0_iobuf_open_write(outbuf, *outbuflen);
488 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
489 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
490 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_4_to_s, temp0, ctx->rsa_n));
491 CHECK(d0_iobuf_write_bignum(out, temp1));
492 return d0_iobuf_close(out, outbuflen);
495 d0_iobuf_close(out, outbuflen);
499 WARN_UNUSED_RESULT BOOL d0_blind_id_answer_private_id_request(const d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen)
501 d0_iobuf_t *in = NULL;
502 d0_iobuf_t *out = NULL;
504 // temps: temp0 input, temp1 temp0^d
505 USING(rsa_d); USING(rsa_n);
507 in = d0_iobuf_open_read(inbuf, inbuflen);
508 out = d0_iobuf_open_write(outbuf, *outbuflen);
510 CHECK(d0_iobuf_read_bignum(in, temp0));
511 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
512 CHECK(d0_iobuf_write_bignum(out, temp1));
514 d0_iobuf_close(in, NULL);
515 return d0_iobuf_close(out, outbuflen);
518 d0_iobuf_close(in, NULL);
519 d0_iobuf_close(out, outbuflen);
523 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
525 d0_iobuf_t *in = NULL;
527 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
528 USING(rsa_blind_signature_camouflage); USING(rsa_n);
529 REPLACING(schnorr_4_to_s_signature);
531 in = d0_iobuf_open_read(inbuf, inbuflen);
533 CHECK(d0_iobuf_read_bignum(in, temp0));
534 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
535 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_4_to_s_signature, temp0, temp1, ctx->rsa_n));
537 return d0_iobuf_close(in, NULL);
540 d0_iobuf_close(in, NULL);
544 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
546 d0_iobuf_t *in = NULL;
548 REPLACING(rsa_blind_signature_camouflage);
550 in = d0_iobuf_open_read(inbuf, inbuflen);
552 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
554 return d0_iobuf_close(in, NULL);
557 d0_iobuf_close(in, NULL);
561 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_request_camouflage(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
563 d0_iobuf_t *out = NULL;
565 USING(rsa_blind_signature_camouflage);
567 out = d0_iobuf_open_write(outbuf, *outbuflen);
569 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
571 return d0_iobuf_close(out, outbuflen);
574 d0_iobuf_close(out, outbuflen);
578 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
580 d0_iobuf_t *in = NULL;
582 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
584 in = d0_iobuf_open_read(inbuf, inbuflen);
586 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
587 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
588 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
590 return d0_iobuf_close(in, NULL);
593 d0_iobuf_close(in, NULL);
597 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
599 d0_iobuf_t *in = NULL;
601 REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
603 in = d0_iobuf_open_read(inbuf, inbuflen);
605 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
606 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
608 return d0_iobuf_close(in, NULL);
611 d0_iobuf_close(in, NULL);
615 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
617 d0_iobuf_t *out = NULL;
619 USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
621 out = d0_iobuf_open_write(outbuf, *outbuflen);
623 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
624 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
625 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
627 return d0_iobuf_close(out, outbuflen);
630 d0_iobuf_close(out, outbuflen);
634 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
636 d0_iobuf_t *out = NULL;
638 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
640 out = d0_iobuf_open_write(outbuf, *outbuflen);
642 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
643 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
645 return d0_iobuf_close(out, outbuflen);
648 d0_iobuf_close(out, outbuflen);
652 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)
654 // first run: send 4^s, 4^s signature
655 // 1. get random r, send HASH(4^r)
657 d0_iobuf_t *out = NULL;
658 static unsigned char convbuf[1024];
659 d0_iobuf_t *conv = NULL;
662 // temps: temp0 order, temp0 4^r
665 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
670 out = d0_iobuf_open_write(outbuf, *outbuflen);
676 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
677 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
678 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
681 // start schnorr ID scheme
682 // generate random number r; x = g^r; send hash of x, remember r, forget x
683 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
684 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
685 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
687 // hash it, hash it, everybody hash it
688 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
689 CHECK(d0_iobuf_write_bignum(conv, temp0));
690 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
691 CHECK(d0_iobuf_write_bignum(conv, temp0));
692 d0_iobuf_close(conv, &sz);
694 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
695 CHECK(d0_iobuf_write_packet(out, msg, msglen));
697 return d0_iobuf_close(out, outbuflen);
700 d0_iobuf_close(out, outbuflen);
704 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)
705 // first run: get 4^s, 4^s signature
708 // 3. send challenge challenge of SCHNORR_BITS
710 d0_iobuf_t *in = NULL;
711 d0_iobuf_t *out = NULL;
713 // temps: temp0 order, temp0 signature check
716 REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
718 REPLACING(schnorr_G);
724 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
727 USING(rsa_e); USING(rsa_n);
728 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r);
730 in = d0_iobuf_open_read(inbuf, inbuflen);
731 out = d0_iobuf_open_write(outbuf, *outbuflen);
737 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
738 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
739 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
741 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
742 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, zero) > 0);
743 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, ctx->schnorr_G) < 0);
744 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
745 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero) >= 0);
746 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, ctx->rsa_n) < 0);
748 // check signature of key (t = k^d, so, t^challenge = k)
749 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_4_to_s_signature, ctx->rsa_e, ctx->rsa_n));
750 if(d0_bignum_cmp(temp0, ctx->schnorr_4_to_s))
752 // accept the key anyway, but mark as failed signature! will later return 0 in status
753 CHECK(d0_bignum_zero(ctx->schnorr_4_to_s_signature));
757 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
758 ctx->msglen = MSGSIZE;
759 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
762 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
764 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
767 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
768 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
769 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
770 CHECK(d0_iobuf_write_bignum(out, temp0));
773 *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
775 d0_iobuf_close(in, NULL);
776 return d0_iobuf_close(out, outbuflen);
779 d0_iobuf_close(in, NULL);
780 d0_iobuf_close(out, outbuflen);
784 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)
785 // 1. read challenge challenge of SCHNORR_BITS
786 // 2. reply with r + s * challenge mod order
788 d0_iobuf_t *in = NULL;
789 d0_iobuf_t *out = NULL;
791 // temps: 0 order, 1 prod, 2 y, 3 challenge
792 REPLACING(other_4_to_r);
793 USING(schnorr_G); USING(schnorr_s); USING(r);
795 in = d0_iobuf_open_read(inbuf, inbuflen);
796 out = d0_iobuf_open_write(outbuf, *outbuflen);
798 CHECK(d0_iobuf_read_bignum(in, temp3));
799 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
800 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
803 CHECK_ASSIGN(ctx->other_4_to_r, d0_iobuf_read_bignum(in, ctx->other_4_to_r));
804 CHECK(d0_bignum_cmp(ctx->other_4_to_r, zero) > 0);
805 CHECK(d0_bignum_cmp(ctx->other_4_to_r, ctx->schnorr_G) < 0);
807 // send response for schnorr ID scheme
808 // i.challenge. r + ctx->schnorr_s * temp3
809 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
810 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
811 CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
812 CHECK(d0_iobuf_write_bignum(out, temp2));
814 d0_iobuf_close(in, NULL);
815 return d0_iobuf_close(out, outbuflen);
818 d0_iobuf_close(in, NULL);
819 d0_iobuf_close(out, outbuflen);
823 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)
824 // 1. read y = r + s * challenge mod order
825 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
826 // (check using H(g^r) which we know)
828 d0_iobuf_t *in = NULL;
829 static unsigned char convbuf[1024];
830 d0_iobuf_t *conv = NULL;
833 // temps: 0 y 1 order
834 USING(challenge); USING(schnorr_G);
835 REPLACING(other_4_to_r);
837 in = d0_iobuf_open_read(inbuf, inbuflen);
839 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
840 CHECK(d0_iobuf_read_bignum(in, temp0));
841 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
842 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
844 // verify schnorr ID scheme
845 // we need 4^temp0 (g^s)^-challenge
846 CHECK(d0_bignum_neg(temp1, ctx->challenge));
847 CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_4_to_s, temp1, ctx->schnorr_G));
848 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
849 CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mod_mul(ctx->other_4_to_r, temp1, temp2, ctx->schnorr_G));
850 // hash must be equal to msghash
852 // hash it, hash it, everybody hash it
853 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
854 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
855 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
856 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
857 d0_iobuf_close(conv, &sz);
859 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
861 // FAIL (not owned by player)
866 *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
868 if(ctx->msglen <= *msglen)
869 memcpy(msg, ctx->msg, ctx->msglen);
871 memcpy(msg, ctx->msg, *msglen);
872 *msglen = ctx->msglen;
874 d0_iobuf_close(in, NULL);
878 d0_iobuf_close(in, NULL);
882 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
884 d0_iobuf_t *out = NULL;
885 static unsigned char convbuf[1024];
886 d0_iobuf_t *conv = NULL;
889 USING(schnorr_4_to_s);
891 out = d0_iobuf_open_write(outbuf, *outbuflen);
892 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
894 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_4_to_s));
895 CHECK(d0_iobuf_close(conv, &sz));
898 n = (*outbuflen / 4) * 3;
899 if(n > SHA_DIGESTSIZE)
901 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
902 CHECK(d0_iobuf_conv_base64_out(out));
904 return d0_iobuf_close(out, outbuflen);
908 d0_iobuf_close(conv, &sz);
909 d0_iobuf_close(out, outbuflen);
913 BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
915 d0_iobuf_t *out = NULL;
916 static unsigned char convbuf[1024];
917 d0_iobuf_t *conv = NULL;
920 USING(r); USING(other_4_to_r); USING(schnorr_G);
922 out = d0_iobuf_open_write(outbuf, *outbuflen);
923 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
925 // temps: temp0 result
926 CHECK(d0_bignum_mod_pow(temp0, ctx->other_4_to_r, ctx->r, ctx->schnorr_G));
927 CHECK(d0_iobuf_write_bignum(conv, temp0));
928 CHECK(d0_iobuf_close(conv, &sz));
932 if(n > SHA_DIGESTSIZE)
934 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
936 return d0_iobuf_close(out, outbuflen);
940 d0_iobuf_close(conv, &sz);
941 d0_iobuf_close(out, outbuflen);
945 d0_blind_id_t *d0_blind_id_new(void)
947 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
948 memset(b, 0, sizeof(*b));
952 void d0_blind_id_free(d0_blind_id_t *a)
954 d0_blind_id_clear(a);