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 WARN_UNUSED_RESULT BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t *outbuflen)
203 d0_iobuf_t *out = NULL;
204 static unsigned char convbuf[1024];
205 d0_iobuf_t *conv = NULL;
209 while(n > SHA_DIGESTSIZE)
211 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
212 CHECK(d0_iobuf_write_bignum(conv, temp0));
213 CHECK(d0_iobuf_close(conv, &sz));
215 memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
216 outbuf += SHA_DIGESTSIZE;
218 CHECK(d0_bignum_add(temp0, temp0, one));
220 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
221 CHECK(d0_iobuf_write_bignum(conv, temp0));
222 CHECK(d0_iobuf_close(conv, &sz));
224 memcpy(outbuf, sha(convbuf, sz), n);
226 return d0_iobuf_close(out, outbuflen);
230 d0_iobuf_close(conv, &sz);
234 void d0_blind_id_clear(d0_blind_id_t *ctx)
236 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
237 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
238 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
239 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
240 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
241 if(ctx->schnorr_4_to_s) d0_bignum_free(ctx->schnorr_4_to_s);
242 if(ctx->schnorr_4_to_s_signature) d0_bignum_free(ctx->schnorr_4_to_s_signature);
243 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
244 if(ctx->r) d0_bignum_free(ctx->r);
245 if(ctx->challenge) d0_bignum_free(ctx->challenge);
246 if(ctx->other_4_to_r) d0_bignum_free(ctx->other_4_to_r);
247 memset(ctx, 0, sizeof(*ctx));
250 void d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
252 d0_blind_id_clear(ctx);
253 if(src->rsa_n) ctx->rsa_n = d0_bignum_mov(NULL, src->rsa_n);
254 if(src->rsa_e) ctx->rsa_e = d0_bignum_mov(NULL, src->rsa_e);
255 if(src->rsa_d) ctx->rsa_d = d0_bignum_mov(NULL, src->rsa_d);
256 if(src->schnorr_G) ctx->schnorr_G = d0_bignum_mov(NULL, src->schnorr_G);
257 if(src->schnorr_s) ctx->schnorr_s = d0_bignum_mov(NULL, src->schnorr_s);
258 if(src->schnorr_4_to_s) ctx->schnorr_4_to_s = d0_bignum_mov(NULL, ctx->schnorr_G);
259 if(src->schnorr_4_to_s_signature) ctx->schnorr_4_to_s_signature = d0_bignum_mov(NULL, src->schnorr_4_to_s_signature);
260 if(src->rsa_blind_signature_camouflage) ctx->rsa_blind_signature_camouflage = d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage);
261 if(src->r) ctx->r = d0_bignum_mov(NULL, src->r);
262 if(src->challenge) ctx->challenge = d0_bignum_mov(NULL, src->challenge);
263 if(src->other_4_to_r) ctx->other_4_to_r = d0_bignum_mov(NULL, src->other_4_to_r);
264 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
265 ctx->msglen = src->msglen;
266 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
269 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
271 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
273 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
274 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
275 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
276 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
282 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
284 d0_iobuf_t *in = NULL;
286 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
288 in = d0_iobuf_open_read(inbuf, inbuflen);
290 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
291 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
292 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
293 return d0_iobuf_close(in, NULL);
296 d0_iobuf_close(in, NULL);
300 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
302 d0_iobuf_t *in = NULL;
304 REPLACING(rsa_n); REPLACING(rsa_e);
306 in = d0_iobuf_open_read(inbuf, inbuflen);
307 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
308 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
309 return d0_iobuf_close(in, NULL);
312 d0_iobuf_close(in, NULL);
316 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
318 d0_iobuf_t *out = NULL;
320 USING(rsa_n); USING(rsa_e); USING(rsa_d);
322 out = d0_iobuf_open_write(outbuf, *outbuflen);
323 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
324 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
325 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
326 return d0_iobuf_close(out, outbuflen);
329 d0_iobuf_close(out, outbuflen);
333 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
335 d0_iobuf_t *out = NULL;
337 USING(rsa_n); USING(rsa_e);
339 out = d0_iobuf_open_write(outbuf, *outbuflen);
340 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
341 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
342 return d0_iobuf_close(out, outbuflen);
345 if(!d0_iobuf_close(out, outbuflen))
350 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
352 d0_iobuf_t *out = NULL;
353 static unsigned char convbuf[2048];
354 d0_iobuf_t *conv = NULL;
357 USING(rsa_n); USING(rsa_e);
359 out = d0_iobuf_open_write(outbuf, *outbuflen);
360 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
362 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
363 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
364 CHECK(d0_iobuf_close(conv, &sz));
367 n = (*outbuflen / 4) * 3;
368 if(n > SHA_DIGESTSIZE)
370 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
371 CHECK(d0_iobuf_conv_base64_out(out));
373 return d0_iobuf_close(out, outbuflen);
377 d0_iobuf_close(conv, &sz);
378 d0_iobuf_close(out, outbuflen);
382 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
385 REPLACING(schnorr_G);
387 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
388 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
394 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
396 d0_iobuf_t *in = NULL;
398 REPLACING(schnorr_G);
400 in = d0_iobuf_open_read(inbuf, inbuflen);
401 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
402 return d0_iobuf_close(in, NULL);
405 d0_iobuf_close(in, NULL);
409 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
411 d0_iobuf_t *out = NULL;
415 out = d0_iobuf_open_write(outbuf, *outbuflen);
416 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
417 return d0_iobuf_close(out, outbuflen);
420 d0_iobuf_close(out, outbuflen);
424 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
426 // temps: temp0 = order
428 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s);
430 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
431 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
432 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mod_pow(ctx->schnorr_4_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
433 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_zero(ctx->schnorr_4_to_s_signature));
440 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
442 d0_iobuf_t *out = NULL;
444 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
445 USING(rsa_n); USING(rsa_e); USING(schnorr_4_to_s);
446 REPLACING(rsa_blind_signature_camouflage);
448 out = d0_iobuf_open_write(outbuf, *outbuflen);
450 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
451 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
452 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_4_to_s, temp0, ctx->rsa_n));
453 CHECK(d0_iobuf_write_bignum(out, temp1));
454 return d0_iobuf_close(out, outbuflen);
457 d0_iobuf_close(out, outbuflen);
461 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)
463 d0_iobuf_t *in = NULL;
464 d0_iobuf_t *out = NULL;
466 // temps: temp0 input, temp1 temp0^d
467 USING(rsa_d); USING(rsa_n);
469 in = d0_iobuf_open_read(inbuf, inbuflen);
470 out = d0_iobuf_open_write(outbuf, *outbuflen);
472 CHECK(d0_iobuf_read_bignum(in, temp0));
473 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
474 CHECK(d0_iobuf_write_bignum(out, temp1));
476 d0_iobuf_close(in, NULL);
477 return d0_iobuf_close(out, outbuflen);
480 d0_iobuf_close(in, NULL);
481 d0_iobuf_close(out, outbuflen);
485 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
487 d0_iobuf_t *in = NULL;
489 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
490 USING(rsa_blind_signature_camouflage); USING(rsa_n);
491 REPLACING(schnorr_4_to_s_signature);
493 in = d0_iobuf_open_read(inbuf, inbuflen);
495 CHECK(d0_iobuf_read_bignum(in, temp0));
496 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
497 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_4_to_s_signature, temp0, temp1, ctx->rsa_n));
499 return d0_iobuf_close(in, NULL);
502 d0_iobuf_close(in, NULL);
506 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
508 d0_iobuf_t *in = NULL;
510 REPLACING(rsa_blind_signature_camouflage);
512 in = d0_iobuf_open_read(inbuf, inbuflen);
514 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
516 return d0_iobuf_close(in, NULL);
519 d0_iobuf_close(in, NULL);
523 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_request_camouflage(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
525 d0_iobuf_t *out = NULL;
527 USING(rsa_blind_signature_camouflage);
529 out = d0_iobuf_open_write(outbuf, *outbuflen);
531 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
533 return d0_iobuf_close(out, outbuflen);
536 d0_iobuf_close(out, outbuflen);
540 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
542 d0_iobuf_t *in = NULL;
544 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
546 in = d0_iobuf_open_read(inbuf, inbuflen);
548 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
549 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
550 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
552 return d0_iobuf_close(in, NULL);
555 d0_iobuf_close(in, NULL);
559 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
561 d0_iobuf_t *in = NULL;
563 REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
565 in = d0_iobuf_open_read(inbuf, inbuflen);
567 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
568 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
570 return d0_iobuf_close(in, NULL);
573 d0_iobuf_close(in, NULL);
577 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
579 d0_iobuf_t *out = NULL;
581 USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
583 out = d0_iobuf_open_write(outbuf, *outbuflen);
585 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
586 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
587 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
589 return d0_iobuf_close(out, outbuflen);
592 d0_iobuf_close(out, outbuflen);
596 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
598 d0_iobuf_t *out = NULL;
600 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
602 out = d0_iobuf_open_write(outbuf, *outbuflen);
604 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
605 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
607 return d0_iobuf_close(out, outbuflen);
610 d0_iobuf_close(out, outbuflen);
614 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)
616 // first run: send 4^s, 4^s signature
617 // 1. get random r, send HASH(4^r)
619 d0_iobuf_t *out = NULL;
620 static unsigned char convbuf[1024];
621 d0_iobuf_t *conv = NULL;
624 // temps: temp0 order, temp0 4^r
627 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
632 out = d0_iobuf_open_write(outbuf, *outbuflen);
638 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
639 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
640 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
643 // start schnorr ID scheme
644 // generate random number r; x = g^r; send hash of x, remember r, forget x
645 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
646 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
647 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
649 // hash it, hash it, everybody hash it
650 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
651 CHECK(d0_iobuf_write_bignum(conv, temp0));
652 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
653 CHECK(d0_iobuf_write_bignum(conv, temp0));
654 d0_iobuf_close(conv, &sz);
656 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
657 CHECK(d0_iobuf_write_packet(out, msg, msglen));
659 return d0_iobuf_close(out, outbuflen);
662 d0_iobuf_close(out, outbuflen);
666 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)
667 // first run: get 4^s, 4^s signature
670 // 3. send challenge challenge of SCHNORR_BITS
672 d0_iobuf_t *in = NULL;
673 d0_iobuf_t *out = NULL;
675 // temps: temp0 order, temp0 signature check
678 REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
680 REPLACING(schnorr_G);
686 USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
689 USING(rsa_e); USING(rsa_n);
690 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r);
692 in = d0_iobuf_open_read(inbuf, inbuflen);
693 out = d0_iobuf_open_write(outbuf, *outbuflen);
699 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
700 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
701 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
703 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
704 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, zero) > 0);
705 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, ctx->schnorr_G) < 0);
706 CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
707 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero) >= 0);
708 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, ctx->rsa_n) < 0);
710 // check signature of key (t = k^d, so, t^challenge = k)
711 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_4_to_s_signature, ctx->rsa_e, ctx->rsa_n));
712 if(d0_bignum_cmp(temp0, ctx->schnorr_4_to_s))
714 // accept the key anyway, but mark as failed signature! will later return 0 in status
715 CHECK(d0_bignum_zero(ctx->schnorr_4_to_s_signature));
719 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
720 ctx->msglen = MSGSIZE;
721 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
724 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
726 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
729 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
730 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
731 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
732 CHECK(d0_iobuf_write_bignum(out, temp0));
735 *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
737 d0_iobuf_close(in, NULL);
738 return d0_iobuf_close(out, outbuflen);
741 d0_iobuf_close(in, NULL);
742 d0_iobuf_close(out, outbuflen);
746 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)
747 // 1. read challenge challenge of SCHNORR_BITS
748 // 2. reply with r + s * challenge mod order
750 d0_iobuf_t *in = NULL;
751 d0_iobuf_t *out = NULL;
753 // temps: 0 order, 1 prod, 2 y, 3 challenge
754 REPLACING(other_4_to_r);
755 USING(schnorr_G); USING(schnorr_s); USING(r);
757 in = d0_iobuf_open_read(inbuf, inbuflen);
758 out = d0_iobuf_open_write(outbuf, *outbuflen);
760 CHECK(d0_iobuf_read_bignum(in, temp3));
761 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
762 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
765 CHECK_ASSIGN(ctx->other_4_to_r, d0_iobuf_read_bignum(in, ctx->other_4_to_r));
766 CHECK(d0_bignum_cmp(ctx->other_4_to_r, zero) > 0);
767 CHECK(d0_bignum_cmp(ctx->other_4_to_r, ctx->schnorr_G) < 0);
769 // send response for schnorr ID scheme
770 // i.challenge. r + ctx->schnorr_s * temp3
771 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
772 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
773 CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
774 CHECK(d0_iobuf_write_bignum(out, temp2));
776 d0_iobuf_close(in, NULL);
777 return d0_iobuf_close(out, outbuflen);
780 d0_iobuf_close(in, NULL);
781 d0_iobuf_close(out, outbuflen);
785 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)
786 // 1. read y = r + s * challenge mod order
787 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
788 // (check using H(g^r) which we know)
790 d0_iobuf_t *in = NULL;
791 static unsigned char convbuf[1024];
792 d0_iobuf_t *conv = NULL;
795 // temps: 0 y 1 order
796 USING(challenge); USING(schnorr_G);
797 REPLACING(other_4_to_r);
799 in = d0_iobuf_open_read(inbuf, inbuflen);
801 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
802 CHECK(d0_iobuf_read_bignum(in, temp0));
803 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
804 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
806 // verify schnorr ID scheme
807 // we need 4^temp0 (g^s)^-challenge
808 CHECK(d0_bignum_neg(temp1, ctx->challenge));
809 CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_4_to_s, temp1, ctx->schnorr_G));
810 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
811 CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mod_mul(ctx->other_4_to_r, temp1, temp2, ctx->schnorr_G));
812 // hash must be equal to msghash
814 // hash it, hash it, everybody hash it
815 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
816 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
817 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
818 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
819 d0_iobuf_close(conv, &sz);
821 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
823 // FAIL (not owned by player)
828 *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
830 if(ctx->msglen <= *msglen)
831 memcpy(msg, ctx->msg, ctx->msglen);
833 memcpy(msg, ctx->msg, *msglen);
834 *msglen = ctx->msglen;
836 d0_iobuf_close(in, NULL);
840 d0_iobuf_close(in, NULL);
844 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
846 d0_iobuf_t *out = NULL;
847 static unsigned char convbuf[1024];
848 d0_iobuf_t *conv = NULL;
851 USING(schnorr_4_to_s);
853 out = d0_iobuf_open_write(outbuf, *outbuflen);
854 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
856 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_4_to_s));
857 CHECK(d0_iobuf_close(conv, &sz));
860 n = (*outbuflen / 4) * 3;
861 if(n > SHA_DIGESTSIZE)
863 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
864 CHECK(d0_iobuf_conv_base64_out(out));
866 return d0_iobuf_close(out, outbuflen);
870 d0_iobuf_close(conv, &sz);
871 d0_iobuf_close(out, outbuflen);
875 BOOL d0_blind_id_sessionkey_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
877 USING(r); USING(other_4_to_r); USING(schnorr_G);
879 // temps: temp0 result
880 CHECK(d0_bignum_mod_pow(temp0, ctx->other_4_to_r, ctx->r, ctx->schnorr_G));
881 return d0_longhash_destructive(temp0, outbuf, outbuflen);
887 d0_blind_id_t *d0_blind_id_new(void)
889 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
890 memset(b, 0, sizeof(*b));
894 void d0_blind_id_free(d0_blind_id_t *a)
896 d0_blind_id_clear(a);