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"
28 #define SHA_DIGESTSIZE 32
29 const char *sha(const char *in, size_t len)
32 d0_blind_id_util_sha256(h, in, len);
36 // for zero knowledge, we need multiple instances of schnorr ID scheme... should normally be sequential
37 // parallel schnorr ID is not provably zero knowledge :(
38 // (evil verifier can know all questions in advance, so sequential is disadvantage for him)
39 // we'll just live with a 1:1048576 chance of cheating, and support reauthenticating
41 #define SCHNORR_BITS 20
42 // probability of cheat: 2^(-bits+1)
44 #define SCHNORR_HASHSIZE SHA_DIGESTSIZE
45 // cannot be >= SHA_DIGESTSIZE
46 // *8 must be >= SCHNORR_BITS
47 // no need to save bits here
49 #define MSGSIZE 640 // ought to be enough for anyone
53 // signing (Xonotic pub and priv key)
54 d0_bignum_t *rsa_n, *rsa_e, *rsa_d;
56 // public data (Schnorr ID)
57 d0_bignum_t *schnorr_G;
59 // private data (player ID private key)
60 d0_bignum_t *schnorr_s;
62 // public data (player ID public key, this is what the server gets to know)
63 d0_bignum_t *schnorr_g_to_s;
64 d0_bignum_t *schnorr_H_g_to_s_signature; // 0 when signature is invalid
65 // as hash function H, we get the SHA1 and reinterpret as bignum - yes, it always is < 160 bits
68 d0_bignum_t *rsa_blind_signature_camouflage; // random number blind signature
70 d0_bignum_t *r; // random number for schnorr ID
71 d0_bignum_t *t; // for DH key exchange
72 d0_bignum_t *g_to_t; // for DH key exchange
73 d0_bignum_t *other_g_to_t; // for DH key exchange
74 d0_bignum_t *challenge; // challenge
76 char msghash[SCHNORR_HASHSIZE]; // init hash
77 char msg[MSGSIZE]; // message
78 size_t msglen; // message length
81 #define CHECK(x) do { if(!(x)) goto fail; } while(0)
82 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
83 #define MPCHECK(x) do { if(!failed) if(!(x)) failed = 1; } while(0)
84 #define MPCHECK_ASSIGN(var, value) do { if(!failed) { d0_bignum_t *val; val = value; if(val) var = val; else failed = 1; } } while(0)
86 #define USING(x) if(!(ctx->x)) return 0
89 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
91 void d0_blind_id_INITIALIZE(void)
93 d0_bignum_INITIALIZE();
94 CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
95 CHECK_ASSIGN(one, d0_bignum_int(one, 1));
96 CHECK_ASSIGN(four, d0_bignum_int(four, 4));
97 CHECK_ASSIGN(temp0, d0_bignum_int(temp0, 0));
98 CHECK_ASSIGN(temp1, d0_bignum_int(temp1, 0));
99 CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
100 CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
101 CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
106 void d0_blind_id_SHUTDOWN(void)
108 d0_bignum_free(zero);
110 d0_bignum_free(four);
111 d0_bignum_free(temp0);
112 d0_bignum_free(temp1);
113 d0_bignum_free(temp2);
114 d0_bignum_free(temp3);
115 d0_bignum_free(temp4);
116 d0_bignum_SHUTDOWN();
120 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
122 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
123 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
129 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
131 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
132 CHECK(d0_bignum_add(G, G, one));
138 BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
145 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
146 if(d0_bignum_isprime(temp0, 0) == 0)
148 CHECK(d0_dl_get_from_order(G, temp0));
149 if(d0_bignum_isprime(G, 10) == 0)
151 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
160 BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
162 // uses temp0 to temp4
165 int pb = (size + 1)/2;
173 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
174 if(d0_bignum_isprime(temp0, 10) == 0)
176 CHECK(d0_bignum_sub(temp2, temp0, one));
177 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
178 if(!d0_bignum_cmp(temp4, one))
187 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
188 if(!d0_bignum_cmp(temp1, temp0))
194 if(d0_bignum_isprime(temp1, 10) == 0)
196 CHECK(d0_bignum_sub(temp3, temp1, one));
197 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
198 if(!d0_bignum_cmp(temp4, one))
206 CHECK(d0_bignum_mul(n, temp0, temp1));
208 // d = challenge^-1 mod (temp0-1)(temp1-1)
209 CHECK(d0_bignum_mul(temp0, temp2, temp3));
210 CHECK(d0_bignum_mod_inv(d, challenge, temp0));
216 BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
218 // uses temp0 to temp4
221 int pb = (size + 1)/2;
229 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
230 if(d0_bignum_isprime(temp0, 10) == 0)
232 CHECK(d0_bignum_sub(temp2, temp0, one));
233 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
234 if(!d0_bignum_cmp(temp4, one))
243 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
244 if(!d0_bignum_cmp(temp1, temp0))
252 CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
253 if(reject(ctx, pass))
256 if(d0_bignum_isprime(temp1, 10) == 0)
258 CHECK(d0_bignum_sub(temp3, temp1, one));
259 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
260 if(!d0_bignum_cmp(temp4, one))
267 // ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
268 CHECK(d0_bignum_mul(temp0, temp2, temp3));
269 CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
275 WARN_UNUSED_RESULT BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t outbuflen)
277 d0_iobuf_t *out = NULL;
278 static unsigned char convbuf[1024];
282 while(n > SHA_DIGESTSIZE)
284 sz = (d0_bignum_size(clobberme) + 7) / 8;
285 CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
286 memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
287 outbuf += SHA_DIGESTSIZE;
289 CHECK(d0_bignum_add(clobberme, clobberme, one));
291 sz = (d0_bignum_size(clobberme) + 7) / 8;
292 CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
293 memcpy(outbuf, sha(convbuf, sz), n);
300 void d0_blind_id_clear(d0_blind_id_t *ctx)
302 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
303 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
304 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
305 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
306 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
307 if(ctx->schnorr_g_to_s) d0_bignum_free(ctx->schnorr_g_to_s);
308 if(ctx->schnorr_H_g_to_s_signature) d0_bignum_free(ctx->schnorr_H_g_to_s_signature);
309 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
310 if(ctx->r) d0_bignum_free(ctx->r);
311 if(ctx->challenge) d0_bignum_free(ctx->challenge);
312 if(ctx->t) d0_bignum_free(ctx->t);
313 if(ctx->g_to_t) d0_bignum_free(ctx->g_to_t);
314 if(ctx->other_g_to_t) d0_bignum_free(ctx->other_g_to_t);
315 memset(ctx, 0, sizeof(*ctx));
318 WARN_UNUSED_RESULT BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
320 d0_blind_id_clear(ctx);
321 if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
322 if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
323 if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
324 if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
325 if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
326 if(src->schnorr_g_to_s) CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mov(NULL, src->schnorr_g_to_s));
327 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));
328 if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
329 if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
330 if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
331 if(src->t) CHECK_ASSIGN(ctx->t, d0_bignum_mov(NULL, src->t));
332 if(src->g_to_t) CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mov(NULL, src->g_to_t));
333 if(src->other_g_to_t) CHECK_ASSIGN(ctx->other_g_to_t, d0_bignum_mov(NULL, src->other_g_to_t));
334 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
335 ctx->msglen = src->msglen;
336 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
339 d0_blind_id_clear(ctx);
343 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key_fastreject(d0_blind_id_t *ctx, int k, d0_fastreject_function reject, void *pass)
345 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
347 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
348 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
349 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
351 CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
353 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
359 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
361 return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
364 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
366 d0_iobuf_t *in = NULL;
368 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
370 in = d0_iobuf_open_read(inbuf, inbuflen);
372 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
373 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
374 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
375 return d0_iobuf_close(in, NULL);
378 d0_iobuf_close(in, NULL);
382 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
384 d0_iobuf_t *in = NULL;
386 REPLACING(rsa_n); REPLACING(rsa_e);
388 in = d0_iobuf_open_read(inbuf, inbuflen);
389 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
390 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
391 return d0_iobuf_close(in, NULL);
394 d0_iobuf_close(in, NULL);
398 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
400 d0_iobuf_t *out = NULL;
402 USING(rsa_n); USING(rsa_e); USING(rsa_d);
404 out = d0_iobuf_open_write(outbuf, *outbuflen);
405 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
406 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
407 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
408 return d0_iobuf_close(out, outbuflen);
411 d0_iobuf_close(out, outbuflen);
415 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
417 d0_iobuf_t *out = NULL;
419 USING(rsa_n); USING(rsa_e);
421 out = d0_iobuf_open_write(outbuf, *outbuflen);
422 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
423 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
424 return d0_iobuf_close(out, outbuflen);
427 if(!d0_iobuf_close(out, outbuflen))
432 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
434 d0_iobuf_t *out = NULL;
435 static unsigned char convbuf[2048];
436 d0_iobuf_t *conv = NULL;
439 USING(rsa_n); USING(rsa_e);
441 out = d0_iobuf_open_write(outbuf, *outbuflen);
442 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
444 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
445 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
446 CHECK(d0_iobuf_close(conv, &sz));
449 n = (*outbuflen / 4) * 3;
450 if(n > SHA_DIGESTSIZE)
452 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
453 CHECK(d0_iobuf_conv_base64_out(out));
455 return d0_iobuf_close(out, outbuflen);
459 d0_iobuf_close(conv, &sz);
460 d0_iobuf_close(out, outbuflen);
464 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
467 REPLACING(schnorr_G);
469 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
470 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
476 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
478 d0_iobuf_t *in = NULL;
480 REPLACING(schnorr_G);
482 in = d0_iobuf_open_read(inbuf, inbuflen);
483 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
484 return d0_iobuf_close(in, NULL);
487 d0_iobuf_close(in, NULL);
491 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
493 d0_iobuf_t *out = NULL;
497 out = d0_iobuf_open_write(outbuf, *outbuflen);
498 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
499 return d0_iobuf_close(out, outbuflen);
502 d0_iobuf_close(out, outbuflen);
506 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
508 // temps: temp0 = order
510 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s);
512 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
513 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
514 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mod_pow(ctx->schnorr_g_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
515 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
522 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
524 d0_iobuf_t *out = NULL;
525 static unsigned char convbuf[2048], shabuf[2048];
528 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
529 USING(rsa_n); USING(rsa_e); USING(schnorr_g_to_s);
530 REPLACING(rsa_blind_signature_camouflage);
532 out = d0_iobuf_open_write(outbuf, *outbuflen);
534 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
535 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
537 // we will actually sign HA(4^s) to prevent a malleability attack!
538 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
539 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
540 if(sz > sizeof(shabuf))
542 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
543 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
546 CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
547 CHECK(d0_iobuf_write_bignum(out, temp1));
548 return d0_iobuf_close(out, outbuflen);
551 d0_iobuf_close(out, outbuflen);
555 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)
557 d0_iobuf_t *in = NULL;
558 d0_iobuf_t *out = NULL;
560 // temps: temp0 input, temp1 temp0^d
561 USING(rsa_d); USING(rsa_n);
563 in = d0_iobuf_open_read(inbuf, inbuflen);
564 out = d0_iobuf_open_write(outbuf, *outbuflen);
566 CHECK(d0_iobuf_read_bignum(in, temp0));
567 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
568 CHECK(d0_iobuf_write_bignum(out, temp1));
570 d0_iobuf_close(in, NULL);
571 return d0_iobuf_close(out, outbuflen);
574 d0_iobuf_close(in, NULL);
575 d0_iobuf_close(out, outbuflen);
579 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
581 d0_iobuf_t *in = NULL;
583 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
584 USING(rsa_blind_signature_camouflage); USING(rsa_n);
585 REPLACING(schnorr_H_g_to_s_signature);
587 in = d0_iobuf_open_read(inbuf, inbuflen);
589 CHECK(d0_iobuf_read_bignum(in, temp0));
590 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
591 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));
593 return d0_iobuf_close(in, NULL);
596 d0_iobuf_close(in, NULL);
600 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
602 d0_iobuf_t *in = NULL;
604 REPLACING(rsa_blind_signature_camouflage);
606 in = d0_iobuf_open_read(inbuf, inbuflen);
608 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
610 return d0_iobuf_close(in, NULL);
613 d0_iobuf_close(in, NULL);
617 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_request_camouflage(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
619 d0_iobuf_t *out = NULL;
621 USING(rsa_blind_signature_camouflage);
623 out = d0_iobuf_open_write(outbuf, *outbuflen);
625 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
627 return d0_iobuf_close(out, outbuflen);
630 d0_iobuf_close(out, outbuflen);
634 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
636 d0_iobuf_t *in = NULL;
638 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
640 in = d0_iobuf_open_read(inbuf, inbuflen);
642 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
643 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
644 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
646 return d0_iobuf_close(in, NULL);
649 d0_iobuf_close(in, NULL);
653 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
655 d0_iobuf_t *in = NULL;
657 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
659 in = d0_iobuf_open_read(inbuf, inbuflen);
661 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
662 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
664 return d0_iobuf_close(in, NULL);
667 d0_iobuf_close(in, NULL);
671 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
673 d0_iobuf_t *out = NULL;
675 USING(schnorr_s); USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
677 out = d0_iobuf_open_write(outbuf, *outbuflen);
679 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
680 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
681 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
683 return d0_iobuf_close(out, outbuflen);
686 d0_iobuf_close(out, outbuflen);
690 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
692 d0_iobuf_t *out = NULL;
694 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
696 out = d0_iobuf_open_write(outbuf, *outbuflen);
698 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
699 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
701 return d0_iobuf_close(out, outbuflen);
704 d0_iobuf_close(out, outbuflen);
708 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)
710 // first run: send 4^s, 4^s signature
711 // 1. get random r, send HASH(4^r)
713 d0_iobuf_t *out = NULL;
714 static unsigned char convbuf[1024];
715 d0_iobuf_t *conv = NULL;
719 // temps: temp0 order, temp0 4^r
722 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
725 REPLACING(r); REPLACING(t); REPLACING(g_to_t);
727 out = d0_iobuf_open_write(outbuf, *outbuflen);
733 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
734 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
735 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
738 // start schnorr ID scheme
739 // generate random number r; x = g^r; send hash of x, remember r, forget x
740 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
741 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
742 //CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
744 // initialize Signed Diffie Hellmann
745 // we already have the group order in temp1
746 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
747 // can we SOMEHOW do this with just one mod_pow?
749 #pragma omp parallel default(shared) reduction(||:failed)
754 MPCHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
758 MPCHECK_ASSIGN(ctx->g_to_t, d0_bignum_mod_pow(ctx->g_to_t, four, ctx->t, ctx->schnorr_G));
763 // hash it, hash it, everybody hash it
764 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
765 CHECK(d0_iobuf_write_bignum(conv, temp0));
766 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
767 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
768 CHECK(d0_iobuf_write_bignum(conv, temp0));
769 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
770 d0_iobuf_close(conv, &sz);
772 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
773 CHECK(d0_iobuf_write_packet(out, msg, msglen));
775 return d0_iobuf_close(out, outbuflen);
778 d0_iobuf_close(out, outbuflen);
782 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)
783 // first run: get 4^s, 4^s signature
786 // 3. send challenge challenge of SCHNORR_BITS
788 d0_iobuf_t *in = NULL;
789 d0_iobuf_t *out = NULL;
790 static unsigned char shabuf[2048];
793 // temps: temp0 order, temp0 signature check
796 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
798 REPLACING(schnorr_G);
804 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
807 USING(rsa_e); USING(rsa_n);
808 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r); REPLACING(t);
810 in = d0_iobuf_open_read(inbuf, inbuflen);
811 out = d0_iobuf_open_write(outbuf, *outbuflen);
817 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
818 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
819 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
821 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
822 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
823 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
824 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
825 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
826 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
828 // check signature of key (t = k^d, so, t^challenge = k)
829 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
831 // we will actually sign SHA(4^s) to prevent a malleability attack!
832 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
833 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
834 if(sz > sizeof(shabuf))
836 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
837 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
839 // + 7 / 8 is too large, so let's mod it
840 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
843 if(d0_bignum_cmp(temp0, temp1))
845 // accept the key anyway, but mark as failed signature! will later return 0 in status
846 CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
850 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
851 ctx->msglen = MSGSIZE;
852 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
855 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
856 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
858 // Diffie Hellmann send
859 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
860 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
861 CHECK(d0_bignum_mod_pow(temp0, four, ctx->t, ctx->schnorr_G));
862 CHECK(d0_iobuf_write_bignum(out, temp0));
865 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
867 d0_iobuf_close(in, NULL);
868 return d0_iobuf_close(out, outbuflen);
871 d0_iobuf_close(in, NULL);
872 d0_iobuf_close(out, outbuflen);
876 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)
877 // 1. read challenge challenge of SCHNORR_BITS
878 // 2. reply with r + s * challenge mod order
880 d0_iobuf_t *in = NULL;
881 d0_iobuf_t *out = NULL;
883 // temps: 0 order, 1 prod, 2 y, 3 challenge
884 REPLACING(other_g_to_t); REPLACING(t);
885 USING(schnorr_G); USING(schnorr_s); USING(r); USING(g_to_t);
887 in = d0_iobuf_open_read(inbuf, inbuflen);
888 out = d0_iobuf_open_write(outbuf, *outbuflen);
890 CHECK(d0_iobuf_read_bignum(in, temp3));
891 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
892 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
894 // send response for schnorr ID scheme
895 // i.challenge. r + ctx->schnorr_s * temp3
896 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
897 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
898 CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
899 CHECK(d0_iobuf_write_bignum(out, temp2));
901 // Diffie Hellmann recv
902 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
903 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
904 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
905 // Diffie Hellmann send
906 CHECK(d0_iobuf_write_bignum(out, ctx->g_to_t));
908 d0_iobuf_close(in, NULL);
909 return d0_iobuf_close(out, outbuflen);
912 d0_iobuf_close(in, NULL);
913 d0_iobuf_close(out, outbuflen);
917 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)
918 // 1. read y = r + s * challenge mod order
919 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
920 // (check using H(g^r) which we know)
922 d0_iobuf_t *in = NULL;
923 static unsigned char convbuf[1024];
924 d0_iobuf_t *conv = NULL;
927 // temps: 0 y 1 order
928 USING(challenge); USING(schnorr_G);
929 REPLACING(other_g_to_t);
931 in = d0_iobuf_open_read(inbuf, inbuflen);
933 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
934 CHECK(d0_iobuf_read_bignum(in, temp0));
935 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
936 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
938 // verify schnorr ID scheme
939 // we need 4^r = 4^temp0 (g^s)^-challenge
940 CHECK(d0_bignum_mod_inv(temp1, ctx->schnorr_g_to_s, ctx->schnorr_G));
941 CHECK(d0_bignum_mod_pow(temp2, temp1, ctx->challenge, ctx->schnorr_G));
942 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
943 CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G));
945 // Diffie Hellmann recv
946 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
947 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
948 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
950 // hash it, hash it, everybody hash it
951 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
952 CHECK(d0_iobuf_write_bignum(conv, temp3));
953 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
954 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
955 CHECK(d0_iobuf_write_bignum(conv, temp3));
956 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
957 d0_iobuf_close(conv, &sz);
959 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
961 // FAIL (not owned by player)
966 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
968 if(ctx->msglen <= *msglen)
969 memcpy(msg, ctx->msg, ctx->msglen);
971 memcpy(msg, ctx->msg, *msglen);
972 *msglen = ctx->msglen;
974 d0_iobuf_close(in, NULL);
978 d0_iobuf_close(in, NULL);
982 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
984 d0_iobuf_t *out = NULL;
985 static unsigned char convbuf[1024];
986 d0_iobuf_t *conv = NULL;
989 USING(schnorr_g_to_s);
991 out = d0_iobuf_open_write(outbuf, *outbuflen);
992 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
994 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_g_to_s));
995 CHECK(d0_iobuf_close(conv, &sz));
998 n = (*outbuflen / 4) * 3;
999 if(n > SHA_DIGESTSIZE)
1001 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
1002 CHECK(d0_iobuf_conv_base64_out(out));
1004 return d0_iobuf_close(out, outbuflen);
1008 d0_iobuf_close(conv, &sz);
1009 d0_iobuf_close(out, outbuflen);
1013 BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
1015 USING(t); USING(other_g_to_t); USING(schnorr_G);
1017 // temps: temp0 result
1018 CHECK(d0_bignum_mod_pow(temp0, ctx->other_g_to_t, ctx->t, ctx->schnorr_G));
1019 return d0_longhash_destructive(temp0, outbuf, *outbuflen);
1025 d0_blind_id_t *d0_blind_id_new(void)
1027 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
1028 memset(b, 0, sizeof(*b));
1032 void d0_blind_id_free(d0_blind_id_t *a)
1034 d0_blind_id_clear(a);
1038 void d0_blind_id_util_sha256(char *out, const char *in, size_t n)
1041 SHA256_Init(&context);
1042 SHA256_Update(&context, (const unsigned char *) in, n);
1043 return SHA256_Final((unsigned char *) out, &context);