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 WARN_UNUSED_RESULT BOOL d0_blind_id_INITIALIZE(void)
93 CHECK(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));
107 void d0_blind_id_SHUTDOWN(void)
109 d0_bignum_free(zero);
111 d0_bignum_free(four);
112 d0_bignum_free(temp0);
113 d0_bignum_free(temp1);
114 d0_bignum_free(temp2);
115 d0_bignum_free(temp3);
116 d0_bignum_free(temp4);
117 d0_bignum_SHUTDOWN();
121 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
123 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
124 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
130 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
132 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
133 CHECK(d0_bignum_add(G, G, one));
139 BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
146 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
147 if(d0_bignum_isprime(temp0, 0) == 0)
149 CHECK(d0_dl_get_from_order(G, temp0));
150 if(d0_bignum_isprime(G, 10) == 0)
152 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
161 BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
163 // uses temp0 to temp4
166 int pb = (size + 1)/2;
174 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
175 if(d0_bignum_isprime(temp0, 10) == 0)
177 CHECK(d0_bignum_sub(temp2, temp0, one));
178 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
179 if(!d0_bignum_cmp(temp4, one))
188 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
189 if(!d0_bignum_cmp(temp1, temp0))
195 if(d0_bignum_isprime(temp1, 10) == 0)
197 CHECK(d0_bignum_sub(temp3, temp1, one));
198 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
199 if(!d0_bignum_cmp(temp4, one))
207 CHECK(d0_bignum_mul(n, temp0, temp1));
209 // d = challenge^-1 mod (temp0-1)(temp1-1)
210 CHECK(d0_bignum_mul(temp0, temp2, temp3));
211 CHECK(d0_bignum_mod_inv(d, challenge, temp0));
217 BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
219 // uses temp0 to temp4
222 int pb = (size + 1)/2;
230 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
231 if(d0_bignum_isprime(temp0, 10) == 0)
233 CHECK(d0_bignum_sub(temp2, temp0, one));
234 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
235 if(!d0_bignum_cmp(temp4, one))
244 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
245 if(!d0_bignum_cmp(temp1, temp0))
253 CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
254 if(reject(ctx, pass))
257 if(d0_bignum_isprime(temp1, 10) == 0)
259 CHECK(d0_bignum_sub(temp3, temp1, one));
260 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
261 if(!d0_bignum_cmp(temp4, one))
268 // ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
269 CHECK(d0_bignum_mul(temp0, temp2, temp3));
270 CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
276 WARN_UNUSED_RESULT BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t outbuflen)
278 d0_iobuf_t *out = NULL;
279 static unsigned char convbuf[1024];
283 while(n > SHA_DIGESTSIZE)
285 sz = (d0_bignum_size(clobberme) + 7) / 8;
286 CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
287 memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
288 outbuf += SHA_DIGESTSIZE;
290 CHECK(d0_bignum_add(clobberme, clobberme, one));
292 sz = (d0_bignum_size(clobberme) + 7) / 8;
293 CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
294 memcpy(outbuf, sha(convbuf, sz), n);
301 void d0_blind_id_clear(d0_blind_id_t *ctx)
303 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
304 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
305 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
306 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
307 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
308 if(ctx->schnorr_g_to_s) d0_bignum_free(ctx->schnorr_g_to_s);
309 if(ctx->schnorr_H_g_to_s_signature) d0_bignum_free(ctx->schnorr_H_g_to_s_signature);
310 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
311 if(ctx->r) d0_bignum_free(ctx->r);
312 if(ctx->challenge) d0_bignum_free(ctx->challenge);
313 if(ctx->t) d0_bignum_free(ctx->t);
314 if(ctx->g_to_t) d0_bignum_free(ctx->g_to_t);
315 if(ctx->other_g_to_t) d0_bignum_free(ctx->other_g_to_t);
316 memset(ctx, 0, sizeof(*ctx));
319 WARN_UNUSED_RESULT BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
321 d0_blind_id_clear(ctx);
322 if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
323 if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
324 if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
325 if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
326 if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
327 if(src->schnorr_g_to_s) CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mov(NULL, src->schnorr_g_to_s));
328 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));
329 if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
330 if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
331 if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
332 if(src->t) CHECK_ASSIGN(ctx->t, d0_bignum_mov(NULL, src->t));
333 if(src->g_to_t) CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mov(NULL, src->g_to_t));
334 if(src->other_g_to_t) CHECK_ASSIGN(ctx->other_g_to_t, d0_bignum_mov(NULL, src->other_g_to_t));
335 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
336 ctx->msglen = src->msglen;
337 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
340 d0_blind_id_clear(ctx);
344 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key_fastreject(d0_blind_id_t *ctx, int k, d0_fastreject_function reject, void *pass)
346 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
348 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
349 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
350 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
352 CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
354 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
360 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
362 return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
365 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
367 d0_iobuf_t *in = NULL;
369 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
371 in = d0_iobuf_open_read(inbuf, inbuflen);
373 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
374 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
375 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
376 return d0_iobuf_close(in, NULL);
379 d0_iobuf_close(in, NULL);
383 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
385 d0_iobuf_t *in = NULL;
387 REPLACING(rsa_n); REPLACING(rsa_e);
389 in = d0_iobuf_open_read(inbuf, inbuflen);
390 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
391 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
392 return d0_iobuf_close(in, NULL);
395 d0_iobuf_close(in, NULL);
399 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
401 d0_iobuf_t *out = NULL;
403 USING(rsa_n); USING(rsa_e); USING(rsa_d);
405 out = d0_iobuf_open_write(outbuf, *outbuflen);
406 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
407 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
408 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
409 return d0_iobuf_close(out, outbuflen);
412 d0_iobuf_close(out, outbuflen);
416 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
418 d0_iobuf_t *out = NULL;
420 USING(rsa_n); USING(rsa_e);
422 out = d0_iobuf_open_write(outbuf, *outbuflen);
423 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
424 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
425 return d0_iobuf_close(out, outbuflen);
428 if(!d0_iobuf_close(out, outbuflen))
433 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
435 d0_iobuf_t *out = NULL;
436 static unsigned char convbuf[2048];
437 d0_iobuf_t *conv = NULL;
440 USING(rsa_n); USING(rsa_e);
442 out = d0_iobuf_open_write(outbuf, *outbuflen);
443 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
445 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
446 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
447 CHECK(d0_iobuf_close(conv, &sz));
450 n = (*outbuflen / 4) * 3;
451 if(n > SHA_DIGESTSIZE)
453 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
454 CHECK(d0_iobuf_conv_base64_out(out));
456 return d0_iobuf_close(out, outbuflen);
460 d0_iobuf_close(conv, &sz);
461 d0_iobuf_close(out, outbuflen);
465 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
468 REPLACING(schnorr_G);
470 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
471 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
477 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
479 d0_iobuf_t *in = NULL;
481 REPLACING(schnorr_G);
483 in = d0_iobuf_open_read(inbuf, inbuflen);
484 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
485 return d0_iobuf_close(in, NULL);
488 d0_iobuf_close(in, NULL);
492 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
494 d0_iobuf_t *out = NULL;
498 out = d0_iobuf_open_write(outbuf, *outbuflen);
499 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
500 return d0_iobuf_close(out, outbuflen);
503 d0_iobuf_close(out, outbuflen);
507 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
509 // temps: temp0 = order
511 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s);
513 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
514 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
515 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mod_pow(ctx->schnorr_g_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
516 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
523 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
525 d0_iobuf_t *out = NULL;
526 static unsigned char convbuf[2048], shabuf[2048];
529 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
530 USING(rsa_n); USING(rsa_e); USING(schnorr_g_to_s);
531 REPLACING(rsa_blind_signature_camouflage);
533 out = d0_iobuf_open_write(outbuf, *outbuflen);
535 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
536 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
538 // we will actually sign HA(4^s) to prevent a malleability attack!
539 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
540 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
541 if(sz > sizeof(shabuf))
543 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
544 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
547 CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
548 CHECK(d0_iobuf_write_bignum(out, temp1));
549 return d0_iobuf_close(out, outbuflen);
552 d0_iobuf_close(out, outbuflen);
556 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)
558 d0_iobuf_t *in = NULL;
559 d0_iobuf_t *out = NULL;
561 // temps: temp0 input, temp1 temp0^d
562 USING(rsa_d); USING(rsa_n);
564 in = d0_iobuf_open_read(inbuf, inbuflen);
565 out = d0_iobuf_open_write(outbuf, *outbuflen);
567 CHECK(d0_iobuf_read_bignum(in, temp0));
568 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
569 CHECK(d0_iobuf_write_bignum(out, temp1));
571 d0_iobuf_close(in, NULL);
572 return d0_iobuf_close(out, outbuflen);
575 d0_iobuf_close(in, NULL);
576 d0_iobuf_close(out, outbuflen);
580 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
582 d0_iobuf_t *in = NULL;
584 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
585 USING(rsa_blind_signature_camouflage); USING(rsa_n);
586 REPLACING(schnorr_H_g_to_s_signature);
588 in = d0_iobuf_open_read(inbuf, inbuflen);
590 CHECK(d0_iobuf_read_bignum(in, temp0));
591 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
592 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));
594 return d0_iobuf_close(in, NULL);
597 d0_iobuf_close(in, NULL);
601 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
603 d0_iobuf_t *in = NULL;
605 REPLACING(rsa_blind_signature_camouflage);
607 in = d0_iobuf_open_read(inbuf, inbuflen);
609 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
611 return d0_iobuf_close(in, NULL);
614 d0_iobuf_close(in, NULL);
618 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_request_camouflage(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
620 d0_iobuf_t *out = NULL;
622 USING(rsa_blind_signature_camouflage);
624 out = d0_iobuf_open_write(outbuf, *outbuflen);
626 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
628 return d0_iobuf_close(out, outbuflen);
631 d0_iobuf_close(out, outbuflen);
635 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
637 d0_iobuf_t *in = NULL;
639 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
641 in = d0_iobuf_open_read(inbuf, inbuflen);
643 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
644 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
645 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
647 return d0_iobuf_close(in, NULL);
650 d0_iobuf_close(in, NULL);
654 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
656 d0_iobuf_t *in = NULL;
658 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
660 in = d0_iobuf_open_read(inbuf, inbuflen);
662 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
663 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
665 return d0_iobuf_close(in, NULL);
668 d0_iobuf_close(in, NULL);
672 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
674 d0_iobuf_t *out = NULL;
676 USING(schnorr_s); USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
678 out = d0_iobuf_open_write(outbuf, *outbuflen);
680 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
681 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
682 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
684 return d0_iobuf_close(out, outbuflen);
687 d0_iobuf_close(out, outbuflen);
691 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
693 d0_iobuf_t *out = NULL;
695 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
697 out = d0_iobuf_open_write(outbuf, *outbuflen);
699 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
700 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
702 return d0_iobuf_close(out, outbuflen);
705 d0_iobuf_close(out, outbuflen);
709 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)
711 // first run: send 4^s, 4^s signature
712 // 1. get random r, send HASH(4^r)
714 d0_iobuf_t *out = NULL;
715 static unsigned char convbuf[1024];
716 d0_iobuf_t *conv = NULL;
720 // temps: temp0 order, temp0 4^r
723 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
726 REPLACING(r); REPLACING(t); REPLACING(g_to_t);
728 out = d0_iobuf_open_write(outbuf, *outbuflen);
734 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
735 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
736 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
739 // start schnorr ID scheme
740 // generate random number r; x = g^r; send hash of x, remember r, forget x
741 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
742 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
743 //CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
745 // initialize Signed Diffie Hellmann
746 // we already have the group order in temp1
747 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
748 // can we SOMEHOW do this with just one mod_pow?
750 #pragma omp parallel default(shared) reduction(||:failed)
755 MPCHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
759 MPCHECK_ASSIGN(ctx->g_to_t, d0_bignum_mod_pow(ctx->g_to_t, four, ctx->t, ctx->schnorr_G));
764 // hash it, hash it, everybody hash it
765 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
766 CHECK(d0_iobuf_write_bignum(conv, temp0));
767 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
768 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
769 CHECK(d0_iobuf_write_bignum(conv, temp0));
770 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
771 d0_iobuf_close(conv, &sz);
773 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
774 CHECK(d0_iobuf_write_packet(out, msg, msglen));
776 return d0_iobuf_close(out, outbuflen);
779 d0_iobuf_close(out, outbuflen);
783 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)
784 // first run: get 4^s, 4^s signature
787 // 3. send challenge challenge of SCHNORR_BITS
789 d0_iobuf_t *in = NULL;
790 d0_iobuf_t *out = NULL;
791 static unsigned char shabuf[2048];
794 // temps: temp0 order, temp0 signature check
797 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
799 REPLACING(schnorr_G);
805 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
808 USING(rsa_e); USING(rsa_n);
809 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r); REPLACING(t);
811 in = d0_iobuf_open_read(inbuf, inbuflen);
812 out = d0_iobuf_open_write(outbuf, *outbuflen);
818 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
819 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
820 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
822 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
823 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
824 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
825 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
826 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
827 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
829 // check signature of key (t = k^d, so, t^challenge = k)
830 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
832 // we will actually sign SHA(4^s) to prevent a malleability attack!
833 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
834 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
835 if(sz > sizeof(shabuf))
837 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
838 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
840 // + 7 / 8 is too large, so let's mod it
841 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
844 if(d0_bignum_cmp(temp0, temp1))
846 // accept the key anyway, but mark as failed signature! will later return 0 in status
847 CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
851 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
852 ctx->msglen = MSGSIZE;
853 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
856 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
857 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
859 // Diffie Hellmann send
860 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
861 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
862 CHECK(d0_bignum_mod_pow(temp0, four, ctx->t, ctx->schnorr_G));
863 CHECK(d0_iobuf_write_bignum(out, temp0));
866 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
868 d0_iobuf_close(in, NULL);
869 return d0_iobuf_close(out, outbuflen);
872 d0_iobuf_close(in, NULL);
873 d0_iobuf_close(out, outbuflen);
877 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)
878 // 1. read challenge challenge of SCHNORR_BITS
879 // 2. reply with r + s * challenge mod order
881 d0_iobuf_t *in = NULL;
882 d0_iobuf_t *out = NULL;
884 // temps: 0 order, 1 prod, 2 y, 3 challenge
885 REPLACING(other_g_to_t); REPLACING(t);
886 USING(schnorr_G); USING(schnorr_s); USING(r); USING(g_to_t);
888 in = d0_iobuf_open_read(inbuf, inbuflen);
889 out = d0_iobuf_open_write(outbuf, *outbuflen);
891 CHECK(d0_iobuf_read_bignum(in, temp3));
892 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
893 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
895 // send response for schnorr ID scheme
896 // i.challenge. r + ctx->schnorr_s * temp3
897 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
898 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
899 CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
900 CHECK(d0_iobuf_write_bignum(out, temp2));
902 // Diffie Hellmann recv
903 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
904 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
905 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
906 // Diffie Hellmann send
907 CHECK(d0_iobuf_write_bignum(out, ctx->g_to_t));
909 d0_iobuf_close(in, NULL);
910 return d0_iobuf_close(out, outbuflen);
913 d0_iobuf_close(in, NULL);
914 d0_iobuf_close(out, outbuflen);
918 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)
919 // 1. read y = r + s * challenge mod order
920 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
921 // (check using H(g^r) which we know)
923 d0_iobuf_t *in = NULL;
924 static unsigned char convbuf[1024];
925 d0_iobuf_t *conv = NULL;
928 // temps: 0 y 1 order
929 USING(challenge); USING(schnorr_G);
930 REPLACING(other_g_to_t);
932 in = d0_iobuf_open_read(inbuf, inbuflen);
934 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
935 CHECK(d0_iobuf_read_bignum(in, temp0));
936 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
937 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
939 // verify schnorr ID scheme
940 // we need 4^r = 4^temp0 (g^s)^-challenge
941 CHECK(d0_bignum_mod_inv(temp1, ctx->schnorr_g_to_s, ctx->schnorr_G));
942 CHECK(d0_bignum_mod_pow(temp2, temp1, ctx->challenge, ctx->schnorr_G));
943 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
944 CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G));
946 // Diffie Hellmann recv
947 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
948 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
949 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
951 // hash it, hash it, everybody hash it
952 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
953 CHECK(d0_iobuf_write_bignum(conv, temp3));
954 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
955 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
956 CHECK(d0_iobuf_write_bignum(conv, temp3));
957 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
958 d0_iobuf_close(conv, &sz);
960 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
962 // FAIL (not owned by player)
967 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
969 if(ctx->msglen <= *msglen)
970 memcpy(msg, ctx->msg, ctx->msglen);
972 memcpy(msg, ctx->msg, *msglen);
973 *msglen = ctx->msglen;
975 d0_iobuf_close(in, NULL);
979 d0_iobuf_close(in, NULL);
983 WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_generate_missing_signature(d0_blind_id_t *ctx)
986 static unsigned char shabuf[2048];
988 REPLACING(schnorr_H_g_to_s_signature);
989 USING(schnorr_g_to_s); USING(rsa_d); USING(rsa_n);
991 // we will actually sign SHA(4^s) to prevent a malleability attack!
992 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
993 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
994 if(sz > sizeof(shabuf))
996 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
997 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
999 // + 7 / 8 is too large, so let's mod it
1000 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
1001 CHECK(d0_bignum_mod_pow(ctx->schnorr_H_g_to_s_signature, temp1, ctx->rsa_d, ctx->rsa_n));
1008 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
1010 d0_iobuf_t *out = NULL;
1011 static unsigned char convbuf[1024];
1012 d0_iobuf_t *conv = NULL;
1015 USING(schnorr_g_to_s);
1017 out = d0_iobuf_open_write(outbuf, *outbuflen);
1018 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
1020 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_g_to_s));
1021 CHECK(d0_iobuf_close(conv, &sz));
1024 n = (*outbuflen / 4) * 3;
1025 if(n > SHA_DIGESTSIZE)
1027 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
1028 CHECK(d0_iobuf_conv_base64_out(out));
1030 return d0_iobuf_close(out, outbuflen);
1034 d0_iobuf_close(conv, &sz);
1035 d0_iobuf_close(out, outbuflen);
1039 BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
1041 USING(t); USING(other_g_to_t); USING(schnorr_G);
1043 // temps: temp0 result
1044 CHECK(d0_bignum_mod_pow(temp0, ctx->other_g_to_t, ctx->t, ctx->schnorr_G));
1045 return d0_longhash_destructive(temp0, outbuf, *outbuflen);
1051 d0_blind_id_t *d0_blind_id_new(void)
1053 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
1054 memset(b, 0, sizeof(*b));
1058 void d0_blind_id_free(d0_blind_id_t *a)
1060 d0_blind_id_clear(a);
1064 void d0_blind_id_util_sha256(char *out, const char *in, size_t n)
1067 SHA256_Init(&context);
1068 SHA256_Update(&context, (const unsigned char *) in, n);
1069 return SHA256_Final((unsigned char *) out, &context);