3 * AUTHOR: Rudolf Polzer - divVerent@xonotic.org
5 * Copyright (c) 2010, Rudolf Polzer
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the copyright holder nor the names of contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTOR(S) ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTOR(S) BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 #include "d0_blind_id.h"
40 #include "d0_bignum.h"
43 // old "positive" protocol, uses one extra mod_inv in verify stages
44 // #define D0_BLIND_ID_POSITIVE_PROTOCOL
47 #define SHA_DIGESTSIZE 32
48 const char *sha(const unsigned char *in, size_t len)
51 d0_blind_id_util_sha256(h, (const char *) in, len);
55 // for zero knowledge, we need multiple instances of schnorr ID scheme... should normally be sequential
56 // parallel schnorr ID is not provably zero knowledge :(
57 // (evil verifier can know all questions in advance, so sequential is disadvantage for him)
58 // we'll just live with a 1:1048576 chance of cheating, and support reauthenticating
60 #define SCHNORR_BITS 20
61 // probability of cheat: 2^(-bits+1)
63 #define SCHNORR_HASHSIZE SHA_DIGESTSIZE
64 // cannot be >= SHA_DIGESTSIZE
65 // *8 must be >= SCHNORR_BITS
66 // no need to save bits here
68 #define MSGSIZE 640 // ought to be enough for anyone
72 // signing (Xonotic pub and priv key)
73 d0_bignum_t *rsa_n, *rsa_e, *rsa_d;
75 // public data (Schnorr ID)
76 d0_bignum_t *schnorr_G;
78 // private data (player ID private key)
79 d0_bignum_t *schnorr_s;
81 // public data (player ID public key, this is what the server gets to know)
82 d0_bignum_t *schnorr_g_to_s;
83 d0_bignum_t *schnorr_H_g_to_s_signature; // 0 when signature is invalid
84 // as hash function H, we get the SHA1 and reinterpret as bignum - yes, it always is < 160 bits
87 d0_bignum_t *rsa_blind_signature_camouflage; // random number blind signature
89 d0_bignum_t *r; // random number for schnorr ID
90 d0_bignum_t *t; // for DH key exchange
91 d0_bignum_t *g_to_t; // for DH key exchange
92 d0_bignum_t *other_g_to_t; // for DH key exchange
93 d0_bignum_t *challenge; // challenge
95 char msghash[SCHNORR_HASHSIZE]; // init hash
96 char msg[MSGSIZE]; // message
97 size_t msglen; // message length
102 #define CHECK(x) do { if(!(x)) { fprintf(stderr, "CHECK FAILED (%s:%d): %s\n", __FILE__, __LINE__, #x); goto fail; } } while(0)
103 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) { fprintf(stderr, "CHECK FAILED (%s:%d): %s\n", __FILE__, __LINE__, #value); goto fail; } var = val; } while(0)
105 #define CHECK(x) do { if(!(x)) goto fail; } while(0)
106 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
109 #define USING(x) if(!(ctx->x)) return 0
112 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
114 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_INITIALIZE(void)
116 CHECK(d0_bignum_INITIALIZE());
117 CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
118 CHECK_ASSIGN(one, d0_bignum_int(one, 1));
119 CHECK_ASSIGN(four, d0_bignum_int(four, 4));
120 CHECK_ASSIGN(temp0, d0_bignum_int(temp0, 0));
121 CHECK_ASSIGN(temp1, d0_bignum_int(temp1, 0));
122 CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
123 CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
124 CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
130 void d0_blind_id_SHUTDOWN(void)
132 d0_bignum_free(zero);
134 d0_bignum_free(four);
135 d0_bignum_free(temp0);
136 d0_bignum_free(temp1);
137 d0_bignum_free(temp2);
138 d0_bignum_free(temp3);
139 d0_bignum_free(temp4);
140 d0_bignum_SHUTDOWN();
144 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
146 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
147 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
153 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
155 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
156 CHECK(d0_bignum_add(G, G, one));
162 D0_BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
169 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
170 if(d0_bignum_isprime(temp0, 0) == 0)
172 CHECK(d0_dl_get_from_order(G, temp0));
173 if(d0_bignum_isprime(G, 10) == 0)
175 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
184 D0_BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
186 // uses temp0 to temp4
189 int pb = (size + 1)/2;
197 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
198 if(d0_bignum_isprime(temp0, 10) == 0)
200 CHECK(d0_bignum_sub(temp2, temp0, one));
201 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
202 if(!d0_bignum_cmp(temp4, one))
211 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
212 if(!d0_bignum_cmp(temp1, temp0))
218 if(d0_bignum_isprime(temp1, 10) == 0)
220 CHECK(d0_bignum_sub(temp3, temp1, one));
221 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
222 if(!d0_bignum_cmp(temp4, one))
230 CHECK(d0_bignum_mul(n, temp0, temp1));
232 // d = challenge^-1 mod (temp0-1)(temp1-1)
233 CHECK(d0_bignum_mul(temp0, temp2, temp3));
234 CHECK(d0_bignum_mod_inv(d, challenge, temp0));
240 D0_BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
242 // uses temp0 to temp4
245 int pb = (size + 1)/2;
253 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
254 if(d0_bignum_isprime(temp0, 10) == 0)
256 CHECK(d0_bignum_sub(temp2, temp0, one));
257 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
258 if(!d0_bignum_cmp(temp4, one))
267 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
268 if(!d0_bignum_cmp(temp1, temp0))
276 CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
277 if(reject(ctx, pass))
280 if(d0_bignum_isprime(temp1, 10) == 0)
282 CHECK(d0_bignum_sub(temp3, temp1, one));
283 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
284 if(!d0_bignum_cmp(temp4, one))
291 // ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
292 CHECK(d0_bignum_mul(temp0, temp2, temp3));
293 CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
299 D0_WARN_UNUSED_RESULT D0_BOOL d0_longhash_destructive(unsigned char *convbuf, size_t sz, unsigned char *outbuf, size_t outbuflen)
304 while(n > SHA_DIGESTSIZE)
306 memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
307 outbuf += SHA_DIGESTSIZE;
309 for(i = 0; i < sz; ++i)
311 break; // stop until no carry
313 memcpy(outbuf, sha(convbuf, sz), n);
317 D0_WARN_UNUSED_RESULT D0_BOOL d0_longhash_bignum(const d0_bignum_t *in, unsigned char *outbuf, size_t outbuflen)
319 static unsigned char convbuf[1024];
322 CHECK(d0_bignum_export_unsigned(in, convbuf, sizeof(convbuf)) >= 0);
323 sz = (d0_bignum_size(in) + 7) / 8;
324 CHECK(d0_longhash_destructive(convbuf, sz, outbuf, outbuflen));
331 void d0_blind_id_clear(d0_blind_id_t *ctx)
333 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
334 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
335 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
336 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
337 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
338 if(ctx->schnorr_g_to_s) d0_bignum_free(ctx->schnorr_g_to_s);
339 if(ctx->schnorr_H_g_to_s_signature) d0_bignum_free(ctx->schnorr_H_g_to_s_signature);
340 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
341 if(ctx->r) d0_bignum_free(ctx->r);
342 if(ctx->challenge) d0_bignum_free(ctx->challenge);
343 if(ctx->t) d0_bignum_free(ctx->t);
344 if(ctx->g_to_t) d0_bignum_free(ctx->g_to_t);
345 if(ctx->other_g_to_t) d0_bignum_free(ctx->other_g_to_t);
346 memset(ctx, 0, sizeof(*ctx));
349 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
351 d0_blind_id_clear(ctx);
352 if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
353 if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
354 if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
355 if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
356 if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
357 if(src->schnorr_g_to_s) CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mov(NULL, src->schnorr_g_to_s));
358 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));
359 if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
360 if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
361 if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
362 if(src->t) CHECK_ASSIGN(ctx->t, d0_bignum_mov(NULL, src->t));
363 if(src->g_to_t) CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mov(NULL, src->g_to_t));
364 if(src->other_g_to_t) CHECK_ASSIGN(ctx->other_g_to_t, d0_bignum_mov(NULL, src->other_g_to_t));
365 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
366 ctx->msglen = src->msglen;
367 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
370 d0_blind_id_clear(ctx);
374 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_key_fastreject(d0_blind_id_t *ctx, int k, d0_fastreject_function reject, void *pass)
376 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
378 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
379 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
380 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
382 CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
384 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
390 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
392 return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
395 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
397 d0_iobuf_t *in = NULL;
399 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
401 in = d0_iobuf_open_read(inbuf, inbuflen);
403 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
404 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
405 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
406 return d0_iobuf_close(in, NULL);
409 d0_iobuf_close(in, NULL);
413 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
415 d0_iobuf_t *in = NULL;
417 REPLACING(rsa_n); REPLACING(rsa_e);
419 in = d0_iobuf_open_read(inbuf, inbuflen);
420 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
421 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
422 return d0_iobuf_close(in, NULL);
425 d0_iobuf_close(in, NULL);
429 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
431 d0_iobuf_t *out = NULL;
433 USING(rsa_n); USING(rsa_e); USING(rsa_d);
435 out = d0_iobuf_open_write(outbuf, *outbuflen);
436 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
437 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
438 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
439 return d0_iobuf_close(out, outbuflen);
442 d0_iobuf_close(out, outbuflen);
446 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
448 d0_iobuf_t *out = NULL;
450 USING(rsa_n); USING(rsa_e);
452 out = d0_iobuf_open_write(outbuf, *outbuflen);
453 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
454 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
455 return d0_iobuf_close(out, outbuflen);
458 if(!d0_iobuf_close(out, outbuflen))
463 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
465 d0_iobuf_t *out = NULL;
466 static unsigned char convbuf[2048];
467 d0_iobuf_t *conv = NULL;
470 USING(rsa_n); USING(rsa_e);
472 out = d0_iobuf_open_write(outbuf, *outbuflen);
473 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
475 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
476 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
477 CHECK(d0_iobuf_close(conv, &sz));
480 n = (*outbuflen / 4) * 3;
481 if(n > SHA_DIGESTSIZE)
483 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
484 CHECK(d0_iobuf_conv_base64_out(out));
486 return d0_iobuf_close(out, outbuflen);
490 d0_iobuf_close(conv, &sz);
491 d0_iobuf_close(out, outbuflen);
495 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
498 REPLACING(schnorr_G);
500 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
501 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
507 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
509 d0_iobuf_t *in = NULL;
511 REPLACING(schnorr_G);
513 in = d0_iobuf_open_read(inbuf, inbuflen);
514 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
515 return d0_iobuf_close(in, NULL);
518 d0_iobuf_close(in, NULL);
522 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
524 d0_iobuf_t *out = NULL;
528 out = d0_iobuf_open_write(outbuf, *outbuflen);
529 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
530 return d0_iobuf_close(out, outbuflen);
533 d0_iobuf_close(out, outbuflen);
537 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
539 // temps: temp0 = order
541 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s);
543 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
544 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
545 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mod_pow(ctx->schnorr_g_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
546 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
553 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
555 d0_iobuf_t *out = NULL;
556 static unsigned char shabuf[2048];
559 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
560 USING(rsa_n); USING(rsa_e); USING(schnorr_g_to_s);
561 REPLACING(rsa_blind_signature_camouflage);
563 out = d0_iobuf_open_write(outbuf, *outbuflen);
565 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
566 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
568 // we will actually sign HA(4^s) to prevent a malleability attack!
569 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
570 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
571 if(sz > sizeof(shabuf))
573 CHECK(d0_longhash_bignum(temp2, shabuf, sz));
574 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
577 CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
578 CHECK(d0_iobuf_write_bignum(out, temp1));
579 return d0_iobuf_close(out, outbuflen);
582 d0_iobuf_close(out, outbuflen);
586 D0_WARN_UNUSED_RESULT D0_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)
588 d0_iobuf_t *in = NULL;
589 d0_iobuf_t *out = NULL;
591 // temps: temp0 input, temp1 temp0^d
592 USING(rsa_d); USING(rsa_n);
594 in = d0_iobuf_open_read(inbuf, inbuflen);
595 out = d0_iobuf_open_write(outbuf, *outbuflen);
597 CHECK(d0_iobuf_read_bignum(in, temp0));
598 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
599 CHECK(d0_iobuf_write_bignum(out, temp1));
601 d0_iobuf_close(in, NULL);
602 return d0_iobuf_close(out, outbuflen);
605 d0_iobuf_close(in, NULL);
606 d0_iobuf_close(out, outbuflen);
610 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
612 d0_iobuf_t *in = NULL;
614 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
615 USING(rsa_blind_signature_camouflage); USING(rsa_n);
616 REPLACING(schnorr_H_g_to_s_signature);
618 in = d0_iobuf_open_read(inbuf, inbuflen);
620 CHECK(d0_iobuf_read_bignum(in, temp0));
621 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
622 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));
624 return d0_iobuf_close(in, NULL);
627 d0_iobuf_close(in, NULL);
631 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
633 d0_iobuf_t *in = NULL;
635 REPLACING(rsa_blind_signature_camouflage);
637 in = d0_iobuf_open_read(inbuf, inbuflen);
639 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
641 return d0_iobuf_close(in, NULL);
644 d0_iobuf_close(in, NULL);
648 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_id_request_camouflage(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
650 d0_iobuf_t *out = NULL;
652 USING(rsa_blind_signature_camouflage);
654 out = d0_iobuf_open_write(outbuf, *outbuflen);
656 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
658 return d0_iobuf_close(out, outbuflen);
661 d0_iobuf_close(out, outbuflen);
665 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
667 d0_iobuf_t *in = NULL;
669 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
671 in = d0_iobuf_open_read(inbuf, inbuflen);
673 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
674 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
675 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
677 return d0_iobuf_close(in, NULL);
680 d0_iobuf_close(in, NULL);
684 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
686 d0_iobuf_t *in = NULL;
688 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
690 in = d0_iobuf_open_read(inbuf, inbuflen);
692 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
693 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
695 return d0_iobuf_close(in, NULL);
698 d0_iobuf_close(in, NULL);
702 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
704 d0_iobuf_t *out = NULL;
706 USING(schnorr_s); USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
708 out = d0_iobuf_open_write(outbuf, *outbuflen);
710 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
711 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
712 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
714 return d0_iobuf_close(out, outbuflen);
717 d0_iobuf_close(out, outbuflen);
721 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
723 d0_iobuf_t *out = NULL;
725 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
727 out = d0_iobuf_open_write(outbuf, *outbuflen);
729 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
730 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
732 return d0_iobuf_close(out, outbuflen);
735 d0_iobuf_close(out, outbuflen);
739 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL send_modulus, const char *msg, size_t msglen, char *outbuf, size_t *outbuflen)
741 // first run: send 4^s, 4^s signature
742 // 1. get random r, send HASH(4^r)
744 d0_iobuf_t *out = NULL;
745 static unsigned char convbuf[1024];
746 d0_iobuf_t *conv = NULL;
750 // temps: temp0 order, temp0 4^r
753 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
756 REPLACING(r); REPLACING(t); REPLACING(g_to_t);
758 out = d0_iobuf_open_write(outbuf, *outbuflen);
764 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
765 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
766 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
769 // start schnorr ID scheme
770 // generate random number r; x = g^r; send hash of x, remember r, forget x
771 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
773 CHECK_ASSIGN(ctx->r, d0_bignum_int(ctx->r, 4)); // decided by fair dice roll
775 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
778 // initialize Signed Diffie Hellmann
779 // we already have the group order in temp1
781 CHECK_ASSIGN(ctx->t, d0_bignum_int(ctx->t, 4)); // decided by fair dice roll
783 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
785 // can we SOMEHOW do this with just one mod_pow?
787 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
788 CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mod_pow(ctx->g_to_t, four, ctx->t, ctx->schnorr_G));
791 // hash it, hash it, everybody hash it
792 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
793 CHECK(d0_iobuf_write_bignum(conv, temp0));
794 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
795 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
796 CHECK(d0_iobuf_write_bignum(conv, temp0));
797 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
798 d0_iobuf_close(conv, &sz);
800 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
801 CHECK(d0_iobuf_write_packet(out, msg, msglen));
803 return d0_iobuf_close(out, outbuflen);
806 d0_iobuf_close(out, outbuflen);
810 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL recv_modulus, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen, D0_BOOL *status)
811 // first run: get 4^s, 4^s signature
814 // 3. send challenge challenge of SCHNORR_BITS
816 d0_iobuf_t *in = NULL;
817 d0_iobuf_t *out = NULL;
818 static unsigned char shabuf[2048];
821 // temps: temp0 order, temp0 signature check
824 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
826 REPLACING(schnorr_G);
832 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
835 USING(rsa_e); USING(rsa_n);
836 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r); REPLACING(t);
838 in = d0_iobuf_open_read(inbuf, inbuflen);
839 out = d0_iobuf_open_write(outbuf, *outbuflen);
845 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
846 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
847 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
849 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
850 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
851 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
852 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
853 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
854 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
856 // check signature of key (t = k^d, so, t^challenge = k)
857 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
859 // we will actually sign SHA(4^s) to prevent a malleability attack!
860 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
861 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
862 if(sz > sizeof(shabuf))
864 CHECK(d0_longhash_bignum(temp2, shabuf, sz));
865 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
867 // + 7 / 8 is too large, so let's mod it
868 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
871 if(d0_bignum_cmp(temp0, temp1))
873 // accept the key anyway, but mark as failed signature! will later return 0 in status
874 CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
878 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
879 ctx->msglen = MSGSIZE;
880 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
884 CHECK_ASSIGN(ctx->challenge, d0_bignum_int(ctx->challenge, 4)); // decided by fair dice roll
886 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
888 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
890 // Diffie Hellmann send
891 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
893 CHECK_ASSIGN(ctx->t, d0_bignum_int(ctx->t, 4)); // decided by fair dice roll
895 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
897 CHECK(d0_bignum_mod_pow(temp0, four, ctx->t, ctx->schnorr_G));
898 CHECK(d0_iobuf_write_bignum(out, temp0));
901 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
903 d0_iobuf_close(in, NULL);
904 return d0_iobuf_close(out, outbuflen);
907 d0_iobuf_close(in, NULL);
908 d0_iobuf_close(out, outbuflen);
912 D0_WARN_UNUSED_RESULT D0_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)
913 // 1. read challenge challenge of SCHNORR_BITS
914 // 2. reply with r + s * challenge mod order
916 d0_iobuf_t *in = NULL;
917 d0_iobuf_t *out = NULL;
919 // temps: 0 order, 1 prod, 2 y, 3 challenge
920 REPLACING(other_g_to_t); REPLACING(t);
921 USING(schnorr_G); USING(schnorr_s); USING(r); USING(g_to_t);
923 in = d0_iobuf_open_read(inbuf, inbuflen);
924 out = d0_iobuf_open_write(outbuf, *outbuflen);
926 CHECK(d0_iobuf_read_bignum(in, temp3));
927 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
928 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
930 // send response for schnorr ID scheme
931 // i.challenge. r + ctx->schnorr_s * temp3
932 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
933 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
934 #ifdef D0_BLIND_ID_POSITIVE_PROTOCOL
935 CHECK(d0_bignum_mod_add(temp2, ctx->r, temp1, temp0));
937 CHECK(d0_bignum_mod_sub(temp2, ctx->r, temp1, temp0));
939 CHECK(d0_iobuf_write_bignum(out, temp2));
941 // Diffie Hellmann recv
942 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
943 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
944 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
945 // Diffie Hellmann send
946 CHECK(d0_iobuf_write_bignum(out, ctx->g_to_t));
948 d0_iobuf_close(in, NULL);
949 return d0_iobuf_close(out, outbuflen);
952 d0_iobuf_close(in, NULL);
953 d0_iobuf_close(out, outbuflen);
957 D0_WARN_UNUSED_RESULT D0_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, D0_BOOL *status)
958 // 1. read y = r + s * challenge mod order
959 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
960 // (check using H(g^r) which we know)
962 d0_iobuf_t *in = NULL;
963 static unsigned char convbuf[1024];
964 d0_iobuf_t *conv = NULL;
967 // temps: 0 y 1 order
968 USING(challenge); USING(schnorr_G);
969 REPLACING(other_g_to_t);
971 in = d0_iobuf_open_read(inbuf, inbuflen);
973 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
974 CHECK(d0_iobuf_read_bignum(in, temp0));
975 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
976 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
978 // verify schnorr ID scheme
979 #ifdef D0_BLIND_ID_POSITIVE_PROTOCOL
980 // we need 4^r = 4^temp0 (g^s)^-challenge
981 CHECK(d0_bignum_mod_inv(temp1, ctx->schnorr_g_to_s, ctx->schnorr_G));
982 CHECK(d0_bignum_mod_pow(temp2, temp1, ctx->challenge, ctx->schnorr_G));
984 // we need 4^r = 4^temp0 (g^s)^challenge
985 CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_g_to_s, ctx->challenge, ctx->schnorr_G));
987 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
988 CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G));
990 // Diffie Hellmann recv
991 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
992 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
993 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
995 // hash it, hash it, everybody hash it
996 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
997 CHECK(d0_iobuf_write_bignum(conv, temp3));
998 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
999 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
1000 CHECK(d0_iobuf_write_bignum(conv, temp3));
1001 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
1002 d0_iobuf_close(conv, &sz);
1004 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
1006 // FAIL (not owned by player)
1011 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
1013 if(ctx->msglen <= *msglen)
1014 memcpy(msg, ctx->msg, ctx->msglen);
1016 memcpy(msg, ctx->msg, *msglen);
1017 *msglen = ctx->msglen;
1019 d0_iobuf_close(in, NULL);
1023 d0_iobuf_close(in, NULL);
1027 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_generate_missing_signature(d0_blind_id_t *ctx)
1030 static unsigned char shabuf[2048];
1032 REPLACING(schnorr_H_g_to_s_signature);
1033 USING(schnorr_g_to_s); USING(rsa_d); USING(rsa_n);
1035 // we will actually sign SHA(4^s) to prevent a malleability attack!
1036 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
1037 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
1038 if(sz > sizeof(shabuf))
1039 sz = sizeof(shabuf);
1040 CHECK(d0_longhash_bignum(temp2, shabuf, sz));
1041 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
1043 // + 7 / 8 is too large, so let's mod it
1044 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
1045 CHECK(d0_bignum_mod_pow(ctx->schnorr_H_g_to_s_signature, temp1, ctx->rsa_d, ctx->rsa_n));
1052 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_sign_with_private_id_sign_internal(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL send_modulus, D0_BOOL with_msg, const char *message, size_t msglen, char *outbuf, size_t *outbuflen)
1054 d0_iobuf_t *out = NULL;
1055 static unsigned char convbuf[1024];
1056 static unsigned char shabuf[1024];
1057 d0_iobuf_t *conv = NULL;
1062 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
1068 out = d0_iobuf_open_write(outbuf, *outbuflen);
1074 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
1075 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
1076 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
1079 // start schnorr SIGNATURE scheme
1080 // generate random number r; x = g^r; send hash of H(m||r), remember r, forget x
1081 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
1082 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
1083 CHECK(d0_bignum_mod_pow(temp1, four, ctx->r, ctx->schnorr_G));
1085 // hash it, hash it, everybody hash it
1086 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
1087 CHECK(d0_iobuf_write_packet(conv, message, msglen));
1088 CHECK(d0_iobuf_write_bignum(conv, temp1));
1089 d0_iobuf_close(conv, &sz);
1091 CHECK(d0_longhash_destructive(convbuf, sz, shabuf, (d0_bignum_size(temp0) + 7) / 8));
1092 CHECK(d0_bignum_import_unsigned(temp2, shabuf, (d0_bignum_size(temp0) + 7) / 8));
1093 CHECK(d0_iobuf_write_bignum(out, temp2));
1095 // multiply with secret, sub k, modulo order
1096 CHECK(d0_bignum_mod_mul(temp1, temp2, ctx->schnorr_s, temp0));
1097 #ifdef D0_BLIND_ID_POSITIVE_PROTOCOL
1098 CHECK(d0_bignum_mod_add(temp2, ctx->r, temp1, temp0));
1100 CHECK(d0_bignum_mod_sub(temp2, ctx->r, temp1, temp0));
1102 CHECK(d0_iobuf_write_bignum(out, temp2));
1104 // write the message itself
1106 CHECK(d0_iobuf_write_packet(out, message, msglen));
1108 return d0_iobuf_close(out, outbuflen);
1111 d0_iobuf_close(out, outbuflen);
1114 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_sign_with_private_id_sign(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL send_modulus, const char *message, size_t msglen, char *outbuf, size_t *outbuflen)
1116 return d0_blind_id_sign_with_private_id_sign_internal(ctx, is_first, send_modulus, 1, message, msglen, outbuf, outbuflen);
1118 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_sign_with_private_id_sign_detached(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL send_modulus, const char *message, size_t msglen, char *outbuf, size_t *outbuflen)
1120 return d0_blind_id_sign_with_private_id_sign_internal(ctx, is_first, send_modulus, 0, message, msglen, outbuf, outbuflen);
1123 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_sign_with_private_id_verify_internal(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL recv_modulus, D0_BOOL with_msg, const char *inbuf, size_t inbuflen, char *msg, size_t *msglen, D0_BOOL *status)
1125 d0_iobuf_t *in = NULL;
1126 d0_iobuf_t *conv = NULL;
1127 static unsigned char convbuf[2048];
1128 static unsigned char shabuf[2048];
1133 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
1135 REPLACING(schnorr_G);
1141 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
1144 USING(rsa_e); USING(rsa_n);
1146 in = d0_iobuf_open_read(inbuf, inbuflen);
1152 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
1153 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
1154 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
1156 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
1157 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
1158 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
1159 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
1160 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
1161 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
1163 // check signature of key (t = k^d, so, t^challenge = k)
1164 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
1166 // we will actually sign SHA(4^s) to prevent a malleability attack!
1167 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
1168 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
1169 if(sz > sizeof(shabuf))
1170 sz = sizeof(shabuf);
1171 CHECK(d0_longhash_bignum(temp2, shabuf, sz));
1172 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
1174 // + 7 / 8 is too large, so let's mod it
1175 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
1178 if(d0_bignum_cmp(temp0, temp1))
1180 // accept the key anyway, but mark as failed signature! will later return 0 in status
1181 CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
1185 CHECK(d0_dl_get_order(temp4, ctx->schnorr_G));
1186 CHECK(d0_iobuf_read_bignum(in, temp0)); // e == H(m || g^r)
1187 CHECK(d0_iobuf_read_bignum(in, temp1)); // x == (r - s*e) mod |G|
1189 CHECK(d0_iobuf_read_packet(in, msg, msglen));
1191 // VERIFY: g^x * (g^s)^-e = g^(x - s*e) = g^r
1193 // verify schnorr ID scheme
1194 // we need g^r = g^x (g^s)^e
1195 CHECK(d0_bignum_mod_pow(temp2, four, temp1, ctx->schnorr_G));
1196 #ifdef D0_BLIND_ID_POSITIVE_PROTOCOL
1197 CHECK(d0_bignum_mod_inv(temp3, ctx->schnorr_g_to_s, ctx->schnorr_G));
1198 CHECK(d0_bignum_mod_pow(temp1, temp3, temp0, ctx->schnorr_G));
1200 CHECK(d0_bignum_mod_pow(temp1, ctx->schnorr_g_to_s, temp0, ctx->schnorr_G));
1202 CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G)); // temp3 now is g^r
1204 // hash it, hash it, everybody hash it
1205 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
1206 CHECK(d0_iobuf_write_packet(conv, msg, *msglen));
1207 CHECK(d0_iobuf_write_bignum(conv, temp3));
1208 d0_iobuf_close(conv, &sz);
1210 CHECK(d0_longhash_destructive(convbuf, sz, shabuf, (d0_bignum_size(temp4) + 7) / 8));
1211 CHECK(d0_bignum_import_unsigned(temp1, shabuf, (d0_bignum_size(temp4) + 7) / 8));
1214 CHECK(!d0_bignum_cmp(temp0, temp1));
1217 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
1219 d0_iobuf_close(in, NULL);
1223 d0_iobuf_close(in, NULL);
1226 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_sign_with_private_id_verify(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL recv_modulus, const char *inbuf, size_t inbuflen, char *msg, size_t *msglen, D0_BOOL *status)
1228 return d0_blind_id_sign_with_private_id_verify_internal(ctx, is_first, recv_modulus, 1, inbuf, inbuflen, msg, msglen, status);
1230 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_sign_with_private_id_verify_detached(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL recv_modulus, const char *inbuf, size_t inbuflen, const char *msg, size_t msglen, D0_BOOL *status)
1232 return d0_blind_id_sign_with_private_id_verify_internal(ctx, is_first, recv_modulus, 0, inbuf, inbuflen, (char *) msg, &msglen, status);
1235 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
1237 d0_iobuf_t *out = NULL;
1238 static unsigned char convbuf[1024];
1239 d0_iobuf_t *conv = NULL;
1244 USING(schnorr_g_to_s);
1246 out = d0_iobuf_open_write(outbuf, *outbuflen);
1247 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
1249 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
1250 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
1251 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_g_to_s));
1252 CHECK(d0_iobuf_close(conv, &sz));
1255 n = (*outbuflen / 4) * 3;
1256 if(n > SHA_DIGESTSIZE)
1258 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
1259 CHECK(d0_iobuf_conv_base64_out(out));
1261 return d0_iobuf_close(out, outbuflen);
1265 d0_iobuf_close(conv, &sz);
1266 d0_iobuf_close(out, outbuflen);
1270 D0_BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
1272 USING(t); USING(other_g_to_t); USING(schnorr_G);
1274 // temps: temp0 result
1275 CHECK(d0_bignum_mod_pow(temp0, ctx->other_g_to_t, ctx->t, ctx->schnorr_G));
1276 return d0_longhash_bignum(temp0, (unsigned char *) outbuf, *outbuflen);
1282 d0_blind_id_t *d0_blind_id_new(void)
1284 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
1285 memset(b, 0, sizeof(*b));
1289 void d0_blind_id_free(d0_blind_id_t *a)
1291 d0_blind_id_clear(a);
1295 void d0_blind_id_util_sha256(char *out, const char *in, size_t n)
1298 SHA256_Init(&context);
1299 SHA256_Update(&context, (const unsigned char *) in, n);
1300 return SHA256_Final((unsigned char *) out, &context);