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
100 #define CHECK(x) do { if(!(x)) goto fail; } while(0)
101 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
102 #define MPCHECK(x) do { if(!failed) if(!(x)) failed = 1; } while(0)
103 #define MPCHECK_ASSIGN(var, value) do { if(!failed) { d0_bignum_t *val; val = value; if(val) var = val; else failed = 1; } } while(0)
105 #define USING(x) if(!(ctx->x)) return 0
108 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
110 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_INITIALIZE(void)
112 CHECK(d0_bignum_INITIALIZE());
113 CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
114 CHECK_ASSIGN(one, d0_bignum_int(one, 1));
115 CHECK_ASSIGN(four, d0_bignum_int(four, 4));
116 CHECK_ASSIGN(temp0, d0_bignum_int(temp0, 0));
117 CHECK_ASSIGN(temp1, d0_bignum_int(temp1, 0));
118 CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
119 CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
120 CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
126 void d0_blind_id_SHUTDOWN(void)
128 d0_bignum_free(zero);
130 d0_bignum_free(four);
131 d0_bignum_free(temp0);
132 d0_bignum_free(temp1);
133 d0_bignum_free(temp2);
134 d0_bignum_free(temp3);
135 d0_bignum_free(temp4);
136 d0_bignum_SHUTDOWN();
140 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
142 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
143 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
149 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
151 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
152 CHECK(d0_bignum_add(G, G, one));
158 D0_BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
165 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
166 if(d0_bignum_isprime(temp0, 0) == 0)
168 CHECK(d0_dl_get_from_order(G, temp0));
169 if(d0_bignum_isprime(G, 10) == 0)
171 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
180 D0_BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
182 // uses temp0 to temp4
185 int pb = (size + 1)/2;
193 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
194 if(d0_bignum_isprime(temp0, 10) == 0)
196 CHECK(d0_bignum_sub(temp2, temp0, one));
197 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
198 if(!d0_bignum_cmp(temp4, one))
207 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
208 if(!d0_bignum_cmp(temp1, temp0))
214 if(d0_bignum_isprime(temp1, 10) == 0)
216 CHECK(d0_bignum_sub(temp3, temp1, one));
217 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
218 if(!d0_bignum_cmp(temp4, one))
226 CHECK(d0_bignum_mul(n, temp0, temp1));
228 // d = challenge^-1 mod (temp0-1)(temp1-1)
229 CHECK(d0_bignum_mul(temp0, temp2, temp3));
230 CHECK(d0_bignum_mod_inv(d, challenge, temp0));
236 D0_BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
238 // uses temp0 to temp4
241 int pb = (size + 1)/2;
249 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
250 if(d0_bignum_isprime(temp0, 10) == 0)
252 CHECK(d0_bignum_sub(temp2, temp0, one));
253 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
254 if(!d0_bignum_cmp(temp4, one))
263 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
264 if(!d0_bignum_cmp(temp1, temp0))
272 CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
273 if(reject(ctx, pass))
276 if(d0_bignum_isprime(temp1, 10) == 0)
278 CHECK(d0_bignum_sub(temp3, temp1, one));
279 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
280 if(!d0_bignum_cmp(temp4, one))
287 // ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
288 CHECK(d0_bignum_mul(temp0, temp2, temp3));
289 CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
295 D0_WARN_UNUSED_RESULT D0_BOOL d0_longhash_destructive(unsigned char *convbuf, size_t sz, unsigned char *outbuf, size_t outbuflen)
300 while(n > SHA_DIGESTSIZE)
302 memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
303 outbuf += SHA_DIGESTSIZE;
305 for(i = 0; i < sz; ++i)
307 break; // stop until no carry
309 memcpy(outbuf, sha(convbuf, sz), n);
313 D0_WARN_UNUSED_RESULT D0_BOOL d0_longhash_bignum(const d0_bignum_t *in, unsigned char *outbuf, size_t outbuflen)
315 static unsigned char convbuf[1024];
318 CHECK(d0_bignum_export_unsigned(in, convbuf, sizeof(convbuf)) >= 0);
319 sz = (d0_bignum_size(in) + 7) / 8;
320 CHECK(d0_longhash_destructive(convbuf, sz, outbuf, outbuflen));
327 void d0_blind_id_clear(d0_blind_id_t *ctx)
329 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
330 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
331 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
332 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
333 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
334 if(ctx->schnorr_g_to_s) d0_bignum_free(ctx->schnorr_g_to_s);
335 if(ctx->schnorr_H_g_to_s_signature) d0_bignum_free(ctx->schnorr_H_g_to_s_signature);
336 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
337 if(ctx->r) d0_bignum_free(ctx->r);
338 if(ctx->challenge) d0_bignum_free(ctx->challenge);
339 if(ctx->t) d0_bignum_free(ctx->t);
340 if(ctx->g_to_t) d0_bignum_free(ctx->g_to_t);
341 if(ctx->other_g_to_t) d0_bignum_free(ctx->other_g_to_t);
342 memset(ctx, 0, sizeof(*ctx));
345 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
347 d0_blind_id_clear(ctx);
348 if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
349 if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
350 if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
351 if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
352 if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
353 if(src->schnorr_g_to_s) CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mov(NULL, src->schnorr_g_to_s));
354 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));
355 if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
356 if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
357 if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
358 if(src->t) CHECK_ASSIGN(ctx->t, d0_bignum_mov(NULL, src->t));
359 if(src->g_to_t) CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mov(NULL, src->g_to_t));
360 if(src->other_g_to_t) CHECK_ASSIGN(ctx->other_g_to_t, d0_bignum_mov(NULL, src->other_g_to_t));
361 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
362 ctx->msglen = src->msglen;
363 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
366 d0_blind_id_clear(ctx);
370 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)
372 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
374 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
375 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
376 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
378 CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
380 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
386 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
388 return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
391 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
393 d0_iobuf_t *in = NULL;
395 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
397 in = d0_iobuf_open_read(inbuf, inbuflen);
399 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
400 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
401 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
402 return d0_iobuf_close(in, NULL);
405 d0_iobuf_close(in, NULL);
409 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
411 d0_iobuf_t *in = NULL;
413 REPLACING(rsa_n); REPLACING(rsa_e);
415 in = d0_iobuf_open_read(inbuf, inbuflen);
416 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
417 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
418 return d0_iobuf_close(in, NULL);
421 d0_iobuf_close(in, NULL);
425 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
427 d0_iobuf_t *out = NULL;
429 USING(rsa_n); USING(rsa_e); USING(rsa_d);
431 out = d0_iobuf_open_write(outbuf, *outbuflen);
432 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
433 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
434 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
435 return d0_iobuf_close(out, outbuflen);
438 d0_iobuf_close(out, outbuflen);
442 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
444 d0_iobuf_t *out = NULL;
446 USING(rsa_n); USING(rsa_e);
448 out = d0_iobuf_open_write(outbuf, *outbuflen);
449 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
450 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
451 return d0_iobuf_close(out, outbuflen);
454 if(!d0_iobuf_close(out, outbuflen))
459 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
461 d0_iobuf_t *out = NULL;
462 static unsigned char convbuf[2048];
463 d0_iobuf_t *conv = NULL;
466 USING(rsa_n); USING(rsa_e);
468 out = d0_iobuf_open_write(outbuf, *outbuflen);
469 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
471 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
472 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
473 CHECK(d0_iobuf_close(conv, &sz));
476 n = (*outbuflen / 4) * 3;
477 if(n > SHA_DIGESTSIZE)
479 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
480 CHECK(d0_iobuf_conv_base64_out(out));
482 return d0_iobuf_close(out, outbuflen);
486 d0_iobuf_close(conv, &sz);
487 d0_iobuf_close(out, outbuflen);
491 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
494 REPLACING(schnorr_G);
496 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
497 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
503 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
505 d0_iobuf_t *in = NULL;
507 REPLACING(schnorr_G);
509 in = d0_iobuf_open_read(inbuf, inbuflen);
510 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
511 return d0_iobuf_close(in, NULL);
514 d0_iobuf_close(in, NULL);
518 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
520 d0_iobuf_t *out = NULL;
524 out = d0_iobuf_open_write(outbuf, *outbuflen);
525 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
526 return d0_iobuf_close(out, outbuflen);
529 d0_iobuf_close(out, outbuflen);
533 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
535 // temps: temp0 = order
537 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s);
539 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
540 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
541 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mod_pow(ctx->schnorr_g_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
542 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
549 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
551 d0_iobuf_t *out = NULL;
552 static unsigned char shabuf[2048];
555 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
556 USING(rsa_n); USING(rsa_e); USING(schnorr_g_to_s);
557 REPLACING(rsa_blind_signature_camouflage);
559 out = d0_iobuf_open_write(outbuf, *outbuflen);
561 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
562 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
564 // we will actually sign HA(4^s) to prevent a malleability attack!
565 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
566 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
567 if(sz > sizeof(shabuf))
569 CHECK(d0_longhash_bignum(temp2, shabuf, sz));
570 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
573 CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
574 CHECK(d0_iobuf_write_bignum(out, temp1));
575 return d0_iobuf_close(out, outbuflen);
578 d0_iobuf_close(out, outbuflen);
582 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)
584 d0_iobuf_t *in = NULL;
585 d0_iobuf_t *out = NULL;
587 // temps: temp0 input, temp1 temp0^d
588 USING(rsa_d); USING(rsa_n);
590 in = d0_iobuf_open_read(inbuf, inbuflen);
591 out = d0_iobuf_open_write(outbuf, *outbuflen);
593 CHECK(d0_iobuf_read_bignum(in, temp0));
594 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
595 CHECK(d0_iobuf_write_bignum(out, temp1));
597 d0_iobuf_close(in, NULL);
598 return d0_iobuf_close(out, outbuflen);
601 d0_iobuf_close(in, NULL);
602 d0_iobuf_close(out, outbuflen);
606 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
608 d0_iobuf_t *in = NULL;
610 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
611 USING(rsa_blind_signature_camouflage); USING(rsa_n);
612 REPLACING(schnorr_H_g_to_s_signature);
614 in = d0_iobuf_open_read(inbuf, inbuflen);
616 CHECK(d0_iobuf_read_bignum(in, temp0));
617 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
618 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));
620 return d0_iobuf_close(in, NULL);
623 d0_iobuf_close(in, NULL);
627 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)
629 d0_iobuf_t *in = NULL;
631 REPLACING(rsa_blind_signature_camouflage);
633 in = d0_iobuf_open_read(inbuf, inbuflen);
635 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
637 return d0_iobuf_close(in, NULL);
640 d0_iobuf_close(in, NULL);
644 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)
646 d0_iobuf_t *out = NULL;
648 USING(rsa_blind_signature_camouflage);
650 out = d0_iobuf_open_write(outbuf, *outbuflen);
652 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
654 return d0_iobuf_close(out, outbuflen);
657 d0_iobuf_close(out, outbuflen);
661 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
663 d0_iobuf_t *in = NULL;
665 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
667 in = d0_iobuf_open_read(inbuf, inbuflen);
669 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
670 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
671 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
673 return d0_iobuf_close(in, NULL);
676 d0_iobuf_close(in, NULL);
680 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
682 d0_iobuf_t *in = NULL;
684 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
686 in = d0_iobuf_open_read(inbuf, inbuflen);
688 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
689 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
691 return d0_iobuf_close(in, NULL);
694 d0_iobuf_close(in, NULL);
698 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
700 d0_iobuf_t *out = NULL;
702 USING(schnorr_s); USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
704 out = d0_iobuf_open_write(outbuf, *outbuflen);
706 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
707 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
708 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
710 return d0_iobuf_close(out, outbuflen);
713 d0_iobuf_close(out, outbuflen);
717 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
719 d0_iobuf_t *out = NULL;
721 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
723 out = d0_iobuf_open_write(outbuf, *outbuflen);
725 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
726 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
728 return d0_iobuf_close(out, outbuflen);
731 d0_iobuf_close(out, outbuflen);
735 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)
737 // first run: send 4^s, 4^s signature
738 // 1. get random r, send HASH(4^r)
740 d0_iobuf_t *out = NULL;
741 static unsigned char convbuf[1024];
742 d0_iobuf_t *conv = NULL;
746 // temps: temp0 order, temp0 4^r
749 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
752 REPLACING(r); REPLACING(t); REPLACING(g_to_t);
754 out = d0_iobuf_open_write(outbuf, *outbuflen);
760 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
761 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
762 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
765 // start schnorr ID scheme
766 // generate random number r; x = g^r; send hash of x, remember r, forget x
767 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
769 CHECK_ASSIGN(ctx->r, d0_bignum_int(ctx->r, 4)); // decided by fair dice roll
771 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
774 // initialize Signed Diffie Hellmann
775 // we already have the group order in temp1
777 CHECK_ASSIGN(ctx->t, d0_bignum_int(ctx->t, 4)); // decided by fair dice roll
779 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
781 // can we SOMEHOW do this with just one mod_pow?
783 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
784 CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mod_pow(ctx->g_to_t, four, ctx->t, ctx->schnorr_G));
787 // hash it, hash it, everybody hash it
788 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
789 CHECK(d0_iobuf_write_bignum(conv, temp0));
790 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
791 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
792 CHECK(d0_iobuf_write_bignum(conv, temp0));
793 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
794 d0_iobuf_close(conv, &sz);
796 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
797 CHECK(d0_iobuf_write_packet(out, msg, msglen));
799 return d0_iobuf_close(out, outbuflen);
802 d0_iobuf_close(out, outbuflen);
806 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)
807 // first run: get 4^s, 4^s signature
810 // 3. send challenge challenge of SCHNORR_BITS
812 d0_iobuf_t *in = NULL;
813 d0_iobuf_t *out = NULL;
814 static unsigned char shabuf[2048];
817 // temps: temp0 order, temp0 signature check
820 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
822 REPLACING(schnorr_G);
828 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
831 USING(rsa_e); USING(rsa_n);
832 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r); REPLACING(t);
834 in = d0_iobuf_open_read(inbuf, inbuflen);
835 out = d0_iobuf_open_write(outbuf, *outbuflen);
841 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
842 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
843 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
845 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
846 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
847 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
848 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
849 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
850 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
852 // check signature of key (t = k^d, so, t^challenge = k)
853 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
855 // we will actually sign SHA(4^s) to prevent a malleability attack!
856 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
857 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
858 if(sz > sizeof(shabuf))
860 CHECK(d0_longhash_bignum(temp2, shabuf, sz));
861 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
863 // + 7 / 8 is too large, so let's mod it
864 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
867 if(d0_bignum_cmp(temp0, temp1))
869 // accept the key anyway, but mark as failed signature! will later return 0 in status
870 CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
874 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
875 ctx->msglen = MSGSIZE;
876 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
880 CHECK_ASSIGN(ctx->challenge, d0_bignum_int(ctx->challenge, 4)); // decided by fair dice roll
882 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
884 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
886 // Diffie Hellmann send
887 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
889 CHECK_ASSIGN(ctx->t, d0_bignum_int(ctx->t, 4)); // decided by fair dice roll
891 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
893 CHECK(d0_bignum_mod_pow(temp0, four, ctx->t, ctx->schnorr_G));
894 CHECK(d0_iobuf_write_bignum(out, temp0));
897 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
899 d0_iobuf_close(in, NULL);
900 return d0_iobuf_close(out, outbuflen);
903 d0_iobuf_close(in, NULL);
904 d0_iobuf_close(out, outbuflen);
908 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)
909 // 1. read challenge challenge of SCHNORR_BITS
910 // 2. reply with r + s * challenge mod order
912 d0_iobuf_t *in = NULL;
913 d0_iobuf_t *out = NULL;
915 // temps: 0 order, 1 prod, 2 y, 3 challenge
916 REPLACING(other_g_to_t); REPLACING(t);
917 USING(schnorr_G); USING(schnorr_s); USING(r); USING(g_to_t);
919 in = d0_iobuf_open_read(inbuf, inbuflen);
920 out = d0_iobuf_open_write(outbuf, *outbuflen);
922 CHECK(d0_iobuf_read_bignum(in, temp3));
923 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
924 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
926 // send response for schnorr ID scheme
927 // i.challenge. r + ctx->schnorr_s * temp3
928 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
929 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
930 #ifdef D0_BLIND_ID_POSITIVE_PROTOCOL
931 CHECK(d0_bignum_mod_add(temp2, ctx->r, temp1, temp0));
933 CHECK(d0_bignum_mod_sub(temp2, ctx->r, temp1, temp0));
935 CHECK(d0_iobuf_write_bignum(out, temp2));
937 // Diffie Hellmann recv
938 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
939 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
940 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
941 // Diffie Hellmann send
942 CHECK(d0_iobuf_write_bignum(out, ctx->g_to_t));
944 d0_iobuf_close(in, NULL);
945 return d0_iobuf_close(out, outbuflen);
948 d0_iobuf_close(in, NULL);
949 d0_iobuf_close(out, outbuflen);
953 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)
954 // 1. read y = r + s * challenge mod order
955 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
956 // (check using H(g^r) which we know)
958 d0_iobuf_t *in = NULL;
959 static unsigned char convbuf[1024];
960 d0_iobuf_t *conv = NULL;
963 // temps: 0 y 1 order
964 USING(challenge); USING(schnorr_G);
965 REPLACING(other_g_to_t);
967 in = d0_iobuf_open_read(inbuf, inbuflen);
969 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
970 CHECK(d0_iobuf_read_bignum(in, temp0));
971 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
972 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
974 // verify schnorr ID scheme
975 #ifdef D0_BLIND_ID_POSITIVE_PROTOCOL
976 // we need 4^r = 4^temp0 (g^s)^-challenge
977 CHECK(d0_bignum_mod_inv(temp1, ctx->schnorr_g_to_s, ctx->schnorr_G));
978 CHECK(d0_bignum_mod_pow(temp2, temp1, ctx->challenge, ctx->schnorr_G));
980 // we need 4^r = 4^temp0 (g^s)^challenge
981 CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_g_to_s, ctx->challenge, ctx->schnorr_G));
983 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
984 CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G));
986 // Diffie Hellmann recv
987 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
988 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
989 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
991 // hash it, hash it, everybody hash it
992 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
993 CHECK(d0_iobuf_write_bignum(conv, temp3));
994 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
995 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
996 CHECK(d0_iobuf_write_bignum(conv, temp3));
997 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
998 d0_iobuf_close(conv, &sz);
1000 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
1002 // FAIL (not owned by player)
1007 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
1009 if(ctx->msglen <= *msglen)
1010 memcpy(msg, ctx->msg, ctx->msglen);
1012 memcpy(msg, ctx->msg, *msglen);
1013 *msglen = ctx->msglen;
1015 d0_iobuf_close(in, NULL);
1019 d0_iobuf_close(in, NULL);
1023 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_generate_missing_signature(d0_blind_id_t *ctx)
1026 static unsigned char shabuf[2048];
1028 REPLACING(schnorr_H_g_to_s_signature);
1029 USING(schnorr_g_to_s); USING(rsa_d); USING(rsa_n);
1031 // we will actually sign SHA(4^s) to prevent a malleability attack!
1032 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
1033 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
1034 if(sz > sizeof(shabuf))
1035 sz = sizeof(shabuf);
1036 CHECK(d0_longhash_bignum(temp2, shabuf, sz));
1037 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
1039 // + 7 / 8 is too large, so let's mod it
1040 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
1041 CHECK(d0_bignum_mod_pow(ctx->schnorr_H_g_to_s_signature, temp1, ctx->rsa_d, ctx->rsa_n));
1048 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)
1050 d0_iobuf_t *out = NULL;
1051 static unsigned char convbuf[1024];
1052 static unsigned char shabuf[1024];
1053 d0_iobuf_t *conv = NULL;
1058 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
1064 out = d0_iobuf_open_write(outbuf, *outbuflen);
1070 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
1071 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
1072 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
1075 // start schnorr SIGNATURE scheme
1076 // generate random number r; x = g^r; send hash of H(m||r), remember r, forget x
1077 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
1078 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
1079 CHECK(d0_bignum_mod_pow(temp1, four, ctx->r, ctx->schnorr_G));
1081 // hash it, hash it, everybody hash it
1082 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
1083 CHECK(d0_iobuf_write_packet(conv, message, msglen));
1084 CHECK(d0_iobuf_write_bignum(conv, temp1));
1085 d0_iobuf_close(conv, &sz);
1087 CHECK(d0_longhash_destructive(convbuf, sz, shabuf, (d0_bignum_size(temp0) + 7) / 8));
1088 CHECK(d0_bignum_import_unsigned(temp2, shabuf, (d0_bignum_size(temp0) + 7) / 8));
1089 CHECK(d0_iobuf_write_bignum(out, temp2));
1091 // multiply with secret, sub k, modulo order
1092 CHECK(d0_bignum_mod_mul(temp1, temp2, ctx->schnorr_s, temp0));
1093 #ifdef D0_BLIND_ID_POSITIVE_PROTOCOL
1094 CHECK(d0_bignum_mod_add(temp2, ctx->r, temp1, temp0));
1096 CHECK(d0_bignum_mod_sub(temp2, ctx->r, temp1, temp0));
1098 CHECK(d0_iobuf_write_bignum(out, temp2));
1100 // write the message itself
1102 CHECK(d0_iobuf_write_packet(out, message, msglen));
1104 return d0_iobuf_close(out, outbuflen);
1107 d0_iobuf_close(out, outbuflen);
1110 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)
1112 return d0_blind_id_sign_with_private_id_sign_internal(ctx, is_first, send_modulus, 1, message, msglen, outbuf, outbuflen);
1114 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)
1116 return d0_blind_id_sign_with_private_id_sign_internal(ctx, is_first, send_modulus, 0, message, msglen, outbuf, outbuflen);
1119 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)
1121 d0_iobuf_t *in = NULL;
1122 d0_iobuf_t *conv = NULL;
1123 static unsigned char convbuf[2048];
1124 static unsigned char shabuf[2048];
1129 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
1131 REPLACING(schnorr_G);
1137 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
1140 USING(rsa_e); USING(rsa_n);
1142 in = d0_iobuf_open_read(inbuf, inbuflen);
1148 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
1149 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
1150 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
1152 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
1153 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
1154 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
1155 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
1156 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
1157 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
1159 // check signature of key (t = k^d, so, t^challenge = k)
1160 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
1162 // we will actually sign SHA(4^s) to prevent a malleability attack!
1163 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
1164 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
1165 if(sz > sizeof(shabuf))
1166 sz = sizeof(shabuf);
1167 CHECK(d0_longhash_bignum(temp2, shabuf, sz));
1168 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
1170 // + 7 / 8 is too large, so let's mod it
1171 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
1174 if(d0_bignum_cmp(temp0, temp1))
1176 // accept the key anyway, but mark as failed signature! will later return 0 in status
1177 CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
1181 CHECK(d0_dl_get_order(temp4, ctx->schnorr_G));
1182 CHECK(d0_iobuf_read_bignum(in, temp0)); // e == H(m || g^r)
1183 CHECK(d0_iobuf_read_bignum(in, temp1)); // x == (r - s*e) mod |G|
1185 CHECK(d0_iobuf_read_packet(in, msg, msglen));
1187 // VERIFY: g^x * (g^s)^-e = g^(x - s*e) = g^r
1189 // verify schnorr ID scheme
1190 // we need g^r = g^x (g^s)^e
1191 CHECK(d0_bignum_mod_pow(temp2, four, temp1, ctx->schnorr_G));
1192 #ifdef D0_BLIND_ID_POSITIVE_PROTOCOL
1193 CHECK(d0_bignum_mod_inv(temp3, ctx->schnorr_g_to_s, ctx->schnorr_G));
1194 CHECK(d0_bignum_mod_pow(temp1, temp3, temp0, ctx->schnorr_G));
1196 CHECK(d0_bignum_mod_pow(temp1, ctx->schnorr_g_to_s, temp0, ctx->schnorr_G));
1198 CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G)); // temp3 now is g^r
1200 // hash it, hash it, everybody hash it
1201 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
1202 CHECK(d0_iobuf_write_packet(conv, msg, *msglen));
1203 CHECK(d0_iobuf_write_bignum(conv, temp3));
1204 d0_iobuf_close(conv, &sz);
1206 CHECK(d0_longhash_destructive(convbuf, sz, shabuf, (d0_bignum_size(temp4) + 7) / 8));
1207 CHECK(d0_bignum_import_unsigned(temp1, shabuf, (d0_bignum_size(temp4) + 7) / 8));
1210 CHECK(!d0_bignum_cmp(temp0, temp1));
1213 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
1215 d0_iobuf_close(in, NULL);
1219 d0_iobuf_close(in, NULL);
1222 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)
1224 return d0_blind_id_sign_with_private_id_verify_internal(ctx, is_first, recv_modulus, 1, inbuf, inbuflen, msg, msglen, status);
1226 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)
1228 return d0_blind_id_sign_with_private_id_verify_internal(ctx, is_first, recv_modulus, 0, inbuf, inbuflen, (char *) msg, &msglen, status);
1231 D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
1233 d0_iobuf_t *out = NULL;
1234 static unsigned char convbuf[1024];
1235 d0_iobuf_t *conv = NULL;
1240 USING(schnorr_g_to_s);
1242 out = d0_iobuf_open_write(outbuf, *outbuflen);
1243 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
1245 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
1246 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
1247 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_g_to_s));
1248 CHECK(d0_iobuf_close(conv, &sz));
1251 n = (*outbuflen / 4) * 3;
1252 if(n > SHA_DIGESTSIZE)
1254 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
1255 CHECK(d0_iobuf_conv_base64_out(out));
1257 return d0_iobuf_close(out, outbuflen);
1261 d0_iobuf_close(conv, &sz);
1262 d0_iobuf_close(out, outbuflen);
1266 D0_BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
1268 USING(t); USING(other_g_to_t); USING(schnorr_G);
1270 // temps: temp0 result
1271 CHECK(d0_bignum_mod_pow(temp0, ctx->other_g_to_t, ctx->t, ctx->schnorr_G));
1272 return d0_longhash_bignum(temp0, (unsigned char *) outbuf, *outbuflen);
1278 d0_blind_id_t *d0_blind_id_new(void)
1280 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
1281 memset(b, 0, sizeof(*b));
1285 void d0_blind_id_free(d0_blind_id_t *a)
1287 d0_blind_id_clear(a);
1291 void d0_blind_id_util_sha256(char *out, const char *in, size_t n)
1294 SHA256_Init(&context);
1295 SHA256_Update(&context, (const unsigned char *) in, n);
1296 return SHA256_Final((unsigned char *) out, &context);