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)
84 #define USING(x) if(!(ctx->x)) return 0
87 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
89 void d0_blind_id_INITIALIZE(void)
91 d0_bignum_INITIALIZE();
92 CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
93 CHECK_ASSIGN(one, d0_bignum_int(one, 1));
94 CHECK_ASSIGN(four, d0_bignum_int(four, 4));
95 CHECK_ASSIGN(temp0, d0_bignum_int(temp0, 0));
96 CHECK_ASSIGN(temp1, d0_bignum_int(temp1, 0));
97 CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
98 CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
99 CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
104 void d0_blind_id_SHUTDOWN(void)
106 d0_bignum_free(zero);
108 d0_bignum_free(four);
109 d0_bignum_free(temp0);
110 d0_bignum_free(temp1);
111 d0_bignum_free(temp2);
112 d0_bignum_free(temp3);
113 d0_bignum_free(temp4);
114 d0_bignum_SHUTDOWN();
118 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
120 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
121 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
127 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
129 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
130 CHECK(d0_bignum_add(G, G, one));
136 BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
143 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
144 if(d0_bignum_isprime(temp0, 0) == 0)
146 CHECK(d0_dl_get_from_order(G, temp0));
147 if(d0_bignum_isprime(G, 10) == 0)
149 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
158 BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
160 // uses temp0 to temp4
163 int pb = (size + 1)/2;
171 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
172 if(d0_bignum_isprime(temp0, 10) == 0)
174 CHECK(d0_bignum_sub(temp2, temp0, one));
175 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
176 if(!d0_bignum_cmp(temp4, one))
185 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
186 if(!d0_bignum_cmp(temp1, temp0))
192 if(d0_bignum_isprime(temp1, 10) == 0)
194 CHECK(d0_bignum_sub(temp3, temp1, one));
195 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
196 if(!d0_bignum_cmp(temp4, one))
204 CHECK(d0_bignum_mul(n, temp0, temp1));
206 // d = challenge^-1 mod (temp0-1)(temp1-1)
207 CHECK(d0_bignum_mul(temp0, temp2, temp3));
208 CHECK(d0_bignum_mod_inv(d, challenge, temp0));
214 BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
216 // uses temp0 to temp4
219 int pb = (size + 1)/2;
227 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
228 if(d0_bignum_isprime(temp0, 10) == 0)
230 CHECK(d0_bignum_sub(temp2, temp0, one));
231 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
232 if(!d0_bignum_cmp(temp4, one))
241 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
242 if(!d0_bignum_cmp(temp1, temp0))
250 CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
251 if(reject(ctx, pass))
254 if(d0_bignum_isprime(temp1, 10) == 0)
256 CHECK(d0_bignum_sub(temp3, temp1, one));
257 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
258 if(!d0_bignum_cmp(temp4, one))
265 // ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
266 CHECK(d0_bignum_mul(temp0, temp2, temp3));
267 CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
273 WARN_UNUSED_RESULT BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t outbuflen)
275 d0_iobuf_t *out = NULL;
276 static unsigned char convbuf[1024];
280 while(n > SHA_DIGESTSIZE)
282 sz = (d0_bignum_size(clobberme) + 7) / 8;
283 CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
284 memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
285 outbuf += SHA_DIGESTSIZE;
287 CHECK(d0_bignum_add(clobberme, clobberme, one));
289 sz = (d0_bignum_size(clobberme) + 7) / 8;
290 CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
291 memcpy(outbuf, sha(convbuf, sz), n);
298 void d0_blind_id_clear(d0_blind_id_t *ctx)
300 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
301 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
302 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
303 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
304 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
305 if(ctx->schnorr_g_to_s) d0_bignum_free(ctx->schnorr_g_to_s);
306 if(ctx->schnorr_H_g_to_s_signature) d0_bignum_free(ctx->schnorr_H_g_to_s_signature);
307 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
308 if(ctx->r) d0_bignum_free(ctx->r);
309 if(ctx->challenge) d0_bignum_free(ctx->challenge);
310 if(ctx->t) d0_bignum_free(ctx->t);
311 if(ctx->g_to_t) d0_bignum_free(ctx->g_to_t);
312 if(ctx->other_g_to_t) d0_bignum_free(ctx->other_g_to_t);
313 memset(ctx, 0, sizeof(*ctx));
316 WARN_UNUSED_RESULT BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
318 d0_blind_id_clear(ctx);
319 if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
320 if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
321 if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
322 if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
323 if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
324 if(src->schnorr_g_to_s) CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mov(NULL, src->schnorr_g_to_s));
325 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));
326 if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
327 if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
328 if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
329 if(src->t) CHECK_ASSIGN(ctx->t, d0_bignum_mov(NULL, src->t));
330 if(src->g_to_t) CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mov(NULL, src->g_to_t));
331 if(src->other_g_to_t) CHECK_ASSIGN(ctx->other_g_to_t, d0_bignum_mov(NULL, src->other_g_to_t));
332 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
333 ctx->msglen = src->msglen;
334 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
337 d0_blind_id_clear(ctx);
341 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key_fastreject(d0_blind_id_t *ctx, int k, d0_fastreject_function reject, void *pass)
343 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
345 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
346 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
347 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
349 CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
351 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
357 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
359 return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
362 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
364 d0_iobuf_t *in = NULL;
366 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
368 in = d0_iobuf_open_read(inbuf, inbuflen);
370 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
371 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
372 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
373 return d0_iobuf_close(in, NULL);
376 d0_iobuf_close(in, NULL);
380 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
382 d0_iobuf_t *in = NULL;
384 REPLACING(rsa_n); REPLACING(rsa_e);
386 in = d0_iobuf_open_read(inbuf, inbuflen);
387 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
388 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
389 return d0_iobuf_close(in, NULL);
392 d0_iobuf_close(in, NULL);
396 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
398 d0_iobuf_t *out = NULL;
400 USING(rsa_n); USING(rsa_e); USING(rsa_d);
402 out = d0_iobuf_open_write(outbuf, *outbuflen);
403 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
404 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
405 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
406 return d0_iobuf_close(out, outbuflen);
409 d0_iobuf_close(out, outbuflen);
413 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
415 d0_iobuf_t *out = NULL;
417 USING(rsa_n); USING(rsa_e);
419 out = d0_iobuf_open_write(outbuf, *outbuflen);
420 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
421 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
422 return d0_iobuf_close(out, outbuflen);
425 if(!d0_iobuf_close(out, outbuflen))
430 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
432 d0_iobuf_t *out = NULL;
433 static unsigned char convbuf[2048];
434 d0_iobuf_t *conv = NULL;
437 USING(rsa_n); USING(rsa_e);
439 out = d0_iobuf_open_write(outbuf, *outbuflen);
440 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
442 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
443 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
444 CHECK(d0_iobuf_close(conv, &sz));
447 n = (*outbuflen / 4) * 3;
448 if(n > SHA_DIGESTSIZE)
450 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
451 CHECK(d0_iobuf_conv_base64_out(out));
453 return d0_iobuf_close(out, outbuflen);
457 d0_iobuf_close(conv, &sz);
458 d0_iobuf_close(out, outbuflen);
462 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
465 REPLACING(schnorr_G);
467 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
468 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
474 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
476 d0_iobuf_t *in = NULL;
478 REPLACING(schnorr_G);
480 in = d0_iobuf_open_read(inbuf, inbuflen);
481 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
482 return d0_iobuf_close(in, NULL);
485 d0_iobuf_close(in, NULL);
489 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
491 d0_iobuf_t *out = NULL;
495 out = d0_iobuf_open_write(outbuf, *outbuflen);
496 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
497 return d0_iobuf_close(out, outbuflen);
500 d0_iobuf_close(out, outbuflen);
504 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
506 // temps: temp0 = order
508 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s);
510 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
511 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
512 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mod_pow(ctx->schnorr_g_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
513 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
520 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
522 d0_iobuf_t *out = NULL;
523 static unsigned char convbuf[2048], shabuf[2048];
526 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
527 USING(rsa_n); USING(rsa_e); USING(schnorr_g_to_s);
528 REPLACING(rsa_blind_signature_camouflage);
530 out = d0_iobuf_open_write(outbuf, *outbuflen);
532 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
533 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
535 // we will actually sign HA(4^s) to prevent a malleability attack!
536 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
537 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
538 if(sz > sizeof(shabuf))
540 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
541 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
544 CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
545 CHECK(d0_iobuf_write_bignum(out, temp1));
546 return d0_iobuf_close(out, outbuflen);
549 d0_iobuf_close(out, outbuflen);
553 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)
555 d0_iobuf_t *in = NULL;
556 d0_iobuf_t *out = NULL;
558 // temps: temp0 input, temp1 temp0^d
559 USING(rsa_d); USING(rsa_n);
561 in = d0_iobuf_open_read(inbuf, inbuflen);
562 out = d0_iobuf_open_write(outbuf, *outbuflen);
564 CHECK(d0_iobuf_read_bignum(in, temp0));
565 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
566 CHECK(d0_iobuf_write_bignum(out, temp1));
568 d0_iobuf_close(in, NULL);
569 return d0_iobuf_close(out, outbuflen);
572 d0_iobuf_close(in, NULL);
573 d0_iobuf_close(out, outbuflen);
577 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
579 d0_iobuf_t *in = NULL;
581 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
582 USING(rsa_blind_signature_camouflage); USING(rsa_n);
583 REPLACING(schnorr_H_g_to_s_signature);
585 in = d0_iobuf_open_read(inbuf, inbuflen);
587 CHECK(d0_iobuf_read_bignum(in, temp0));
588 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
589 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));
591 return d0_iobuf_close(in, NULL);
594 d0_iobuf_close(in, NULL);
598 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
600 d0_iobuf_t *in = NULL;
602 REPLACING(rsa_blind_signature_camouflage);
604 in = d0_iobuf_open_read(inbuf, inbuflen);
606 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
608 return d0_iobuf_close(in, NULL);
611 d0_iobuf_close(in, NULL);
615 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_request_camouflage(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
617 d0_iobuf_t *out = NULL;
619 USING(rsa_blind_signature_camouflage);
621 out = d0_iobuf_open_write(outbuf, *outbuflen);
623 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
625 return d0_iobuf_close(out, outbuflen);
628 d0_iobuf_close(out, outbuflen);
632 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
634 d0_iobuf_t *in = NULL;
636 REPLACING(schnorr_s); REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
638 in = d0_iobuf_open_read(inbuf, inbuflen);
640 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
641 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
642 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
644 return d0_iobuf_close(in, NULL);
647 d0_iobuf_close(in, NULL);
651 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
653 d0_iobuf_t *in = NULL;
655 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
657 in = d0_iobuf_open_read(inbuf, inbuflen);
659 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
660 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
662 return d0_iobuf_close(in, NULL);
665 d0_iobuf_close(in, NULL);
669 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
671 d0_iobuf_t *out = NULL;
673 USING(schnorr_s); USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
675 out = d0_iobuf_open_write(outbuf, *outbuflen);
677 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
678 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
679 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
681 return d0_iobuf_close(out, outbuflen);
684 d0_iobuf_close(out, outbuflen);
688 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
690 d0_iobuf_t *out = NULL;
692 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
694 out = d0_iobuf_open_write(outbuf, *outbuflen);
696 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
697 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
699 return d0_iobuf_close(out, outbuflen);
702 d0_iobuf_close(out, outbuflen);
706 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)
708 // first run: send 4^s, 4^s signature
709 // 1. get random r, send HASH(4^r)
711 d0_iobuf_t *out = NULL;
712 static unsigned char convbuf[1024];
713 d0_iobuf_t *conv = NULL;
716 // temps: temp0 order, temp0 4^r
719 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
722 REPLACING(r); REPLACING(t); REPLACING(g_to_t);
724 out = d0_iobuf_open_write(outbuf, *outbuflen);
730 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
731 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
732 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
735 // start schnorr ID scheme
736 // generate random number r; x = g^r; send hash of x, remember r, forget x
737 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
738 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
739 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
741 // initialize Signed Diffie Hellmann
742 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
743 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp1));
744 CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mod_pow(ctx->g_to_t, four, ctx->t, ctx->schnorr_G));
745 // can we SOMEHOW do this with just one mod_pow?
747 // hash it, hash it, everybody hash it
748 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
749 CHECK(d0_iobuf_write_bignum(conv, temp0));
750 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
751 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
752 CHECK(d0_iobuf_write_bignum(conv, temp0));
753 CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
754 d0_iobuf_close(conv, &sz);
756 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
757 CHECK(d0_iobuf_write_packet(out, msg, msglen));
759 return d0_iobuf_close(out, outbuflen);
762 d0_iobuf_close(out, outbuflen);
766 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)
767 // first run: get 4^s, 4^s signature
770 // 3. send challenge challenge of SCHNORR_BITS
772 d0_iobuf_t *in = NULL;
773 d0_iobuf_t *out = NULL;
774 static unsigned char shabuf[2048];
777 // temps: temp0 order, temp0 signature check
780 REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
782 REPLACING(schnorr_G);
788 USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
791 USING(rsa_e); USING(rsa_n);
792 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r); REPLACING(t);
794 in = d0_iobuf_open_read(inbuf, inbuflen);
795 out = d0_iobuf_open_write(outbuf, *outbuflen);
801 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
802 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
803 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
805 CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
806 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
807 CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
808 CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
809 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
810 CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
812 // check signature of key (t = k^d, so, t^challenge = k)
813 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
815 // we will actually sign SHA(4^s) to prevent a malleability attack!
816 CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
817 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
818 if(sz > sizeof(shabuf))
820 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
821 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
823 // + 7 / 8 is too large, so let's mod it
824 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
827 if(d0_bignum_cmp(temp0, temp1))
829 // accept the key anyway, but mark as failed signature! will later return 0 in status
830 CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
834 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
835 ctx->msglen = MSGSIZE;
836 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
839 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
840 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
842 // Diffie Hellmann send
843 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
844 CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
845 CHECK(d0_bignum_mod_pow(temp0, four, ctx->t, ctx->schnorr_G));
846 CHECK(d0_iobuf_write_bignum(out, temp0));
849 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
851 d0_iobuf_close(in, NULL);
852 return d0_iobuf_close(out, outbuflen);
855 d0_iobuf_close(in, NULL);
856 d0_iobuf_close(out, outbuflen);
860 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)
861 // 1. read challenge challenge of SCHNORR_BITS
862 // 2. reply with r + s * challenge mod order
864 d0_iobuf_t *in = NULL;
865 d0_iobuf_t *out = NULL;
867 // temps: 0 order, 1 prod, 2 y, 3 challenge
868 REPLACING(other_g_to_t); REPLACING(t);
869 USING(schnorr_G); USING(schnorr_s); USING(r); USING(g_to_t);
871 in = d0_iobuf_open_read(inbuf, inbuflen);
872 out = d0_iobuf_open_write(outbuf, *outbuflen);
874 CHECK(d0_iobuf_read_bignum(in, temp3));
875 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
876 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
878 // send response for schnorr ID scheme
879 // i.challenge. r + ctx->schnorr_s * temp3
880 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
881 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
882 CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
883 CHECK(d0_iobuf_write_bignum(out, temp2));
885 // Diffie Hellmann recv
886 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
887 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
888 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
889 // Diffie Hellmann send
890 CHECK(d0_iobuf_write_bignum(out, ctx->g_to_t));
892 d0_iobuf_close(in, NULL);
893 return d0_iobuf_close(out, outbuflen);
896 d0_iobuf_close(in, NULL);
897 d0_iobuf_close(out, outbuflen);
901 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)
902 // 1. read y = r + s * challenge mod order
903 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
904 // (check using H(g^r) which we know)
906 d0_iobuf_t *in = NULL;
907 static unsigned char convbuf[1024];
908 d0_iobuf_t *conv = NULL;
911 // temps: 0 y 1 order
912 USING(challenge); USING(schnorr_G);
913 REPLACING(other_g_to_t);
915 in = d0_iobuf_open_read(inbuf, inbuflen);
917 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
918 CHECK(d0_iobuf_read_bignum(in, temp0));
919 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
920 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
922 // verify schnorr ID scheme
923 // we need 4^r = 4^temp0 (g^s)^-challenge
924 CHECK(d0_bignum_mod_inv(temp1, ctx->schnorr_g_to_s, ctx->schnorr_G));
925 CHECK(d0_bignum_mod_pow(temp2, temp1, ctx->challenge, ctx->schnorr_G));
926 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
927 CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G));
929 // Diffie Hellmann recv
930 CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
931 CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
932 CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
934 // hash it, hash it, everybody hash it
935 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
936 CHECK(d0_iobuf_write_bignum(conv, temp3));
937 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
938 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
939 CHECK(d0_iobuf_write_bignum(conv, temp3));
940 CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
941 d0_iobuf_close(conv, &sz);
943 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
945 // FAIL (not owned by player)
950 *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
952 if(ctx->msglen <= *msglen)
953 memcpy(msg, ctx->msg, ctx->msglen);
955 memcpy(msg, ctx->msg, *msglen);
956 *msglen = ctx->msglen;
958 d0_iobuf_close(in, NULL);
962 d0_iobuf_close(in, NULL);
966 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
968 d0_iobuf_t *out = NULL;
969 static unsigned char convbuf[1024];
970 d0_iobuf_t *conv = NULL;
973 USING(schnorr_g_to_s);
975 out = d0_iobuf_open_write(outbuf, *outbuflen);
976 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
978 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_g_to_s));
979 CHECK(d0_iobuf_close(conv, &sz));
982 n = (*outbuflen / 4) * 3;
983 if(n > SHA_DIGESTSIZE)
985 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
986 CHECK(d0_iobuf_conv_base64_out(out));
988 return d0_iobuf_close(out, outbuflen);
992 d0_iobuf_close(conv, &sz);
993 d0_iobuf_close(out, outbuflen);
997 BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
999 USING(t); USING(other_g_to_t); USING(schnorr_G);
1001 // temps: temp0 result
1002 CHECK(d0_bignum_mod_pow(temp0, ctx->other_g_to_t, ctx->t, ctx->schnorr_G));
1003 return d0_longhash_destructive(temp0, outbuf, *outbuflen);
1009 d0_blind_id_t *d0_blind_id_new(void)
1011 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
1012 memset(b, 0, sizeof(*b));
1016 void d0_blind_id_free(d0_blind_id_t *a)
1018 d0_blind_id_clear(a);
1022 void d0_blind_id_util_sha256(char *out, const char *in, size_t n)
1025 SHA256_Init(&context);
1026 SHA256_Update(&context, (const unsigned char *) in, n);
1027 return SHA256_Final((unsigned char *) out, &context);