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"
27 // for zero knowledge, we need multiple instances of schnorr ID scheme... should normally be sequential
28 // parallel schnorr ID is not provably zero knowledge :(
29 // (evil verifier can know all questions in advance, so sequential is disadvantage for him)
30 // we'll just live with a 1:1048576 chance of cheating, and support reauthenticating
32 #define SCHNORR_BITS 20
33 // probability of cheat: 2^(-bits+1)
35 #define SCHNORR_HASHSIZE 3
36 // cannot be >= SHA_DIGEST_LENGTH
37 // *8 must be >= SCHNORR_BITS
39 #define MSGSIZE 640 // ought to be enough for anyone
43 // signing (Xonotic pub and priv key)
44 d0_bignum_t *rsa_n, *rsa_e, *rsa_d;
46 // public data (Schnorr ID)
47 d0_bignum_t *schnorr_G;
49 // private data (player ID private key)
50 d0_bignum_t *schnorr_s;
52 // public data (player ID public key, this is what the server gets to know)
53 d0_bignum_t *schnorr_4_to_s;
54 d0_bignum_t *schnorr_H_4_to_s_signature; // 0 when signature is invalid
55 // as hash function H, we get the SHA1 and reinterpret as bignum - yes, it always is < 160 bits
58 d0_bignum_t *rsa_blind_signature_camouflage; // random number blind signature
60 d0_bignum_t *r; // random number for schnorr ID
61 d0_bignum_t *other_4_to_r; // for DH key exchange
62 d0_bignum_t *challenge; // challenge
64 char msghash[SCHNORR_HASHSIZE]; // init hash
65 char msg[MSGSIZE]; // message
66 size_t msglen; // message length
69 #define CHECK(x) do { if(!(x)) goto fail; } while(0)
70 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
72 #define USING(x) if(!(ctx->x)) return 0
75 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
77 void d0_blind_id_INITIALIZE(void)
79 d0_bignum_INITIALIZE();
80 CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
81 CHECK_ASSIGN(one, d0_bignum_int(one, 1));
82 CHECK_ASSIGN(four, d0_bignum_int(four, 4));
83 CHECK_ASSIGN(temp0, d0_bignum_int(temp0, 0));
84 CHECK_ASSIGN(temp1, d0_bignum_int(temp1, 0));
85 CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
86 CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
87 CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
92 void d0_blind_id_SHUTDOWN(void)
97 d0_bignum_free(temp0);
98 d0_bignum_free(temp1);
99 d0_bignum_free(temp2);
100 d0_bignum_free(temp3);
101 d0_bignum_free(temp4);
102 d0_bignum_SHUTDOWN();
106 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
108 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
109 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
115 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
117 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
118 CHECK(d0_bignum_add(G, G, one));
124 BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
131 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
132 if(d0_bignum_isprime(temp0, 0) == 0)
134 CHECK(d0_dl_get_from_order(G, temp0));
135 if(d0_bignum_isprime(G, 10) == 0)
137 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
146 BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
148 // uses temp0 to temp4
151 int pb = (size + 1)/2;
159 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
160 if(d0_bignum_isprime(temp0, 10) == 0)
162 CHECK(d0_bignum_sub(temp2, temp0, one));
163 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
164 if(!d0_bignum_cmp(temp4, one))
173 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
174 if(!d0_bignum_cmp(temp1, temp0))
180 if(d0_bignum_isprime(temp1, 10) == 0)
182 CHECK(d0_bignum_sub(temp3, temp1, one));
183 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
184 if(!d0_bignum_cmp(temp4, one))
192 CHECK(d0_bignum_mul(n, temp0, temp1));
194 // d = challenge^-1 mod (temp0-1)(temp1-1)
195 CHECK(d0_bignum_mul(temp0, temp2, temp3));
196 CHECK(d0_bignum_mod_inv(d, challenge, temp0));
202 BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
204 // uses temp0 to temp4
207 int pb = (size + 1)/2;
215 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
216 if(d0_bignum_isprime(temp0, 10) == 0)
218 CHECK(d0_bignum_sub(temp2, temp0, one));
219 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
220 if(!d0_bignum_cmp(temp4, one))
229 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
230 if(!d0_bignum_cmp(temp1, temp0))
238 CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
239 if(reject(ctx, pass))
242 if(d0_bignum_isprime(temp1, 10) == 0)
244 CHECK(d0_bignum_sub(temp3, temp1, one));
245 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
246 if(!d0_bignum_cmp(temp4, one))
253 // ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
254 CHECK(d0_bignum_mul(temp0, temp2, temp3));
255 CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
261 WARN_UNUSED_RESULT BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t *outbuflen)
263 d0_iobuf_t *out = NULL;
264 static unsigned char convbuf[1024];
265 d0_iobuf_t *conv = NULL;
269 while(n > SHA_DIGESTSIZE)
271 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
272 CHECK(d0_iobuf_write_bignum(conv, temp0));
273 CHECK(d0_iobuf_close(conv, &sz));
275 memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
276 outbuf += SHA_DIGESTSIZE;
278 CHECK(d0_bignum_add(temp0, temp0, one));
280 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
281 CHECK(d0_iobuf_write_bignum(conv, temp0));
282 CHECK(d0_iobuf_close(conv, &sz));
284 memcpy(outbuf, sha(convbuf, sz), n);
286 return d0_iobuf_close(out, outbuflen);
290 d0_iobuf_close(conv, &sz);
294 void d0_blind_id_clear(d0_blind_id_t *ctx)
296 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
297 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
298 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
299 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
300 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
301 if(ctx->schnorr_4_to_s) d0_bignum_free(ctx->schnorr_4_to_s);
302 if(ctx->schnorr_H_4_to_s_signature) d0_bignum_free(ctx->schnorr_H_4_to_s_signature);
303 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
304 if(ctx->r) d0_bignum_free(ctx->r);
305 if(ctx->challenge) d0_bignum_free(ctx->challenge);
306 if(ctx->other_4_to_r) d0_bignum_free(ctx->other_4_to_r);
307 memset(ctx, 0, sizeof(*ctx));
310 WARN_UNUSED_RESULT BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
312 d0_blind_id_clear(ctx);
313 if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
314 if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
315 if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
316 if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
317 if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
318 if(src->schnorr_4_to_s) CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mov(NULL, src->schnorr_4_to_s));
319 if(src->schnorr_H_4_to_s_signature) CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_bignum_mov(NULL, src->schnorr_H_4_to_s_signature));
320 if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
321 if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
322 if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
323 if(src->other_4_to_r) CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mov(NULL, src->other_4_to_r));
324 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
325 ctx->msglen = src->msglen;
326 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
329 d0_blind_id_clear(ctx);
333 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key_fastreject(d0_blind_id_t *ctx, int k, d0_fastreject_function reject, void *pass)
335 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
337 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
338 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
339 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
341 CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
343 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
349 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
351 return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
354 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
356 d0_iobuf_t *in = NULL;
358 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
360 in = d0_iobuf_open_read(inbuf, inbuflen);
362 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
363 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
364 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
365 return d0_iobuf_close(in, NULL);
368 d0_iobuf_close(in, NULL);
372 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
374 d0_iobuf_t *in = NULL;
376 REPLACING(rsa_n); REPLACING(rsa_e);
378 in = d0_iobuf_open_read(inbuf, inbuflen);
379 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
380 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
381 return d0_iobuf_close(in, NULL);
384 d0_iobuf_close(in, NULL);
388 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
390 d0_iobuf_t *out = NULL;
392 USING(rsa_n); USING(rsa_e); USING(rsa_d);
394 out = d0_iobuf_open_write(outbuf, *outbuflen);
395 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
396 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
397 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
398 return d0_iobuf_close(out, outbuflen);
401 d0_iobuf_close(out, outbuflen);
405 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
407 d0_iobuf_t *out = NULL;
409 USING(rsa_n); USING(rsa_e);
411 out = d0_iobuf_open_write(outbuf, *outbuflen);
412 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
413 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
414 return d0_iobuf_close(out, outbuflen);
417 if(!d0_iobuf_close(out, outbuflen))
422 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
424 d0_iobuf_t *out = NULL;
425 static unsigned char convbuf[2048];
426 d0_iobuf_t *conv = NULL;
429 USING(rsa_n); USING(rsa_e);
431 out = d0_iobuf_open_write(outbuf, *outbuflen);
432 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
434 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
435 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
436 CHECK(d0_iobuf_close(conv, &sz));
439 n = (*outbuflen / 4) * 3;
440 if(n > SHA_DIGESTSIZE)
442 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
443 CHECK(d0_iobuf_conv_base64_out(out));
445 return d0_iobuf_close(out, outbuflen);
449 d0_iobuf_close(conv, &sz);
450 d0_iobuf_close(out, outbuflen);
454 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
457 REPLACING(schnorr_G);
459 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
460 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
466 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
468 d0_iobuf_t *in = NULL;
470 REPLACING(schnorr_G);
472 in = d0_iobuf_open_read(inbuf, inbuflen);
473 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
474 return d0_iobuf_close(in, NULL);
477 d0_iobuf_close(in, NULL);
481 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
483 d0_iobuf_t *out = NULL;
487 out = d0_iobuf_open_write(outbuf, *outbuflen);
488 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
489 return d0_iobuf_close(out, outbuflen);
492 d0_iobuf_close(out, outbuflen);
496 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
498 // temps: temp0 = order
500 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s);
502 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
503 CHECK(d0_bignum_shl(temp1, ctx->schnorr_G, -1));
504 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
505 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mod_pow(ctx->schnorr_4_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
506 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_bignum_zero(ctx->schnorr_H_4_to_s_signature));
513 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
515 d0_iobuf_t *out = NULL;
516 static unsigned char convbuf[2048];
519 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
520 USING(rsa_n); USING(rsa_e); USING(schnorr_4_to_s);
521 REPLACING(rsa_blind_signature_camouflage);
523 out = d0_iobuf_open_write(outbuf, *outbuflen);
525 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
526 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
527 // we will actually sign SHA(4^s) to prevent a malleability attack!
528 sz = (d0_bignum_size(ctx->schnorr_4_to_s) + 7) / 8;
529 CHECK(d0_bignum_export_unsigned(ctx->schnorr_4_to_s, convbuf, sz) >= 0);
530 CHECK(d0_bignum_import_unsigned(temp2, sha(convbuf, sz), SHA_DIGESTSIZE));
532 CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
533 CHECK(d0_iobuf_write_bignum(out, temp1));
534 return d0_iobuf_close(out, outbuflen);
537 d0_iobuf_close(out, outbuflen);
541 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)
543 d0_iobuf_t *in = NULL;
544 d0_iobuf_t *out = NULL;
546 // temps: temp0 input, temp1 temp0^d
547 USING(rsa_d); USING(rsa_n);
549 in = d0_iobuf_open_read(inbuf, inbuflen);
550 out = d0_iobuf_open_write(outbuf, *outbuflen);
552 CHECK(d0_iobuf_read_bignum(in, temp0));
553 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
554 CHECK(d0_iobuf_write_bignum(out, temp1));
556 d0_iobuf_close(in, NULL);
557 return d0_iobuf_close(out, outbuflen);
560 d0_iobuf_close(in, NULL);
561 d0_iobuf_close(out, outbuflen);
565 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
567 d0_iobuf_t *in = NULL;
569 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
570 USING(rsa_blind_signature_camouflage); USING(rsa_n);
571 REPLACING(schnorr_H_4_to_s_signature);
573 in = d0_iobuf_open_read(inbuf, inbuflen);
575 CHECK(d0_iobuf_read_bignum(in, temp0));
576 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
577 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_H_4_to_s_signature, temp0, temp1, ctx->rsa_n));
579 return d0_iobuf_close(in, NULL);
582 d0_iobuf_close(in, NULL);
586 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
588 d0_iobuf_t *in = NULL;
590 REPLACING(rsa_blind_signature_camouflage);
592 in = d0_iobuf_open_read(inbuf, inbuflen);
594 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
596 return d0_iobuf_close(in, NULL);
599 d0_iobuf_close(in, NULL);
603 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_request_camouflage(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
605 d0_iobuf_t *out = NULL;
607 USING(rsa_blind_signature_camouflage);
609 out = d0_iobuf_open_write(outbuf, *outbuflen);
611 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
613 return d0_iobuf_close(out, outbuflen);
616 d0_iobuf_close(out, outbuflen);
620 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
622 d0_iobuf_t *in = NULL;
624 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_4_to_s_signature);
626 in = d0_iobuf_open_read(inbuf, inbuflen);
628 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
629 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
630 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_4_to_s_signature));
632 return d0_iobuf_close(in, NULL);
635 d0_iobuf_close(in, NULL);
639 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
641 d0_iobuf_t *in = NULL;
643 REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_4_to_s_signature);
645 in = d0_iobuf_open_read(inbuf, inbuflen);
647 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
648 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_4_to_s_signature));
650 return d0_iobuf_close(in, NULL);
653 d0_iobuf_close(in, NULL);
657 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
659 d0_iobuf_t *out = NULL;
661 USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_H_4_to_s_signature);
663 out = d0_iobuf_open_write(outbuf, *outbuflen);
665 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
666 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
667 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_4_to_s_signature));
669 return d0_iobuf_close(out, outbuflen);
672 d0_iobuf_close(out, outbuflen);
676 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
678 d0_iobuf_t *out = NULL;
680 USING(schnorr_4_to_s); USING(schnorr_H_4_to_s_signature);
682 out = d0_iobuf_open_write(outbuf, *outbuflen);
684 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
685 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_4_to_s_signature));
687 return d0_iobuf_close(out, outbuflen);
690 d0_iobuf_close(out, outbuflen);
694 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)
696 // first run: send 4^s, 4^s signature
697 // 1. get random r, send HASH(4^r)
699 d0_iobuf_t *out = NULL;
700 static unsigned char convbuf[1024];
701 d0_iobuf_t *conv = NULL;
704 // temps: temp0 order, temp0 4^r
707 USING(schnorr_4_to_s); USING(schnorr_H_4_to_s_signature);
712 out = d0_iobuf_open_write(outbuf, *outbuflen);
718 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
719 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
720 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_4_to_s_signature));
723 // start schnorr ID scheme
724 // generate random number r; x = g^r; send hash of x, remember r, forget x
725 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
726 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
727 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
729 // hash it, hash it, everybody hash it
730 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
731 CHECK(d0_iobuf_write_bignum(conv, temp0));
732 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
733 CHECK(d0_iobuf_write_bignum(conv, temp0));
734 d0_iobuf_close(conv, &sz);
736 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
737 CHECK(d0_iobuf_write_packet(out, msg, msglen));
739 return d0_iobuf_close(out, outbuflen);
742 d0_iobuf_close(out, outbuflen);
746 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)
747 // first run: get 4^s, 4^s signature
750 // 3. send challenge challenge of SCHNORR_BITS
752 d0_iobuf_t *in = NULL;
753 d0_iobuf_t *out = NULL;
754 static unsigned char convbuf[2048];
757 // temps: temp0 order, temp0 signature check
760 REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_4_to_s_signature);
762 REPLACING(schnorr_G);
768 USING(schnorr_4_to_s); USING(schnorr_H_4_to_s_signature);
771 USING(rsa_e); USING(rsa_n);
772 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r);
774 in = d0_iobuf_open_read(inbuf, inbuflen);
775 out = d0_iobuf_open_write(outbuf, *outbuflen);
781 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
782 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
783 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
785 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
786 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, zero) >= 0);
787 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, ctx->schnorr_G) < 0);
788 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_4_to_s_signature));
789 CHECK(d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, zero) >= 0);
790 CHECK(d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, ctx->rsa_n) < 0);
792 // check signature of key (t = k^d, so, t^challenge = k)
793 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_4_to_s_signature, ctx->rsa_e, ctx->rsa_n));
794 // we will actually sign SHA(4^s) to prevent a malleability attack!
795 sz = (d0_bignum_size(ctx->schnorr_4_to_s) + 7) / 8;
796 CHECK(d0_bignum_export_unsigned(ctx->schnorr_4_to_s, convbuf, sz) >= 0);
797 CHECK(d0_bignum_import_unsigned(temp2, sha(convbuf, sz), SHA_DIGESTSIZE));
798 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
800 if(d0_bignum_cmp(temp0, temp1))
802 // accept the key anyway, but mark as failed signature! will later return 0 in status
803 CHECK(d0_bignum_zero(ctx->schnorr_H_4_to_s_signature));
807 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
808 ctx->msglen = MSGSIZE;
809 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
812 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
814 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
817 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
818 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
819 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
820 CHECK(d0_iobuf_write_bignum(out, temp0));
823 *status = !!d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, zero);
825 d0_iobuf_close(in, NULL);
826 return d0_iobuf_close(out, outbuflen);
829 d0_iobuf_close(in, NULL);
830 d0_iobuf_close(out, outbuflen);
834 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)
835 // 1. read challenge challenge of SCHNORR_BITS
836 // 2. reply with r + s * challenge mod order
838 d0_iobuf_t *in = NULL;
839 d0_iobuf_t *out = NULL;
841 // temps: 0 order, 1 prod, 2 y, 3 challenge
842 REPLACING(other_4_to_r);
843 USING(schnorr_G); USING(schnorr_s); USING(r);
845 in = d0_iobuf_open_read(inbuf, inbuflen);
846 out = d0_iobuf_open_write(outbuf, *outbuflen);
848 CHECK(d0_iobuf_read_bignum(in, temp3));
849 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
850 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
853 CHECK_ASSIGN(ctx->other_4_to_r, d0_iobuf_read_bignum(in, ctx->other_4_to_r));
854 CHECK(d0_bignum_cmp(ctx->other_4_to_r, zero) > 0);
855 CHECK(d0_bignum_cmp(ctx->other_4_to_r, ctx->schnorr_G) < 0);
857 // send response for schnorr ID scheme
858 // i.challenge. r + ctx->schnorr_s * temp3
859 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
860 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
861 CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
862 CHECK(d0_iobuf_write_bignum(out, temp2));
864 d0_iobuf_close(in, NULL);
865 return d0_iobuf_close(out, outbuflen);
868 d0_iobuf_close(in, NULL);
869 d0_iobuf_close(out, outbuflen);
873 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)
874 // 1. read y = r + s * challenge mod order
875 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
876 // (check using H(g^r) which we know)
878 d0_iobuf_t *in = NULL;
879 static unsigned char convbuf[1024];
880 d0_iobuf_t *conv = NULL;
883 // temps: 0 y 1 order
884 USING(challenge); USING(schnorr_G);
885 REPLACING(other_4_to_r);
887 in = d0_iobuf_open_read(inbuf, inbuflen);
889 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
890 CHECK(d0_iobuf_read_bignum(in, temp0));
891 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
892 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
894 // verify schnorr ID scheme
895 // we need 4^temp0 (g^s)^-challenge
896 CHECK(d0_bignum_neg(temp1, ctx->challenge));
897 CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_4_to_s, temp1, ctx->schnorr_G));
898 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
899 CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mod_mul(ctx->other_4_to_r, temp1, temp2, ctx->schnorr_G));
900 // hash must be equal to msghash
902 // hash it, hash it, everybody hash it
903 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
904 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
905 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
906 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
907 d0_iobuf_close(conv, &sz);
909 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
911 // FAIL (not owned by player)
916 *status = !!d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, zero);
918 if(ctx->msglen <= *msglen)
919 memcpy(msg, ctx->msg, ctx->msglen);
921 memcpy(msg, ctx->msg, *msglen);
922 *msglen = ctx->msglen;
924 d0_iobuf_close(in, NULL);
928 d0_iobuf_close(in, NULL);
932 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
934 d0_iobuf_t *out = NULL;
935 static unsigned char convbuf[1024];
936 d0_iobuf_t *conv = NULL;
939 USING(schnorr_4_to_s);
941 out = d0_iobuf_open_write(outbuf, *outbuflen);
942 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
944 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_4_to_s));
945 CHECK(d0_iobuf_close(conv, &sz));
948 n = (*outbuflen / 4) * 3;
949 if(n > SHA_DIGESTSIZE)
951 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
952 CHECK(d0_iobuf_conv_base64_out(out));
954 return d0_iobuf_close(out, outbuflen);
958 d0_iobuf_close(conv, &sz);
959 d0_iobuf_close(out, outbuflen);
963 BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
965 USING(r); USING(other_4_to_r); USING(schnorr_G);
967 // temps: temp0 result
968 CHECK(d0_bignum_mod_pow(temp0, ctx->other_4_to_r, ctx->r, ctx->schnorr_G));
969 return d0_longhash_destructive(temp0, outbuf, outbuflen);
975 d0_blind_id_t *d0_blind_id_new(void)
977 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
978 memset(b, 0, sizeof(*b));
982 void d0_blind_id_free(d0_blind_id_t *a)
984 d0_blind_id_clear(a);