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 SHA_DIGESTSIZE
36 // cannot be >= SHA_DIGESTSIZE
37 // *8 must be >= SCHNORR_BITS
38 // no need to save bits here
40 #define MSGSIZE 640 // ought to be enough for anyone
44 // signing (Xonotic pub and priv key)
45 d0_bignum_t *rsa_n, *rsa_e, *rsa_d;
47 // public data (Schnorr ID)
48 d0_bignum_t *schnorr_G;
50 // private data (player ID private key)
51 d0_bignum_t *schnorr_s;
53 // public data (player ID public key, this is what the server gets to know)
54 d0_bignum_t *schnorr_4_to_s;
55 d0_bignum_t *schnorr_H_4_to_s_signature; // 0 when signature is invalid
56 // as hash function H, we get the SHA1 and reinterpret as bignum - yes, it always is < 160 bits
59 d0_bignum_t *rsa_blind_signature_camouflage; // random number blind signature
61 d0_bignum_t *r; // random number for schnorr ID
62 d0_bignum_t *other_4_to_r; // for DH key exchange
63 d0_bignum_t *challenge; // challenge
65 char msghash[SCHNORR_HASHSIZE]; // init hash
66 char msg[MSGSIZE]; // message
67 size_t msglen; // message length
70 #define CHECK(x) do { if(!(x)) goto fail; } while(0)
71 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
73 #define USING(x) if(!(ctx->x)) return 0
76 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
78 void d0_blind_id_INITIALIZE(void)
80 d0_bignum_INITIALIZE();
81 CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
82 CHECK_ASSIGN(one, d0_bignum_int(one, 1));
83 CHECK_ASSIGN(four, d0_bignum_int(four, 4));
84 CHECK_ASSIGN(temp0, d0_bignum_int(temp0, 0));
85 CHECK_ASSIGN(temp1, d0_bignum_int(temp1, 0));
86 CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
87 CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
88 CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
93 void d0_blind_id_SHUTDOWN(void)
98 d0_bignum_free(temp0);
99 d0_bignum_free(temp1);
100 d0_bignum_free(temp2);
101 d0_bignum_free(temp3);
102 d0_bignum_free(temp4);
103 d0_bignum_SHUTDOWN();
107 d0_bignum_t *d0_dl_get_order(d0_bignum_t *o, const d0_bignum_t *G)
109 CHECK_ASSIGN(o, d0_bignum_sub(o, G, one));
110 CHECK(d0_bignum_shl(o, o, -1)); // order o = (G-1)/2
116 d0_bignum_t *d0_dl_get_from_order(d0_bignum_t *G, const d0_bignum_t *o)
118 CHECK_ASSIGN(G, d0_bignum_shl(G, o, 1));
119 CHECK(d0_bignum_add(G, G, one));
125 BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
132 CHECK(d0_bignum_rand_bit_exact(temp0, size-1));
133 if(d0_bignum_isprime(temp0, 0) == 0)
135 CHECK(d0_dl_get_from_order(G, temp0));
136 if(d0_bignum_isprime(G, 10) == 0)
138 if(d0_bignum_isprime(temp0, 10) == 0) // finish the previous test
147 BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
149 // uses temp0 to temp4
152 int pb = (size + 1)/2;
160 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
161 if(d0_bignum_isprime(temp0, 10) == 0)
163 CHECK(d0_bignum_sub(temp2, temp0, one));
164 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
165 if(!d0_bignum_cmp(temp4, one))
174 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
175 if(!d0_bignum_cmp(temp1, temp0))
181 if(d0_bignum_isprime(temp1, 10) == 0)
183 CHECK(d0_bignum_sub(temp3, temp1, one));
184 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
185 if(!d0_bignum_cmp(temp4, one))
193 CHECK(d0_bignum_mul(n, temp0, temp1));
195 // d = challenge^-1 mod (temp0-1)(temp1-1)
196 CHECK(d0_bignum_mul(temp0, temp2, temp3));
197 CHECK(d0_bignum_mod_inv(d, challenge, temp0));
203 BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
205 // uses temp0 to temp4
208 int pb = (size + 1)/2;
216 CHECK(d0_bignum_rand_bit_exact(temp0, pb));
217 if(d0_bignum_isprime(temp0, 10) == 0)
219 CHECK(d0_bignum_sub(temp2, temp0, one));
220 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
221 if(!d0_bignum_cmp(temp4, one))
230 CHECK(d0_bignum_rand_bit_exact(temp1, qb));
231 if(!d0_bignum_cmp(temp1, temp0))
239 CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
240 if(reject(ctx, pass))
243 if(d0_bignum_isprime(temp1, 10) == 0)
245 CHECK(d0_bignum_sub(temp3, temp1, one));
246 CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
247 if(!d0_bignum_cmp(temp4, one))
254 // ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
255 CHECK(d0_bignum_mul(temp0, temp2, temp3));
256 CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
262 WARN_UNUSED_RESULT BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t outbuflen)
264 d0_iobuf_t *out = NULL;
265 static unsigned char convbuf[1024];
269 while(n > SHA_DIGESTSIZE)
271 sz = (d0_bignum_size(clobberme) + 7) / 8;
272 CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
273 memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
274 outbuf += SHA_DIGESTSIZE;
276 CHECK(d0_bignum_add(clobberme, clobberme, one));
278 sz = (d0_bignum_size(clobberme) + 7) / 8;
279 CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
280 memcpy(outbuf, sha(convbuf, sz), n);
287 void d0_blind_id_clear(d0_blind_id_t *ctx)
289 if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
290 if(ctx->rsa_e) d0_bignum_free(ctx->rsa_e);
291 if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
292 if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
293 if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
294 if(ctx->schnorr_4_to_s) d0_bignum_free(ctx->schnorr_4_to_s);
295 if(ctx->schnorr_H_4_to_s_signature) d0_bignum_free(ctx->schnorr_H_4_to_s_signature);
296 if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
297 if(ctx->r) d0_bignum_free(ctx->r);
298 if(ctx->challenge) d0_bignum_free(ctx->challenge);
299 if(ctx->other_4_to_r) d0_bignum_free(ctx->other_4_to_r);
300 memset(ctx, 0, sizeof(*ctx));
303 WARN_UNUSED_RESULT BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
305 d0_blind_id_clear(ctx);
306 if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
307 if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
308 if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
309 if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
310 if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
311 if(src->schnorr_4_to_s) CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mov(NULL, src->schnorr_4_to_s));
312 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));
313 if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
314 if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
315 if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
316 if(src->other_4_to_r) CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mov(NULL, src->other_4_to_r));
317 memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
318 ctx->msglen = src->msglen;
319 memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
322 d0_blind_id_clear(ctx);
326 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key_fastreject(d0_blind_id_t *ctx, int k, d0_fastreject_function reject, void *pass)
328 REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
330 CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
331 CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
332 CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
334 CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
336 CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
342 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
344 return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
347 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
349 d0_iobuf_t *in = NULL;
351 REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
353 in = d0_iobuf_open_read(inbuf, inbuflen);
355 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
356 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
357 CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
358 return d0_iobuf_close(in, NULL);
361 d0_iobuf_close(in, NULL);
365 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
367 d0_iobuf_t *in = NULL;
369 REPLACING(rsa_n); REPLACING(rsa_e);
371 in = d0_iobuf_open_read(inbuf, inbuflen);
372 CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
373 CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
374 return d0_iobuf_close(in, NULL);
377 d0_iobuf_close(in, NULL);
381 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
383 d0_iobuf_t *out = NULL;
385 USING(rsa_n); USING(rsa_e); USING(rsa_d);
387 out = d0_iobuf_open_write(outbuf, *outbuflen);
388 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
389 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
390 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
391 return d0_iobuf_close(out, outbuflen);
394 d0_iobuf_close(out, outbuflen);
398 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
400 d0_iobuf_t *out = NULL;
402 USING(rsa_n); USING(rsa_e);
404 out = d0_iobuf_open_write(outbuf, *outbuflen);
405 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
406 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
407 return d0_iobuf_close(out, outbuflen);
410 if(!d0_iobuf_close(out, outbuflen))
415 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
417 d0_iobuf_t *out = NULL;
418 static unsigned char convbuf[2048];
419 d0_iobuf_t *conv = NULL;
422 USING(rsa_n); USING(rsa_e);
424 out = d0_iobuf_open_write(outbuf, *outbuflen);
425 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
427 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
428 CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
429 CHECK(d0_iobuf_close(conv, &sz));
432 n = (*outbuflen / 4) * 3;
433 if(n > SHA_DIGESTSIZE)
435 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
436 CHECK(d0_iobuf_conv_base64_out(out));
438 return d0_iobuf_close(out, outbuflen);
442 d0_iobuf_close(conv, &sz);
443 d0_iobuf_close(out, outbuflen);
447 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
450 REPLACING(schnorr_G);
452 CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
453 CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
459 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
461 d0_iobuf_t *in = NULL;
463 REPLACING(schnorr_G);
465 in = d0_iobuf_open_read(inbuf, inbuflen);
466 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
467 return d0_iobuf_close(in, NULL);
470 d0_iobuf_close(in, NULL);
474 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
476 d0_iobuf_t *out = NULL;
480 out = d0_iobuf_open_write(outbuf, *outbuflen);
481 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
482 return d0_iobuf_close(out, outbuflen);
485 d0_iobuf_close(out, outbuflen);
489 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
491 // temps: temp0 = order
493 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s);
495 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
496 CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
497 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mod_pow(ctx->schnorr_4_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
498 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_bignum_zero(ctx->schnorr_H_4_to_s_signature));
505 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
507 d0_iobuf_t *out = NULL;
508 static unsigned char convbuf[2048], shabuf[2048];
511 // temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
512 USING(rsa_n); USING(rsa_e); USING(schnorr_4_to_s);
513 REPLACING(rsa_blind_signature_camouflage);
515 out = d0_iobuf_open_write(outbuf, *outbuflen);
517 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
518 CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
520 // we will actually sign HA(4^s) to prevent a malleability attack!
521 CHECK(d0_bignum_mov(temp2, ctx->schnorr_4_to_s));
522 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
523 if(sz > sizeof(shabuf))
525 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
526 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
529 CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
530 CHECK(d0_iobuf_write_bignum(out, temp1));
531 return d0_iobuf_close(out, outbuflen);
534 d0_iobuf_close(out, outbuflen);
538 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)
540 d0_iobuf_t *in = NULL;
541 d0_iobuf_t *out = NULL;
543 // temps: temp0 input, temp1 temp0^d
544 USING(rsa_d); USING(rsa_n);
546 in = d0_iobuf_open_read(inbuf, inbuflen);
547 out = d0_iobuf_open_write(outbuf, *outbuflen);
549 CHECK(d0_iobuf_read_bignum(in, temp0));
550 CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
551 CHECK(d0_iobuf_write_bignum(out, temp1));
553 d0_iobuf_close(in, NULL);
554 return d0_iobuf_close(out, outbuflen);
557 d0_iobuf_close(in, NULL);
558 d0_iobuf_close(out, outbuflen);
562 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
564 d0_iobuf_t *in = NULL;
566 // temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
567 USING(rsa_blind_signature_camouflage); USING(rsa_n);
568 REPLACING(schnorr_H_4_to_s_signature);
570 in = d0_iobuf_open_read(inbuf, inbuflen);
572 CHECK(d0_iobuf_read_bignum(in, temp0));
573 CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
574 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));
576 return d0_iobuf_close(in, NULL);
579 d0_iobuf_close(in, NULL);
583 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
585 d0_iobuf_t *in = NULL;
587 REPLACING(rsa_blind_signature_camouflage);
589 in = d0_iobuf_open_read(inbuf, inbuflen);
591 CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
593 return d0_iobuf_close(in, NULL);
596 d0_iobuf_close(in, NULL);
600 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_request_camouflage(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
602 d0_iobuf_t *out = NULL;
604 USING(rsa_blind_signature_camouflage);
606 out = d0_iobuf_open_write(outbuf, *outbuflen);
608 CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
610 return d0_iobuf_close(out, outbuflen);
613 d0_iobuf_close(out, outbuflen);
617 WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
619 d0_iobuf_t *in = NULL;
621 REPLACING(schnorr_s); REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_4_to_s_signature);
623 in = d0_iobuf_open_read(inbuf, inbuflen);
625 CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
626 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
627 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_4_to_s_signature));
629 return d0_iobuf_close(in, NULL);
632 d0_iobuf_close(in, NULL);
636 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
638 d0_iobuf_t *in = NULL;
640 REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_4_to_s_signature);
642 in = d0_iobuf_open_read(inbuf, inbuflen);
644 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
645 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_4_to_s_signature));
647 return d0_iobuf_close(in, NULL);
650 d0_iobuf_close(in, NULL);
654 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
656 d0_iobuf_t *out = NULL;
658 USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_H_4_to_s_signature);
660 out = d0_iobuf_open_write(outbuf, *outbuflen);
662 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
663 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
664 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_4_to_s_signature));
666 return d0_iobuf_close(out, outbuflen);
669 d0_iobuf_close(out, outbuflen);
673 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
675 d0_iobuf_t *out = NULL;
677 USING(schnorr_4_to_s); USING(schnorr_H_4_to_s_signature);
679 out = d0_iobuf_open_write(outbuf, *outbuflen);
681 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
682 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_4_to_s_signature));
684 return d0_iobuf_close(out, outbuflen);
687 d0_iobuf_close(out, outbuflen);
691 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)
693 // first run: send 4^s, 4^s signature
694 // 1. get random r, send HASH(4^r)
696 d0_iobuf_t *out = NULL;
697 static unsigned char convbuf[1024];
698 d0_iobuf_t *conv = NULL;
701 // temps: temp0 order, temp0 4^r
704 USING(schnorr_4_to_s); USING(schnorr_H_4_to_s_signature);
709 out = d0_iobuf_open_write(outbuf, *outbuflen);
715 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
716 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
717 CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_4_to_s_signature));
720 // start schnorr ID scheme
721 // generate random number r; x = g^r; send hash of x, remember r, forget x
722 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
723 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
724 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
726 // hash it, hash it, everybody hash it
727 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
728 CHECK(d0_iobuf_write_bignum(conv, temp0));
729 CHECK(d0_iobuf_write_packet(conv, msg, msglen));
730 CHECK(d0_iobuf_write_bignum(conv, temp0));
731 d0_iobuf_close(conv, &sz);
733 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
734 CHECK(d0_iobuf_write_packet(out, msg, msglen));
736 return d0_iobuf_close(out, outbuflen);
739 d0_iobuf_close(out, outbuflen);
743 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)
744 // first run: get 4^s, 4^s signature
747 // 3. send challenge challenge of SCHNORR_BITS
749 d0_iobuf_t *in = NULL;
750 d0_iobuf_t *out = NULL;
751 static unsigned char shabuf[2048];
754 // temps: temp0 order, temp0 signature check
757 REPLACING(schnorr_4_to_s); REPLACING(schnorr_H_4_to_s_signature);
759 REPLACING(schnorr_G);
765 USING(schnorr_4_to_s); USING(schnorr_H_4_to_s_signature);
768 USING(rsa_e); USING(rsa_n);
769 REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r);
771 in = d0_iobuf_open_read(inbuf, inbuflen);
772 out = d0_iobuf_open_write(outbuf, *outbuflen);
778 CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
779 CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
780 CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
782 CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
783 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, zero) >= 0);
784 CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, ctx->schnorr_G) < 0);
785 CHECK_ASSIGN(ctx->schnorr_H_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_4_to_s_signature));
786 CHECK(d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, zero) >= 0);
787 CHECK(d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, ctx->rsa_n) < 0);
789 // check signature of key (t = k^d, so, t^challenge = k)
790 CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_4_to_s_signature, ctx->rsa_e, ctx->rsa_n));
792 // we will actually sign SHA(4^s) to prevent a malleability attack!
793 CHECK(d0_bignum_mov(temp2, ctx->schnorr_4_to_s));
794 sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
795 if(sz > sizeof(shabuf))
797 CHECK(d0_longhash_destructive(temp2, shabuf, sz));
798 CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
800 // + 7 / 8 is too large, so let's mod it
801 CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
804 if(d0_bignum_cmp(temp0, temp1))
806 // accept the key anyway, but mark as failed signature! will later return 0 in status
807 CHECK(d0_bignum_zero(ctx->schnorr_H_4_to_s_signature));
811 CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
812 ctx->msglen = MSGSIZE;
813 CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
816 CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
818 CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
821 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
822 CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
823 CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
824 CHECK(d0_iobuf_write_bignum(out, temp0));
827 *status = !!d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, zero);
829 d0_iobuf_close(in, NULL);
830 return d0_iobuf_close(out, outbuflen);
833 d0_iobuf_close(in, NULL);
834 d0_iobuf_close(out, outbuflen);
838 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)
839 // 1. read challenge challenge of SCHNORR_BITS
840 // 2. reply with r + s * challenge mod order
842 d0_iobuf_t *in = NULL;
843 d0_iobuf_t *out = NULL;
845 // temps: 0 order, 1 prod, 2 y, 3 challenge
846 REPLACING(other_4_to_r);
847 USING(schnorr_G); USING(schnorr_s); USING(r);
849 in = d0_iobuf_open_read(inbuf, inbuflen);
850 out = d0_iobuf_open_write(outbuf, *outbuflen);
852 CHECK(d0_iobuf_read_bignum(in, temp3));
853 CHECK(d0_bignum_cmp(temp3, zero) >= 0);
854 CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
857 CHECK_ASSIGN(ctx->other_4_to_r, d0_iobuf_read_bignum(in, ctx->other_4_to_r));
858 CHECK(d0_bignum_cmp(ctx->other_4_to_r, zero) > 0);
859 CHECK(d0_bignum_cmp(ctx->other_4_to_r, ctx->schnorr_G) < 0);
861 // send response for schnorr ID scheme
862 // i.challenge. r + ctx->schnorr_s * temp3
863 CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
864 CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
865 CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
866 CHECK(d0_iobuf_write_bignum(out, temp2));
868 d0_iobuf_close(in, NULL);
869 return d0_iobuf_close(out, outbuflen);
872 d0_iobuf_close(in, NULL);
873 d0_iobuf_close(out, outbuflen);
877 WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *msg, size_t *msglen, BOOL *status)
878 // 1. read y = r + s * challenge mod order
879 // 2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
880 // (check using H(g^r) which we know)
882 d0_iobuf_t *in = NULL;
883 static unsigned char convbuf[1024];
884 d0_iobuf_t *conv = NULL;
887 // temps: 0 y 1 order
888 USING(challenge); USING(schnorr_G);
889 REPLACING(other_4_to_r);
891 in = d0_iobuf_open_read(inbuf, inbuflen);
893 CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
894 CHECK(d0_iobuf_read_bignum(in, temp0));
895 CHECK(d0_bignum_cmp(temp0, zero) >= 0);
896 CHECK(d0_bignum_cmp(temp0, temp1) < 0);
898 // verify schnorr ID scheme
899 // we need 4^temp0 (g^s)^-challenge
900 CHECK(d0_bignum_neg(temp1, ctx->challenge));
901 CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_4_to_s, temp1, ctx->schnorr_G));
902 CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
903 CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mod_mul(ctx->other_4_to_r, temp1, temp2, ctx->schnorr_G));
904 // hash must be equal to msghash
906 // hash it, hash it, everybody hash it
907 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
908 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
909 CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
910 CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
911 d0_iobuf_close(conv, &sz);
913 if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
915 // FAIL (not owned by player)
920 *status = !!d0_bignum_cmp(ctx->schnorr_H_4_to_s_signature, zero);
922 if(ctx->msglen <= *msglen)
923 memcpy(msg, ctx->msg, ctx->msglen);
925 memcpy(msg, ctx->msg, *msglen);
926 *msglen = ctx->msglen;
928 d0_iobuf_close(in, NULL);
932 d0_iobuf_close(in, NULL);
936 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
938 d0_iobuf_t *out = NULL;
939 static unsigned char convbuf[1024];
940 d0_iobuf_t *conv = NULL;
943 USING(schnorr_4_to_s);
945 out = d0_iobuf_open_write(outbuf, *outbuflen);
946 conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
948 CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_4_to_s));
949 CHECK(d0_iobuf_close(conv, &sz));
952 n = (*outbuflen / 4) * 3;
953 if(n > SHA_DIGESTSIZE)
955 CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
956 CHECK(d0_iobuf_conv_base64_out(out));
958 return d0_iobuf_close(out, outbuflen);
962 d0_iobuf_close(conv, &sz);
963 d0_iobuf_close(out, outbuflen);
967 BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
969 USING(r); USING(other_4_to_r); USING(schnorr_G);
971 // temps: temp0 result
972 CHECK(d0_bignum_mod_pow(temp0, ctx->other_4_to_r, ctx->r, ctx->schnorr_G));
973 return d0_longhash_destructive(temp0, outbuf, *outbuflen);
979 d0_blind_id_t *d0_blind_id_new(void)
981 d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
982 memset(b, 0, sizeof(*b));
986 void d0_blind_id_free(d0_blind_id_t *a)
988 d0_blind_id_clear(a);