void crypto_ops::generate_signature(const hash &prefix_hash, const public_key &pub, const secret_key &sec, signature &sig) { lock_guard<mutex> lock(random_lock); ge_p3 tmp3; ec_scalar k; s_comm buf; #if !defined(NDEBUG) { ge_p3 t; public_key t2; assert(sc_check(&sec) == 0); ge_scalarmult_base(&t, &sec); ge_p3_tobytes(&t2, &t); assert(pub == t2); } #endif buf.h = prefix_hash; buf.key = pub; random_scalar(k); ge_scalarmult_base(&tmp3, &k); ge_p3_tobytes(&buf.comm, &tmp3); hash_to_scalar(&buf, sizeof(s_comm), sig.c); sc_mulsub(&sig.r, &sig.c, &sec, &k); }
void crypto_ops::generate_ring_signature(const hash &prefix_hash, const key_image &image, const public_key *const *pubs, size_t pubs_count, const secret_key &sec, size_t sec_index, signature *sig) { lock_guard<mutex> lock(random_lock); size_t i; ge_p3 image_unp; ge_dsmp image_pre; ec_scalar sum, k, h; rs_comm *const buf = reinterpret_cast<rs_comm *>(alloca(rs_comm_size(pubs_count))); assert(sec_index < pubs_count); #if !defined(NDEBUG) { ge_p3 t; public_key t2; key_image t3; assert(sc_check(&sec) == 0); ge_scalarmult_base(&t, &sec); ge_p3_tobytes(&t2, &t); assert(*pubs[sec_index] == t2); generate_key_image(*pubs[sec_index], sec, t3); assert(image == t3); for (i = 0; i < pubs_count; i++) { assert(check_key(*pubs[i])); } } #endif if (ge_frombytes_vartime(&image_unp, &image) != 0) { abort(); } ge_dsm_precomp(image_pre, &image_unp); sc_0(&sum); buf->h = prefix_hash; for (i = 0; i < pubs_count; i++) { ge_p2 tmp2; ge_p3 tmp3; if (i == sec_index) { random_scalar(k); ge_scalarmult_base(&tmp3, &k); ge_p3_tobytes(&buf->ab[i].a, &tmp3); hash_to_ec(*pubs[i], tmp3); ge_scalarmult(&tmp2, &k, &tmp3); ge_tobytes(&buf->ab[i].b, &tmp2); } else { random_scalar(sig[i].c); random_scalar(sig[i].r); if (ge_frombytes_vartime(&tmp3, &*pubs[i]) != 0) { abort(); } ge_double_scalarmult_base_vartime(&tmp2, &sig[i].c, &tmp3, &sig[i].r); ge_tobytes(&buf->ab[i].a, &tmp2); hash_to_ec(*pubs[i], tmp3); ge_double_scalarmult_precomp_vartime(&tmp2, &sig[i].r, &tmp3, &sig[i].c, image_pre); ge_tobytes(&buf->ab[i].b, &tmp2); sc_add(&sum, &sum, &sig[i].c); } } hash_to_scalar(buf, rs_comm_size(pubs_count), h); sc_sub(&sig[sec_index].c, &h, &sum); sc_mulsub(&sig[sec_index].r, &sig[sec_index].c, &sec, &k); }
//have to return s = a - cx //for each participant in the MG sig.. key rmsSign(key a, key c, key x) { key s; sc_mulsub(s.bytes, c.bytes, x.bytes, a.bytes); return s; }