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crypto: ge_bytes_hash_to_ec() added

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sowle 2021-01-09 17:48:57 +03:00
parent a98317cd52
commit 46d9895801
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GPG key ID: C07A24B2D89D49FC
3 changed files with 27 additions and 6 deletions
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16
src/crypto/crypto-ops.c
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@ -30,6 +30,7 @@
#include <stddef.h> #include <stddef.h>
#include "warnings.h" #include "warnings.h"
#include "crypto-ops.h" #include "crypto-ops.h"
#include "hash-ops.h" // for cn_fast_hash
DISABLE_VS_WARNINGS(4146 4244) DISABLE_VS_WARNINGS(4146 4244)
@ -3724,3 +3725,18 @@ void sc_invert(unsigned char* out, const unsigned char* z)
sc_mul(out, out, out); sc_mul(out, out, out);
sc_mul(out, out, z); sc_mul(out, out, z);
} }
// res = Hp(ge_bytes)
// where Hp = 8 * ge_fromfe_frombytes_vartime(cn_fast_hash(ge_bytes))
// In: ge_bytes -- points to 32 bytes data
void ge_bytes_hash_to_ec(ge_p3 *res, const unsigned char *ge_bytes)
{
unsigned char h[HASH_SIZE];
ge_p2 point;
ge_p1p1 point2;
cn_fast_hash(ge_bytes, 32, h);
ge_fromfe_frombytes_vartime(&point, &h[0]);
ge_mul8(&point2, &point);
ge_p1p1_to_p3(res, &point2);
}

2
src/crypto/crypto-ops.h
View file

@ -105,6 +105,8 @@ void ge_scalarmult_p3(ge_p3 *, const unsigned char *, const ge_p3 *);
void ge_double_scalarmult_precomp_vartime(ge_p2 *, const unsigned char *, const ge_p3 *, const unsigned char *, const ge_dsmp); void ge_double_scalarmult_precomp_vartime(ge_p2 *, const unsigned char *, const ge_p3 *, const unsigned char *, const ge_dsmp);
void ge_mul8(ge_p1p1 *, const ge_p2 *); void ge_mul8(ge_p1p1 *, const ge_p2 *);
void ge_fromfe_frombytes_vartime(ge_p2 *, const unsigned char *); void ge_fromfe_frombytes_vartime(ge_p2 *, const unsigned char *);
void ge_bytes_hash_to_ec(ge_p3 *, const unsigned char *);
void ge_p3_0(ge_p3 *h); void ge_p3_0(ge_p3 *h);
void ge_sub(ge_p1p1 *, const ge_p3 *, const ge_cached *); void ge_sub(ge_p1p1 *, const ge_p3 *, const ge_cached *);

15
src/crypto/crypto.cpp
View file

@ -303,11 +303,13 @@ namespace crypto {
PUSH_VS_WARNINGS PUSH_VS_WARNINGS
DISABLE_VS_WARNINGS(4200) DISABLE_VS_WARNINGS(4200)
struct rs_comm_entry struct rs_comm_entry
{ {
ec_point a, b; ec_point a, b;
}; };
struct rs_comm {
struct rs_comm
{
hash h; hash h;
struct rs_comm_entry ab[]; struct rs_comm_entry ab[];
}; };
@ -422,4 +424,5 @@ POP_VS_WARNINGS
sc_sub(&h, &h, &sum); sc_sub(&h, &h, &sum);
return sc_isnonzero(&h) == 0; return sc_isnonzero(&h) == 0;
} }
}
} // namespace crypto