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surjectionproof: reduce stack usage

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This commit is contained in:
Andrew Poelstra
2019-04-30 22:46:05 +00:00
committed by Tim Ruffing
parent 68d937fe11
commit b8a3ff5f3b
3 changed files with 16 additions and 29 deletions
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19
src/modules/surjection/surjection_impl.h
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@@ -15,7 +15,7 @@
#include "scalar.h"
#include "hash.h"
SECP256K1_INLINE static void secp256k1_surjection_genmessage(unsigned char *msg32, secp256k1_ge *ephemeral_input_tags, size_t n_input_tags, secp256k1_ge *ephemeral_output_tag) {
SECP256K1_INLINE static void secp256k1_surjection_genmessage(unsigned char *msg32, const secp256k1_generator *ephemeral_input_tags, size_t n_input_tags, const secp256k1_generator *ephemeral_output_tag) {
/* compute message */
size_t i;
unsigned char pk_ser[33];
@@ -24,12 +24,12 @@ SECP256K1_INLINE static void secp256k1_surjection_genmessage(unsigned char *msg3
secp256k1_sha256_initialize(&sha256_en);
for (i = 0; i < n_input_tags; i++) {
secp256k1_eckey_pubkey_serialize(&ephemeral_input_tags[i], pk_ser, &pk_len, 1);
assert(pk_len == sizeof(pk_ser));
pk_ser[0] = 2 + (ephemeral_input_tags[i].data[63] & 1);
memcpy(&pk_ser[1], &ephemeral_input_tags[i].data[0], 32);
secp256k1_sha256_write(&sha256_en, pk_ser, pk_len);
}
secp256k1_eckey_pubkey_serialize(ephemeral_output_tag, pk_ser, &pk_len, 1);
assert(pk_len == sizeof(pk_ser));
pk_ser[0] = 2 + (ephemeral_output_tag->data[63] & 1);
memcpy(&pk_ser[1], &ephemeral_output_tag->data[0], 32);
secp256k1_sha256_write(&sha256_en, pk_ser, pk_len);
secp256k1_sha256_finalize(&sha256_en, msg32);
}
@@ -61,15 +61,18 @@ SECP256K1_INLINE static int secp256k1_surjection_genrand(secp256k1_scalar *s, si
return 1;
}
SECP256K1_INLINE static int secp256k1_surjection_compute_public_keys(secp256k1_gej *pubkeys, size_t n_pubkeys, const secp256k1_ge *input_tags, size_t n_input_tags, const unsigned char *used_tags, const secp256k1_ge *output_tag, size_t input_index, size_t *ring_input_index) {
SECP256K1_INLINE static int secp256k1_surjection_compute_public_keys(secp256k1_gej *pubkeys, size_t n_pubkeys, const secp256k1_generator *input_tags, size_t n_input_tags, const unsigned char *used_tags, const secp256k1_generator *output_tag, size_t input_index, size_t *ring_input_index) {
size_t i;
size_t j = 0;
for (i = 0; i < n_input_tags; i++) {
if (used_tags[i / 8] & (1 << (i % 8))) {
secp256k1_ge tmpge;
secp256k1_ge_neg(&tmpge, &input_tags[i]);
secp256k1_generator_load(&tmpge, &input_tags[i]);
secp256k1_ge_neg(&tmpge, &tmpge);
secp256k1_gej_set_ge(&pubkeys[j], &tmpge);
secp256k1_gej_add_ge_var(&pubkeys[j], &pubkeys[j], output_tag, NULL);
secp256k1_generator_load(&tmpge, output_tag);
secp256k1_gej_add_ge_var(&pubkeys[j], &pubkeys[j], &tmpge, NULL);
if (ring_input_index != NULL && input_index == i) {
*ring_input_index = j;
}