diff --git a/src/secp256k1/src/bench_ecmult.c b/src/secp256k1/src/bench_ecmult.c --- a/src/secp256k1/src/bench_ecmult.c +++ b/src/secp256k1/src/bench_ecmult.c @@ -139,7 +139,11 @@ secp256k1_gej* pubkeys_gej; size_t scratch_size; + data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY); + scratch_size = secp256k1_strauss_scratch_size(POINTS) + STRAUSS_SCRATCH_OBJECTS*16; + data.scratch = secp256k1_scratch_space_create(data.ctx, scratch_size); data.ecmult_multi = secp256k1_ecmult_multi_var; + if (argc > 1) { if(have_flag(argc, argv, "pippenger_wnaf")) { printf("Using pippenger_wnaf:\n"); @@ -147,17 +151,19 @@ } else if(have_flag(argc, argv, "strauss_wnaf")) { printf("Using strauss_wnaf:\n"); data.ecmult_multi = secp256k1_ecmult_strauss_batch_single; + } else if(have_flag(argc, argv, "simple")) { + printf("Using simple algorithm:\n"); + data.ecmult_multi = secp256k1_ecmult_multi_var; + secp256k1_scratch_space_destroy(data.scratch); + data.scratch = NULL; } else { fprintf(stderr, "%s: unrecognized argument '%s'.\n", argv[0], argv[1]); - fprintf(stderr, "Use 'pippenger_wnaf', 'strauss_wnaf' or no argument to benchmark a combined algorithm.\n"); + fprintf(stderr, "Use 'pippenger_wnaf', 'strauss_wnaf', 'simple' or no argument to benchmark a combined algorithm.\n"); return 1; } } /* Allocate stuff */ - data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY); - scratch_size = secp256k1_strauss_scratch_size(POINTS) + STRAUSS_SCRATCH_OBJECTS*16; - data.scratch = secp256k1_scratch_space_create(data.ctx, scratch_size); data.scalars = malloc(sizeof(secp256k1_scalar) * POINTS); data.seckeys = malloc(sizeof(secp256k1_scalar) * POINTS); data.pubkeys = malloc(sizeof(secp256k1_ge) * POINTS); @@ -188,7 +194,9 @@ } } secp256k1_context_destroy(data.ctx); - secp256k1_scratch_space_destroy(data.scratch); + if (data.scratch != NULL) { + secp256k1_scratch_space_destroy(data.scratch); + } free(data.scalars); free(data.pubkeys); free(data.seckeys); diff --git a/src/secp256k1/src/ecmult.h b/src/secp256k1/src/ecmult.h --- a/src/secp256k1/src/ecmult.h +++ b/src/secp256k1/src/ecmult.h @@ -37,7 +37,8 @@ * Chooses the right algorithm for a given number of points and scratch space * size. Resets and overwrites the given scratch space. If the points do not * fit in the scratch space the algorithm is repeatedly run with batches of - * points. + * points. If no scratch space is given then a simple algorithm is used that + * simply multiplies the points with the corresponding scalars and adds them up. * Returns: 1 on success (including when inp_g_sc is NULL and n is 0) * 0 if there is not enough scratch space for a single point or * callback returns 0 diff --git a/src/secp256k1/src/ecmult_impl.h b/src/secp256k1/src/ecmult_impl.h --- a/src/secp256k1/src/ecmult_impl.h +++ b/src/secp256k1/src/ecmult_impl.h @@ -1084,6 +1084,33 @@ return res; } +/* Computes ecmult_multi by simply multiplying and adding each point. Does not + * require a scratch space */ +static int secp256k1_ecmult_multi_simple_var(const secp256k1_ecmult_context *ctx, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n_points) { + size_t point_idx; + secp256k1_scalar szero; + secp256k1_gej tmpj; + + secp256k1_scalar_set_int(&szero, 0); + secp256k1_gej_set_infinity(r); + secp256k1_gej_set_infinity(&tmpj); + /* r = inp_g_sc*G */ + secp256k1_ecmult(ctx, r, &tmpj, &szero, inp_g_sc); + for (point_idx = 0; point_idx < n_points; point_idx++) { + secp256k1_ge point; + secp256k1_gej pointj; + secp256k1_scalar scalar; + if (!cb(&scalar, &point, point_idx, cbdata)) { + return 0; + } + /* r += scalar*point */ + secp256k1_gej_set_ge(&pointj, &point); + secp256k1_ecmult(ctx, &tmpj, &pointj, &scalar, NULL); + secp256k1_gej_add_var(r, r, &tmpj, NULL); + } + return 1; +} + typedef int (*secp256k1_ecmult_multi_func)(const secp256k1_ecmult_context*, secp256k1_scratch*, secp256k1_gej*, const secp256k1_scalar*, secp256k1_ecmult_multi_callback cb, void*, size_t); static int secp256k1_ecmult_multi_var(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n) { size_t i; @@ -1102,6 +1129,9 @@ secp256k1_ecmult(ctx, r, r, &szero, inp_g_sc); return 1; } + if (scratch == NULL) { + return secp256k1_ecmult_multi_simple_var(ctx, r, inp_g_sc, cb, cbdata, n); + } max_points = secp256k1_pippenger_max_points(scratch); if (max_points == 0) { diff --git a/src/secp256k1/src/tests.c b/src/secp256k1/src/tests.c --- a/src/secp256k1/src/tests.c +++ b/src/secp256k1/src/tests.c @@ -2925,6 +2925,7 @@ test_ecmult_multi_pippenger_max_points(); scratch = secp256k1_scratch_create(&ctx->error_callback, 819200); test_ecmult_multi(scratch, secp256k1_ecmult_multi_var); + test_ecmult_multi(NULL, secp256k1_ecmult_multi_var); test_ecmult_multi(scratch, secp256k1_ecmult_pippenger_batch_single); test_ecmult_multi(scratch, secp256k1_ecmult_strauss_batch_single); secp256k1_scratch_destroy(scratch);