uint8_t dsa_verify_bigint(const dsa_signature_t* s, const bigint_t* m, const dsa_ctx_t* ctx) { if(s->r.length_B==0 || s->s.length_B==0) { return DSA_SIGNATURE_FAIL; } if(bigint_cmp_u(&(s->r), &(ctx->domain.q))>=0 || bigint_cmp_u(&(s->s), &(ctx->domain.q))>=0) { return DSA_SIGNATURE_FAIL; } bigint_t w, u1, u2, v1, v2; uint8_t w_b[ctx->domain.q.length_B], u1_b[ctx->domain.q.length_B*2], u2_b[ctx->domain.q.length_B*2]; uint8_t v1_b[ctx->domain.p.length_B*2], v2_b[ctx->domain.p.length_B]; w.wordv = w_b; u1.wordv = u1_b; u2.wordv = u2_b; v1.wordv = v1_b; v2.wordv = v2_b; bigint_inverse(&w, &(s->s), &(ctx->domain.q)); bigint_mul_u(&u1, &w, m); bigint_reduce(&u1, &(ctx->domain.q)); bigint_mul_u(&u2, &w, &(s->r)); bigint_reduce(&u2, &(ctx->domain.q)); bigint_expmod_u(&v1, &(ctx->domain.g), &u1, &(ctx->domain.p)); bigint_expmod_u(&v2, &(ctx->pub), &u2, &(ctx->domain.p)); bigint_mul_u(&v1, &v1, &v2); bigint_reduce(&v1, &(ctx->domain.p)); bigint_reduce(&v1, &(ctx->domain.q)); if(bigint_cmp_u(&v1, &(s->r))==0) { return DSA_SIGNATURE_OK; } return DSA_SIGNATURE_FAIL; }
void testrun_performance_reduce_bigint(void){ printf_P(PSTR("\n=== performance measurement (reduce) ===\n")); unsigned i, j; bigint_t a,b,v; bigint_word_t v_w[192 * 2 / BIGINT_WORD_SIZE]; bigint_word_t a_w[192 * 2 / BIGINT_WORD_SIZE]; bigint_word_t b_w[192 * 2 / BIGINT_WORD_SIZE]; uint32_t time_a, time_b; int32_t time_diff; int16_t faster_percent; v.wordv = v_w; for(j = 0; j < 32; ++j){ do{ for(i = 0; i < 192 * 2 / BIGINT_WORD_SIZE; ++i){ ((uint8_t*)v_w)[i] = random(); } v.length_W = 192 * 2 / BIGINT_WORD_SIZE; v.info = 0; bigint_adjust(&v); }while(0); // printf_P(PSTR("candidate:\n")); // bigint_print_hex(&v); a.wordv = a_w; b.wordv = b_w; calibrateTimer(); // printf_P(PSTR("\n going to test optimized version: ...\n")); uart0_flush(); time_a = 0; for(i = 0; i < 16; ++i){ bigint_copy(&a, &v); startTimer(1); START_TIMER; bigint_reduce_p192(&a); STOP_TIMER; time_a += stopTimer(); } // printf_P(PSTR(" took: %"PRIu32" cycles\nresult:"), time); // bigint_print_hex(&a); // printf_P(PSTR("\n going to test not-optimized version: ...\n")); // uart0_flush(); time_b = 0; for(i = 0; i < 16; ++i){ bigint_copy(&b, &v); startTimer(1); START_TIMER; bigint_reduce(&b, &nist_curve_p192_p); STOP_TIMER; time_b += stopTimer(); } // printf_P(PSTR(" took: %"PRIu32" cycles\nresult:"), time); // bigint_print_hex(&b); time_diff = time_b - time_a; faster_percent = (time_diff * 100) / time_b; printf_P(PSTR(" delta: %7"PRId32" (%3"PRId16"%%) :-"), time_diff, faster_percent); if(bigint_cmp_u(&a, &b)){ printf_P(PSTR("(\n")); } else { printf_P(PSTR(")\n")); } uart0_flush(); } }