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Path: blob/master/ext/libkirk/bn.c
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// Copyright 2007-2022 Segher Boessenkool <[email protected]>1// Licensed under the terms of the GNU GPL, either version 2 or version 32// https://www.gnu.org/licenses/old-licenses/gpl-2.0.txt3// https://www.gnu.org/licenses/gpl-3.0.html4// Updated and simplified for use by Kirk Engine - July 201156#include <string.h>7#include <stdio.h>89// Include definitions from kirk header10#include "kirk_engine.h"1112void bn_print(char *name, u8 *a, u32 n)13{14u32 i;1516printf("%s = ", name);1718for (i = 0; i < n; i++)19printf("%02x", a[i]);2021printf("\n");22}2324static void bn_zero(u8 *d, u32 n)25{26memset(d, 0, n);27}2829void bn_copy(u8 *d, u8 *a, u32 n)30{31memcpy(d, a, n);32}3334int bn_compare(u8 *a, u8 *b, u32 n)35{36u32 i;3738for (i = 0; i < n; i++) {39if (a[i] < b[i])40return -1;41if (a[i] > b[i])42return 1;43}4445return 0;46}4748static u8 bn_add_1(u8 *d, u8 *a, u8 *b, u32 n)49{50u32 i;51u32 dig;52u8 c;5354c = 0;55for (i = n - 1; i < n; i--) {56dig = a[i] + b[i] + c;57c = dig >> 8;58d[i] = dig;59}6061return c;62}6364static u8 bn_sub_1(u8 *d, u8 *a, u8 *b, u32 n)65{66u32 i;67u32 dig;68u8 c;6970c = 1;71for (i = n - 1; i < n; i--) {72dig = a[i] + 255 - b[i] + c;73c = dig >> 8;74d[i] = dig;75}7677return 1 - c;78}7980void bn_reduce(u8 *d, u8 *N, u32 n)81{82if (bn_compare(d, N, n) >= 0)83bn_sub_1(d, d, N, n);84}8586void bn_add(u8 *d, u8 *a, u8 *b, u8 *N, u32 n)87{88if (bn_add_1(d, a, b, n))89bn_sub_1(d, d, N, n);9091bn_reduce(d, N, n);92}9394void bn_sub(u8 *d, u8 *a, u8 *b, u8 *N, u32 n)95{96if (bn_sub_1(d, a, b, n))97bn_add_1(d, d, N, n);98}99100static const u8 inv256[0x80] = {1010x01, 0xab, 0xcd, 0xb7, 0x39, 0xa3, 0xc5, 0xef,1020xf1, 0x1b, 0x3d, 0xa7, 0x29, 0x13, 0x35, 0xdf,1030xe1, 0x8b, 0xad, 0x97, 0x19, 0x83, 0xa5, 0xcf,1040xd1, 0xfb, 0x1d, 0x87, 0x09, 0xf3, 0x15, 0xbf,1050xc1, 0x6b, 0x8d, 0x77, 0xf9, 0x63, 0x85, 0xaf,1060xb1, 0xdb, 0xfd, 0x67, 0xe9, 0xd3, 0xf5, 0x9f,1070xa1, 0x4b, 0x6d, 0x57, 0xd9, 0x43, 0x65, 0x8f,1080x91, 0xbb, 0xdd, 0x47, 0xc9, 0xb3, 0xd5, 0x7f,1090x81, 0x2b, 0x4d, 0x37, 0xb9, 0x23, 0x45, 0x6f,1100x71, 0x9b, 0xbd, 0x27, 0xa9, 0x93, 0xb5, 0x5f,1110x61, 0x0b, 0x2d, 0x17, 0x99, 0x03, 0x25, 0x4f,1120x51, 0x7b, 0x9d, 0x07, 0x89, 0x73, 0x95, 0x3f,1130x41, 0xeb, 0x0d, 0xf7, 0x79, 0xe3, 0x05, 0x2f,1140x31, 0x5b, 0x7d, 0xe7, 0x69, 0x53, 0x75, 0x1f,1150x21, 0xcb, 0xed, 0xd7, 0x59, 0xc3, 0xe5, 0x0f,1160x11, 0x3b, 0x5d, 0xc7, 0x49, 0x33, 0x55, 0xff,117};118119static void bn_mon_muladd_dig(u8 *d, u8 *a, u8 b, u8 *N, u32 n)120{121u32 dig;122u32 i;123124u8 z = -(d[n-1] + a[n-1]*b) * inv256[N[n-1]/2];125126dig = d[n-1] + a[n-1]*b + N[n-1]*z;127dig >>= 8;128129for (i = n - 2; i < n; i--) {130dig += d[i] + a[i]*b + N[i]*z;131d[i+1] = dig;132dig >>= 8;133}134135d[0] = dig;136dig >>= 8;137138if (dig)139bn_sub_1(d, d, N, n);140141bn_reduce(d, N, n);142}143144void bn_mon_mul(u8 *d, u8 *a, u8 *b, u8 *N, u32 n)145{146u8 t[512];147u32 i;148149bn_zero(t, n);150151for (i = n - 1; i < n; i--)152bn_mon_muladd_dig(t, a, b[i], N, n);153154bn_copy(d, t, n);155}156157void bn_to_mon(u8 *d, u8 *N, u32 n)158{159u32 i;160161for (i = 0; i < 8*n; i++)162bn_add(d, d, d, N, n);163}164165void bn_from_mon(u8 *d, u8 *N, u32 n)166{167u8 t[512];168169bn_zero(t, n);170t[n-1] = 1;171bn_mon_mul(d, d, t, N, n);172}173174static void bn_mon_exp(u8 *d, u8 *a, u8 *N, u32 n, u8 *e, u32 en)175{176u8 t[512];177u32 i;178u8 mask;179180bn_zero(d, n);181d[n-1] = 1;182bn_to_mon(d, N, n);183184for (i = 0; i < en; i++)185for (mask = 0x80; mask != 0; mask >>= 1) {186bn_mon_mul(t, d, d, N, n);187if ((e[i] & mask) != 0)188bn_mon_mul(d, t, a, N, n);189else190bn_copy(d, t, n);191}192}193194void bn_mon_inv(u8 *d, u8 *a, u8 *N, u32 n)195{196u8 t[512], s[512];197198bn_zero(s, n);199s[n-1] = 2;200bn_sub_1(t, N, s, n);201bn_mon_exp(d, a, N, n, t, n);202}203204205