cosmopolitan/libc/crypto/rijndaelinit.c

70 lines
3.1 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/bits.h"
#include "libc/bits/xmmintrin.internal.h"
#include "libc/crypto/rijndael.h"
#include "libc/dce.h"
#include "libc/str/internal.h"
#define ROR(w, k) (CheckUnsigned(w) >> (k) | (w) << (sizeof(w) * 8 - (k)))
static const uint8_t Rcon[11] = {0x8d, 0x01, 0x02, 0x04, 0x08, 0x10,
0x20, 0x40, 0x80, 0x1b, 0x36};
forceinline uint32_t SubRot(uint32_t t) {
uint32_t j;
for (j = 0; j < 4; j++) {
t = (t & -256) | kAesSbox[t & 255];
t = ROR(t, 8);
}
return t;
}
/**
* Computes key schedule for rijndael().
*
* @param ctx receives round keys
* @param n is 14 for AES-256, 12 for AES-192, and 10 for AES-128
* @param k1/k2 holds the master key
*/
void rijndaelinit(struct Rijndael *ctx, uint32_t n, aes_block_t k1,
aes_block_t k2) {
#define Nk (n - 6)
#define W(i) (ctx->rk[(i) / 4].u32[(i) % 4])
#define K(i) ((i) < 4 ? k1[i] : k2[(i)-4])
uint32_t i, t;
ctx->rk[0].xmm = k1;
ctx->rk[1].xmm = k2;
for (i = Nk; i < 4 * (n + 1); ++i) {
t = W(i - 1);
if (i % Nk == 0) {
t = ROR(t, 8);
t = SubRot(t);
t ^= Rcon[i / Nk];
} else if (Nk > 6 && i % Nk == 4) {
t = SubRot(t);
}
W(i) = W(i - Nk) ^ t;
}
XMM_DESTROY(k1);
XMM_DESTROY(k2);
}