LXR linux/lib/crypto/poly1305-donna64.c

   1// SPDX-License-Identifier: GPL-2.0 OR MIT
   2/*
   3 * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
   4 *
   5 * This is based in part on Andrew Moon's poly1305-donna, which is in the
   6 * public domain.
   7 */
   8
   9#include <linux/kernel.h>
  10#include <asm/unaligned.h>
  11#include <crypto/internal/poly1305.h>
  12
  13typedef __uint128_t u128;
  14
  15void poly1305_core_setkey(struct poly1305_core_key *key, const u8 raw_key[16])
  16{
  17        u64 t0, t1;
  18
  19        /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  20        t0 = get_unaligned_le64(&raw_key[0]);
  21        t1 = get_unaligned_le64(&raw_key[8]);
  22
  23        key->key.r64[0] = t0 & 0xffc0fffffffULL;
  24        key->key.r64[1] = ((t0 >> 44) | (t1 << 20)) & 0xfffffc0ffffULL;
  25        key->key.r64[2] = ((t1 >> 24)) & 0x00ffffffc0fULL;
  26
  27        /* s = 20*r */
  28        key->precomputed_s.r64[0] = key->key.r64[1] * 20;
  29        key->precomputed_s.r64[1] = key->key.r64[2] * 20;
  30}
  31EXPORT_SYMBOL(poly1305_core_setkey);
  32
  33void poly1305_core_blocks(struct poly1305_state *state,
  34                          const struct poly1305_core_key *key, const void *src,
  35                          unsigned int nblocks, u32 hibit)
  36{
  37        const u8 *input = src;
  38        u64 hibit64;
  39        u64 r0, r1, r2;
  40        u64 s1, s2;
  41        u64 h0, h1, h2;
  42        u64 c;
  43        u128 d0, d1, d2, d;
  44
  45        if (!nblocks)
  46                return;
  47
  48        hibit64 = ((u64)hibit) << 40;
  49
  50        r0 = key->key.r64[0];
  51        r1 = key->key.r64[1];
  52        r2 = key->key.r64[2];
  53
  54        h0 = state->h64[0];
  55        h1 = state->h64[1];
  56        h2 = state->h64[2];
  57
  58        s1 = key->precomputed_s.r64[0];
  59        s2 = key->precomputed_s.r64[1];
  60
  61        do {
  62                u64 t0, t1;
  63
  64                /* h += m[i] */
  65                t0 = get_unaligned_le64(&input[0]);
  66                t1 = get_unaligned_le64(&input[8]);
  67
  68                h0 += t0 & 0xfffffffffffULL;
  69                h1 += ((t0 >> 44) | (t1 << 20)) & 0xfffffffffffULL;
  70                h2 += (((t1 >> 24)) & 0x3ffffffffffULL) | hibit64;
  71
  72                /* h *= r */
  73                d0 = (u128)h0 * r0;
  74                d = (u128)h1 * s2;
  75                d0 += d;
  76                d = (u128)h2 * s1;
  77                d0 += d;
  78                d1 = (u128)h0 * r1;
  79                d = (u128)h1 * r0;
  80                d1 += d;
  81                d = (u128)h2 * s2;
  82                d1 += d;
  83                d2 = (u128)h0 * r2;
  84                d = (u128)h1 * r1;
  85                d2 += d;
  86                d = (u128)h2 * r0;
  87                d2 += d;
  88
  89                /* (partial) h %= p */
  90                c = (u64)(d0 >> 44);
  91                h0 = (u64)d0 & 0xfffffffffffULL;
  92                d1 += c;
  93                c = (u64)(d1 >> 44);
  94                h1 = (u64)d1 & 0xfffffffffffULL;
  95                d2 += c;
  96                c = (u64)(d2 >> 42);
  97                h2 = (u64)d2 & 0x3ffffffffffULL;
  98                h0 += c * 5;
  99                c = h0 >> 44;
 100                h0 = h0 & 0xfffffffffffULL;
 101                h1 += c;
 102
 103                input += POLY1305_BLOCK_SIZE;
 104        } while (--nblocks);
 105
 106        state->h64[0] = h0;
 107        state->h64[1] = h1;
 108        state->h64[2] = h2;
 109}
 110EXPORT_SYMBOL(poly1305_core_blocks);
 111
 112void poly1305_core_emit(const struct poly1305_state *state, const u32 nonce[4],
 113                        void *dst)
 114{
 115        u8 *mac = dst;
 116        u64 h0, h1, h2, c;
 117        u64 g0, g1, g2;
 118        u64 t0, t1;
 119
 120        /* fully carry h */
 121        h0 = state->h64[0];
 122        h1 = state->h64[1];
 123        h2 = state->h64[2];
 124
 125        c = h1 >> 44;
 126        h1 &= 0xfffffffffffULL;
 127        h2 += c;
 128        c = h2 >> 42;
 129        h2 &= 0x3ffffffffffULL;
 130        h0 += c * 5;
 131        c = h0 >> 44;
 132        h0 &= 0xfffffffffffULL;
 133        h1 += c;
 134        c = h1 >> 44;
 135        h1 &= 0xfffffffffffULL;
 136        h2 += c;
 137        c = h2 >> 42;
 138        h2 &= 0x3ffffffffffULL;
 139        h0 += c * 5;
 140        c = h0 >> 44;
 141        h0 &= 0xfffffffffffULL;
 142        h1 += c;
 143
 144        /* compute h + -p */
 145        g0 = h0 + 5;
 146        c  = g0 >> 44;
 147        g0 &= 0xfffffffffffULL;
 148        g1 = h1 + c;
 149        c  = g1 >> 44;
 150        g1 &= 0xfffffffffffULL;
 151        g2 = h2 + c - (1ULL << 42);
 152
 153        /* select h if h < p, or h + -p if h >= p */
 154        c = (g2 >> ((sizeof(u64) * 8) - 1)) - 1;
 155        g0 &= c;
 156        g1 &= c;
 157        g2 &= c;
 158        c  = ~c;
 159        h0 = (h0 & c) | g0;
 160        h1 = (h1 & c) | g1;
 161        h2 = (h2 & c) | g2;
 162
 163        if (likely(nonce)) {
 164                /* h = (h + nonce) */
 165                t0 = ((u64)nonce[1] << 32) | nonce[0];
 166                t1 = ((u64)nonce[3] << 32) | nonce[2];
 167
 168                h0 += t0 & 0xfffffffffffULL;
 169                c = h0 >> 44;
 170                h0 &= 0xfffffffffffULL;
 171                h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffffULL) + c;
 172                c = h1 >> 44;
 173                h1 &= 0xfffffffffffULL;
 174                h2 += (((t1 >> 24)) & 0x3ffffffffffULL) + c;
 175                h2 &= 0x3ffffffffffULL;
 176        }
 177
 178        /* mac = h % (2^128) */
 179        h0 = h0 | (h1 << 44);
 180        h1 = (h1 >> 20) | (h2 << 24);
 181
 182        put_unaligned_le64(h0, &mac[0]);
 183        put_unaligned_le64(h1, &mac[8]);
 184}
 185EXPORT_SYMBOL(poly1305_core_emit);
 186