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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Poly1305 authenticator algorithm, RFC7539
*
* Copyright (C) 2015 Martin Willi
*
* Based on public domain code by Andrew Moon and Daniel J. Bernstein.
*/
#include <crypto/internal/poly1305.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/unaligned.h>
static inline u64 mlt(u64 a, u64 b)
{
return a * b;
}
static inline u32 sr(u64 v, u_char n)
{
return v >> n;
}
static inline u32 and(u32 v, u32 mask)
{
return v & mask;
}
void poly1305_core_setkey(struct poly1305_key *key, const u8 *raw_key)
{
/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
key->r[0] = (get_unaligned_le32(raw_key + 0) >> 0) & 0x3ffffff;
key->r[1] = (get_unaligned_le32(raw_key + 3) >> 2) & 0x3ffff03;
key->r[2] = (get_unaligned_le32(raw_key + 6) >> 4) & 0x3ffc0ff;
key->r[3] = (get_unaligned_le32(raw_key + 9) >> 6) & 0x3f03fff;
key->r[4] = (get_unaligned_le32(raw_key + 12) >> 8) & 0x00fffff;
}
EXPORT_SYMBOL_GPL(poly1305_core_setkey);
void poly1305_core_blocks(struct poly1305_state *state,
const struct poly1305_key *key, const void *src,
unsigned int nblocks, u32 hibit)
{
u32 r0, r1, r2, r3, r4;
u32 s1, s2, s3, s4;
u32 h0, h1, h2, h3, h4;
u64 d0, d1, d2, d3, d4;
if (!nblocks)
return;
r0 = key->r[0];
r1 = key->r[1];
r2 = key->r[2];
r3 = key->r[3];
r4 = key->r[4];
s1 = r1 * 5;
s2 = r2 * 5;
s3 = r3 * 5;
s4 = r4 * 5;
h0 = state->h[0];
h1 = state->h[1];
h2 = state->h[2];
h3 = state->h[3];
h4 = state->h[4];
do {
/* h += m[i] */
h0 += (get_unaligned_le32(src + 0) >> 0) & 0x3ffffff;
h1 += (get_unaligned_le32(src + 3) >> 2) & 0x3ffffff;
h2 += (get_unaligned_le32(src + 6) >> 4) & 0x3ffffff;
h3 += (get_unaligned_le32(src + 9) >> 6) & 0x3ffffff;
h4 += (get_unaligned_le32(src + 12) >> 8) | (hibit << 24);
/* h *= r */
d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) +
mlt(h3, s2) + mlt(h4, s1);
d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) +
mlt(h3, s3) + mlt(h4, s2);
d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) +
mlt(h3, s4) + mlt(h4, s3);
d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) +
mlt(h3, r0) + mlt(h4, s4);
d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) +
mlt(h3, r1) + mlt(h4, r0);
/* (partial) h %= p */
d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff);
d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff);
d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff);
d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff);
h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff);
h1 += h0 >> 26; h0 = h0 & 0x3ffffff;
src += POLY1305_BLOCK_SIZE;
} while (--nblocks);
state->h[0] = h0;
state->h[1] = h1;
state->h[2] = h2;
state->h[3] = h3;
state->h[4] = h4;
}
EXPORT_SYMBOL_GPL(poly1305_core_blocks);
void poly1305_core_emit(const struct poly1305_state *state, void *dst)
{
u32 h0, h1, h2, h3, h4;
u32 g0, g1, g2, g3, g4;
u32 mask;
/* fully carry h */
h0 = state->h[0];
h1 = state->h[1];
h2 = state->h[2];
h3 = state->h[3];
h4 = state->h[4];
h2 += (h1 >> 26); h1 = h1 & 0x3ffffff;
h3 += (h2 >> 26); h2 = h2 & 0x3ffffff;
h4 += (h3 >> 26); h3 = h3 & 0x3ffffff;
h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff;
h1 += (h0 >> 26); h0 = h0 & 0x3ffffff;
/* compute h + -p */
g0 = h0 + 5;
g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff;
g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff;
g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff;
g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff;
/* select h if h < p, or h + -p if h >= p */
mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
g0 &= mask;
g1 &= mask;
g2 &= mask;
g3 &= mask;
g4 &= mask;
mask = ~mask;
h0 = (h0 & mask) | g0;
h1 = (h1 & mask) | g1;
h2 = (h2 & mask) | g2;
h3 = (h3 & mask) | g3;
h4 = (h4 & mask) | g4;
/* h = h % (2^128) */
put_unaligned_le32((h0 >> 0) | (h1 << 26), dst + 0);
put_unaligned_le32((h1 >> 6) | (h2 << 20), dst + 4);
put_unaligned_le32((h2 >> 12) | (h3 << 14), dst + 8);
put_unaligned_le32((h3 >> 18) | (h4 << 8), dst + 12);
}
EXPORT_SYMBOL_GPL(poly1305_core_emit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
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