147 lines
4.9 KiB
C
147 lines
4.9 KiB
C
/*
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* Copyright (c) 2012 Vincent Hanquez <vincent@snarc.org>
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the author nor the names of his contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <cryptonite_cpu.h>
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#include <aes/gf.h>
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#include <aes/x86ni.h>
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/* inplace GFMUL for xts mode */
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void cryptonite_aes_generic_gf_mulx(block128 *a)
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{
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const uint64_t gf_mask = cpu_to_le64(0x8000000000000000ULL);
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uint64_t r = ((a->q[1] & gf_mask) ? cpu_to_le64(0x87) : 0);
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a->q[1] = cpu_to_le64((le64_to_cpu(a->q[1]) << 1) | (a->q[0] & gf_mask ? 1 : 0));
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a->q[0] = cpu_to_le64(le64_to_cpu(a->q[0]) << 1) ^ r;
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}
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/*
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* GF multiplication with Shoup's method and 4-bit table.
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*
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* We precompute the products of H with all 4-bit polynomials and store them in
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* a 'table_4bit' array. To avoid unnecessary byte swapping, the 16 blocks are
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* written to the table with qwords already converted to CPU order. Table
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* indices use the reflected bit ordering, i.e. polynomials X^0, X^1, X^2, X^3
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* map to bit positions 3, 2, 1, 0 respectively.
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*
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* To multiply an arbitrary block with H, the input block is decomposed in 4-bit
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* segments. We get the final result after 32 table lookups and additions, one
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* for each segment, interleaving multiplication by P(X)=X^4.
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*/
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/* convert block128 qwords between BE and CPU order */
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static inline void block128_cpu_swap_be(block128 *a, const block128 *b)
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{
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a->q[1] = cpu_to_be64(b->q[1]);
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a->q[0] = cpu_to_be64(b->q[0]);
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}
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/* multiplication by P(X)=X, assuming qwords already in CPU order */
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static inline void cpu_gf_mulx(block128 *a, const block128 *b)
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{
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uint64_t v0 = b->q[0];
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uint64_t v1 = b->q[1];
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a->q[1] = v1 >> 1 | v0 << 63;
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a->q[0] = v0 >> 1 ^ ((0-(v1 & 1)) & 0xe100000000000000ULL);
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}
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static const uint64_t r4_0[] =
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{ 0x0000000000000000ULL, 0x1c20000000000000ULL
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, 0x3840000000000000ULL, 0x2460000000000000ULL
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, 0x7080000000000000ULL, 0x6ca0000000000000ULL
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, 0x48c0000000000000ULL, 0x54e0000000000000ULL
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, 0xe100000000000000ULL, 0xfd20000000000000ULL
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, 0xd940000000000000ULL, 0xc560000000000000ULL
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, 0x9180000000000000ULL, 0x8da0000000000000ULL
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, 0xa9c0000000000000ULL, 0xb5e0000000000000ULL
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};
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/* multiplication by P(X)=X^4, assuming qwords already in CPU order */
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static inline void cpu_gf_mulx4(block128 *a, const block128 *b)
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{
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uint64_t v0 = b->q[0];
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uint64_t v1 = b->q[1];
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a->q[1] = v1 >> 4 | v0 << 60;
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a->q[0] = v0 >> 4 ^ r4_0[v1 & 0xf];
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}
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/* initialize the 4-bit table given H */
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void cryptonite_aes_generic_hinit(table_4bit htable, const block128 *h)
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{
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block128 v, *p;
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int i, j;
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/* multiplication by 0 is 0 */
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block128_zero(&htable[0]);
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/* at index 8=2^3 we have H.X^0 = H */
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i = 8;
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block128_cpu_swap_be(&htable[i], h); /* in CPU order */
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p = &htable[i];
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/* for other powers of 2, repeat multiplication by P(X)=X */
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for (i = 4; i > 0; i >>= 1)
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{
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cpu_gf_mulx(&htable[i], p);
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p = &htable[i];
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}
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/* remaining elements are linear combinations */
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for (i = 2; i < 16; i <<= 1) {
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p = &htable[i];
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v = *p;
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for (j = 1; j < i; j++) {
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p[j] = v;
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block128_xor_aligned(&p[j], &htable[j]);
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}
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}
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}
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/* multiply a block with H */
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void cryptonite_aes_generic_gf_mul(block128 *a, const table_4bit htable)
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{
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block128 b;
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int i;
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block128_zero(&b);
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for (i = 15; i >= 0; i--)
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{
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uint8_t v = a->b[i];
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block128_xor_aligned(&b, &htable[v & 0xf]); /* high bits (reflected) */
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cpu_gf_mulx4(&b, &b);
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block128_xor_aligned(&b, &htable[v >> 4]); /* low bits (reflected) */
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if (i > 0)
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cpu_gf_mulx4(&b, &b);
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else
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block128_cpu_swap_be(a, &b); /* restore BE order when done */
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}
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}
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