mirror of
https://github.com/jart/cosmopolitan.git
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120 lines
3.8 KiB
C
120 lines
3.8 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:4;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright The Mbed TLS Contributors │
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│ │
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│ Licensed under the Apache License, Version 2.0 (the "License"); │
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│ you may not use this file except in compliance with the License. │
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│ You may obtain a copy of the License at │
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│ │
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│ http://www.apache.org/licenses/LICENSE-2.0 │
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│ │
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│ Unless required by applicable law or agreed to in writing, software │
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│ distributed under the License is distributed on an "AS IS" BASIS, │
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│ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. │
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│ See the License for the specific language governing permissions and │
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│ limitations under the License. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.h"
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#include "libc/str/str.h"
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#include "third_party/mbedtls/bignum.h"
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#include "third_party/mbedtls/bignum_internal.h"
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#include "third_party/mbedtls/platform.h"
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typedef long long xmm_t __attribute__((__vector_size__(16), __aligned__(1)));
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static inline void shrd(mbedtls_mpi_uint *p, size_t n, size_t j, size_t m,
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char k)
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{
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mbedtls_mpi_uint x, y, *e, *f;
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f = p + m;
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if (n)
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{
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y = 0;
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x = p[j];
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e = p + n;
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for (; ++p < e; x = y)
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{
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y = p[j];
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p[-1] = x >> k | y << (biL - k);
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}
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p[-1] = x >> k;
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}
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while (p < f)
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*p++ = 0;
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}
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static inline void shld(mbedtls_mpi_uint *p, size_t n, size_t m, char k)
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{
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size_t i;
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mbedtls_mpi_uint x, y;
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MBEDTLS_ASSERT(n > m);
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i = n - 1;
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y = p[i - m];
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for (; i - m > 0; --i, y = x)
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{
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x = p[i - m - 1];
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p[i] = y << k | x >> (64 - k);
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}
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p[i] = y << k;
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while (i)
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{
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p[--i] = 0;
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}
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}
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/**
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* Performs left shift on big number: X <<= k
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*/
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int mbedtls_mpi_shift_l(mbedtls_mpi *X, size_t k)
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{
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int r;
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size_t b, n, m, l;
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MPI_VALIDATE_RET(X);
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l = mbedtls_mpi_bitlen(X);
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b = l + k;
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n = BITS_TO_LIMBS(b);
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m = k / biL;
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k = k % biL;
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if (n > X->n && (r = mbedtls_mpi_grow(X, n)))
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return r;
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if (k)
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{
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shld(X->p, X->n, m, k);
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}
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else if (m)
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{
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memmove(X->p + m, X->p, (X->n - m) * ciL);
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explicit_bzero(X->p, m * ciL);
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}
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return 0;
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}
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void ShiftRightPure(mbedtls_mpi_uint *p, size_t n, unsigned char k) {
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shrd(p, n, 0, n, k);
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}
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/**
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* Performs right arithmetic shift on big number: X >>= k
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*/
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int mbedtls_mpi_shift_r(mbedtls_mpi *X, size_t k)
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{
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size_t n;
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MPI_VALIDATE_RET(X);
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k = MIN(k, X->n * biL);
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n = k / biL;
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k = k % biL;
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if (k)
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{
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if (!n)
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ShiftRight(X->p, X->n, k);
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else
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shrd(X->p, X->n - n, n, X->n, k);
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}
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else if (n)
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{
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memmove(X->p, X->p + n, (X->n - n) * ciL);
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explicit_bzero(X->p + X->n - n, n * ciL);
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}
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return 0;
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}
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