Diffstat (limited to 'pwmanager/libcrypt/mpi/mpih-mul.c') (more/less context) (ignore whitespace changes)
| -rw-r--r-- | pwmanager/libcrypt/mpi/mpih-mul.c | 530 |
1 files changed, 530 insertions, 0 deletions
diff --git a/pwmanager/libcrypt/mpi/mpih-mul.c b/pwmanager/libcrypt/mpi/mpih-mul.c new file mode 100644 index 0000000..e1f6f58 --- a/dev/null +++ b/pwmanager/libcrypt/mpi/mpih-mul.c @@ -0,0 +1,530 @@ +/* mpih-mul.c - MPI helper functions + * Copyright (C) 1994, 1996, 1998, 1999, 2000, + * 2001, 2002 Free Software Foundation, Inc. + * + * This file is part of Libgcrypt. + * + * Libgcrypt is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as + * published by the Free Software Foundation; either version 2.1 of + * the License, or (at your option) any later version. + * + * Libgcrypt 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 Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA + * + * Note: This code is heavily based on the GNU MP Library. + * Actually it's the same code with only minor changes in the + * way the data is stored; this is to support the abstraction + * of an optional secure memory allocation which may be used + * to avoid revealing of sensitive data due to paging etc. + */ + +#include <config.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include "mpi-internal.h" +#include "longlong.h" +#include "g10lib.h" + +#define MPN_MUL_N_RECURSE(prodp, up, vp, size, tspace) \ + do { \ + if( (size) < KARATSUBA_THRESHOLD ) \ + mul_n_basecase (prodp, up, vp, size); \ + else \ + mul_n (prodp, up, vp, size, tspace); \ + } while (0); + +#define MPN_SQR_N_RECURSE(prodp, up, size, tspace) \ + do { \ + if ((size) < KARATSUBA_THRESHOLD) \ + _gcry_mpih_sqr_n_basecase (prodp, up, size); \ + else \ + _gcry_mpih_sqr_n (prodp, up, size, tspace); \ + } while (0); + + + + +/* Multiply the natural numbers u (pointed to by UP) and v (pointed to by VP), + * both with SIZE limbs, and store the result at PRODP. 2 * SIZE limbs are + * always stored. Return the most significant limb. + * + * Argument constraints: + * 1. PRODP != UP and PRODP != VP, i.e. the destination + * must be distinct from the multiplier and the multiplicand. + * + * + * Handle simple cases with traditional multiplication. + * + * This is the most critical code of multiplication. All multiplies rely + * on this, both small and huge. Small ones arrive here immediately. Huge + * ones arrive here as this is the base case for Karatsuba's recursive + * algorithm below. + */ + +static mpi_limb_t +mul_n_basecase( mpi_ptr_t prodp, mpi_ptr_t up, + mpi_ptr_t vp, mpi_size_t size) +{ + mpi_size_t i; + mpi_limb_t cy; + mpi_limb_t v_limb; + + /* Multiply by the first limb in V separately, as the result can be + * stored (not added) to PROD. We also avoid a loop for zeroing. */ + v_limb = vp[0]; + if( v_limb <= 1 ) { + if( v_limb == 1 ) + MPN_COPY( prodp, up, size ); + else + MPN_ZERO( prodp, size ); + cy = 0; + } + else + cy = _gcry_mpih_mul_1( prodp, up, size, v_limb ); + + prodp[size] = cy; + prodp++; + + /* For each iteration in the outer loop, multiply one limb from + * U with one limb from V, and add it to PROD. */ + for( i = 1; i < size; i++ ) { + v_limb = vp[i]; + if( v_limb <= 1 ) { + cy = 0; + if( v_limb == 1 ) + cy = _gcry_mpih_add_n(prodp, prodp, up, size); + } + else + cy = _gcry_mpih_addmul_1(prodp, up, size, v_limb); + + prodp[size] = cy; + prodp++; + } + + return cy; +} + + +static void +mul_n( mpi_ptr_t prodp, mpi_ptr_t up, mpi_ptr_t vp, + mpi_size_t size, mpi_ptr_t tspace ) +{ + if( size & 1 ) { + /* The size is odd, and the code below doesn't handle that. + * Multiply the least significant (size - 1) limbs with a recursive + * call, and handle the most significant limb of S1 and S2 + * separately. + * A slightly faster way to do this would be to make the Karatsuba + * code below behave as if the size were even, and let it check for + * odd size in the end. I.e., in essence move this code to the end. + * Doing so would save us a recursive call, and potentially make the + * stack grow a lot less. + */ + mpi_size_t esize = size - 1; /* even size */ + mpi_limb_t cy_limb; + + MPN_MUL_N_RECURSE( prodp, up, vp, esize, tspace ); + cy_limb = _gcry_mpih_addmul_1( prodp + esize, up, esize, vp[esize] ); + prodp[esize + esize] = cy_limb; + cy_limb = _gcry_mpih_addmul_1( prodp + esize, vp, size, up[esize] ); + prodp[esize + size] = cy_limb; + } + else { + /* Anatolij Alekseevich Karatsuba's divide-and-conquer algorithm. + * + * Split U in two pieces, U1 and U0, such that + * U = U0 + U1*(B**n), + * and V in V1 and V0, such that + * V = V0 + V1*(B**n). + * + * UV is then computed recursively using the identity + * + * 2n n n n + * UV = (B + B )U V + B (U -U )(V -V ) + (B + 1)U V + * 1 1 1 0 0 1 0 0 + * + * Where B = 2**BITS_PER_MP_LIMB. + */ + mpi_size_t hsize = size >> 1; + mpi_limb_t cy; + int negflg; + + /* Product H. ________________ ________________ + * |_____U1 x V1____||____U0 x V0_____| + * Put result in upper part of PROD and pass low part of TSPACE + * as new TSPACE. + */ + MPN_MUL_N_RECURSE(prodp + size, up + hsize, vp + hsize, hsize, tspace); + + /* Product M. ________________ + * |_(U1-U0)(V0-V1)_| + */ + if( _gcry_mpih_cmp(up + hsize, up, hsize) >= 0 ) { + _gcry_mpih_sub_n(prodp, up + hsize, up, hsize); + negflg = 0; + } + else { + _gcry_mpih_sub_n(prodp, up, up + hsize, hsize); + negflg = 1; + } + if( _gcry_mpih_cmp(vp + hsize, vp, hsize) >= 0 ) { + _gcry_mpih_sub_n(prodp + hsize, vp + hsize, vp, hsize); + negflg ^= 1; + } + else { + _gcry_mpih_sub_n(prodp + hsize, vp, vp + hsize, hsize); + /* No change of NEGFLG. */ + } + /* Read temporary operands from low part of PROD. + * Put result in low part of TSPACE using upper part of TSPACE + * as new TSPACE. + */ + MPN_MUL_N_RECURSE(tspace, prodp, prodp + hsize, hsize, tspace + size); + + /* Add/copy product H. */ + MPN_COPY (prodp + hsize, prodp + size, hsize); + cy = _gcry_mpih_add_n( prodp + size, prodp + size, + prodp + size + hsize, hsize); + + /* Add product M (if NEGFLG M is a negative number) */ + if(negflg) + cy -= _gcry_mpih_sub_n(prodp + hsize, prodp + hsize, tspace, size); + else + cy += _gcry_mpih_add_n(prodp + hsize, prodp + hsize, tspace, size); + + /* Product L. ________________ ________________ + * |________________||____U0 x V0_____| + * Read temporary operands from low part of PROD. + * Put result in low part of TSPACE using upper part of TSPACE + * as new TSPACE. + */ + MPN_MUL_N_RECURSE(tspace, up, vp, hsize, tspace + size); + + /* Add/copy Product L (twice) */ + + cy += _gcry_mpih_add_n(prodp + hsize, prodp + hsize, tspace, size); + if( cy ) + _gcry_mpih_add_1(prodp + hsize + size, prodp + hsize + size, hsize, cy); + + MPN_COPY(prodp, tspace, hsize); + cy = _gcry_mpih_add_n(prodp + hsize, prodp + hsize, tspace + hsize, hsize); + if( cy ) + _gcry_mpih_add_1(prodp + size, prodp + size, size, 1); + } +} + + +void +_gcry_mpih_sqr_n_basecase( mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t size ) +{ + mpi_size_t i; + mpi_limb_t cy_limb; + mpi_limb_t v_limb; + + /* Multiply by the first limb in V separately, as the result can be + * stored (not added) to PROD. We also avoid a loop for zeroing. */ + v_limb = up[0]; + if( v_limb <= 1 ) { + if( v_limb == 1 ) + MPN_COPY( prodp, up, size ); + else + MPN_ZERO(prodp, size); + cy_limb = 0; + } + else + cy_limb = _gcry_mpih_mul_1( prodp, up, size, v_limb ); + + prodp[size] = cy_limb; + prodp++; + + /* For each iteration in the outer loop, multiply one limb from + * U with one limb from V, and add it to PROD. */ + for( i=1; i < size; i++) { + v_limb = up[i]; + if( v_limb <= 1 ) { + cy_limb = 0; + if( v_limb == 1 ) + cy_limb = _gcry_mpih_add_n(prodp, prodp, up, size); + } + else + cy_limb = _gcry_mpih_addmul_1(prodp, up, size, v_limb); + + prodp[size] = cy_limb; + prodp++; + } +} + + +void +_gcry_mpih_sqr_n( mpi_ptr_t prodp, + mpi_ptr_t up, mpi_size_t size, mpi_ptr_t tspace) +{ + if( size & 1 ) { + /* The size is odd, and the code below doesn't handle that. + * Multiply the least significant (size - 1) limbs with a recursive + * call, and handle the most significant limb of S1 and S2 + * separately. + * A slightly faster way to do this would be to make the Karatsuba + * code below behave as if the size were even, and let it check for + * odd size in the end. I.e., in essence move this code to the end. + * Doing so would save us a recursive call, and potentially make the + * stack grow a lot less. + */ + mpi_size_t esize = size - 1; /* even size */ + mpi_limb_t cy_limb; + + MPN_SQR_N_RECURSE( prodp, up, esize, tspace ); + cy_limb = _gcry_mpih_addmul_1( prodp + esize, up, esize, up[esize] ); + prodp[esize + esize] = cy_limb; + cy_limb = _gcry_mpih_addmul_1( prodp + esize, up, size, up[esize] ); + + prodp[esize + size] = cy_limb; + } + else { + mpi_size_t hsize = size >> 1; + mpi_limb_t cy; + + /* Product H. ________________ ________________ + * |_____U1 x U1____||____U0 x U0_____| + * Put result in upper part of PROD and pass low part of TSPACE + * as new TSPACE. + */ + MPN_SQR_N_RECURSE(prodp + size, up + hsize, hsize, tspace); + + /* Product M. ________________ + * |_(U1-U0)(U0-U1)_| + */ + if( _gcry_mpih_cmp( up + hsize, up, hsize) >= 0 ) + _gcry_mpih_sub_n( prodp, up + hsize, up, hsize); + else + _gcry_mpih_sub_n (prodp, up, up + hsize, hsize); + + /* Read temporary operands from low part of PROD. + * Put result in low part of TSPACE using upper part of TSPACE + * as new TSPACE. */ + MPN_SQR_N_RECURSE(tspace, prodp, hsize, tspace + size); + + /* Add/copy product H */ + MPN_COPY(prodp + hsize, prodp + size, hsize); + cy = _gcry_mpih_add_n(prodp + size, prodp + size, + prodp + size + hsize, hsize); + + /* Add product M (if NEGFLG M is a negative number). */ + cy -= _gcry_mpih_sub_n (prodp + hsize, prodp + hsize, tspace, size); + + /* Product L. ________________ ________________ + * |________________||____U0 x U0_____| + * Read temporary operands from low part of PROD. + * Put result in low part of TSPACE using upper part of TSPACE + * as new TSPACE. */ + MPN_SQR_N_RECURSE (tspace, up, hsize, tspace + size); + + /* Add/copy Product L (twice). */ + cy += _gcry_mpih_add_n (prodp + hsize, prodp + hsize, tspace, size); + if( cy ) + _gcry_mpih_add_1(prodp + hsize + size, prodp + hsize + size, + hsize, cy); + + MPN_COPY(prodp, tspace, hsize); + cy = _gcry_mpih_add_n (prodp + hsize, prodp + hsize, tspace + hsize, hsize); + if( cy ) + _gcry_mpih_add_1 (prodp + size, prodp + size, size, 1); + } +} + + +/* This should be made into an inline function in gmp.h. */ +void +_gcry_mpih_mul_n( mpi_ptr_t prodp, + mpi_ptr_t up, mpi_ptr_t vp, mpi_size_t size) +{ + int secure; + + if( up == vp ) { + if( size < KARATSUBA_THRESHOLD ) + _gcry_mpih_sqr_n_basecase( prodp, up, size ); + else { + mpi_ptr_t tspace; + secure = gcry_is_secure( up ); + tspace = mpi_alloc_limb_space( 2 * size, secure ); + _gcry_mpih_sqr_n( prodp, up, size, tspace ); + _gcry_mpi_free_limb_space (tspace, 2 * size ); + } + } + else { + if( size < KARATSUBA_THRESHOLD ) + mul_n_basecase( prodp, up, vp, size ); + else { + mpi_ptr_t tspace; + secure = gcry_is_secure( up ) || gcry_is_secure( vp ); + tspace = mpi_alloc_limb_space( 2 * size, secure ); + mul_n (prodp, up, vp, size, tspace); + _gcry_mpi_free_limb_space (tspace, 2 * size ); + } + } +} + + + +void +_gcry_mpih_mul_karatsuba_case( mpi_ptr_t prodp, + mpi_ptr_t up, mpi_size_t usize, + mpi_ptr_t vp, mpi_size_t vsize, + struct karatsuba_ctx *ctx ) +{ + mpi_limb_t cy; + + if( !ctx->tspace || ctx->tspace_size < vsize ) { + if( ctx->tspace ) + _gcry_mpi_free_limb_space( ctx->tspace, ctx->tspace_nlimbs ); + ctx->tspace_nlimbs = 2 * vsize; + ctx->tspace = mpi_alloc_limb_space( 2 * vsize, + (gcry_is_secure( up ) + || gcry_is_secure( vp )) ); + ctx->tspace_size = vsize; + } + + MPN_MUL_N_RECURSE( prodp, up, vp, vsize, ctx->tspace ); + + prodp += vsize; + up += vsize; + usize -= vsize; + if( usize >= vsize ) { + if( !ctx->tp || ctx->tp_size < vsize ) { + if( ctx->tp ) + _gcry_mpi_free_limb_space( ctx->tp, ctx->tp_nlimbs ); + ctx->tp_nlimbs = 2 * vsize; + ctx->tp = mpi_alloc_limb_space( 2 * vsize, gcry_is_secure( up ) + || gcry_is_secure( vp ) ); + ctx->tp_size = vsize; + } + + do { + MPN_MUL_N_RECURSE( ctx->tp, up, vp, vsize, ctx->tspace ); + cy = _gcry_mpih_add_n( prodp, prodp, ctx->tp, vsize ); + _gcry_mpih_add_1( prodp + vsize, ctx->tp + vsize, vsize, cy ); + prodp += vsize; + up += vsize; + usize -= vsize; + } while( usize >= vsize ); + } + + if( usize ) { + if( usize < KARATSUBA_THRESHOLD ) { + _gcry_mpih_mul( ctx->tspace, vp, vsize, up, usize ); + } + else { + if( !ctx->next ) { + ctx->next = gcry_xcalloc( 1, sizeof *ctx ); + } + _gcry_mpih_mul_karatsuba_case( ctx->tspace, + vp, vsize, + up, usize, + ctx->next ); + } + + cy = _gcry_mpih_add_n( prodp, prodp, ctx->tspace, vsize); + _gcry_mpih_add_1( prodp + vsize, ctx->tspace + vsize, usize, cy ); + } +} + + +void +_gcry_mpih_release_karatsuba_ctx( struct karatsuba_ctx *ctx ) +{ + struct karatsuba_ctx *ctx2; + + if( ctx->tp ) + _gcry_mpi_free_limb_space( ctx->tp, ctx->tp_nlimbs ); + if( ctx->tspace ) + _gcry_mpi_free_limb_space( ctx->tspace, ctx->tspace_nlimbs ); + for( ctx=ctx->next; ctx; ctx = ctx2 ) { + ctx2 = ctx->next; + if( ctx->tp ) + _gcry_mpi_free_limb_space( ctx->tp, ctx->tp_nlimbs ); + if( ctx->tspace ) + _gcry_mpi_free_limb_space( ctx->tspace, ctx->tspace_nlimbs ); + gcry_free( ctx ); + } +} + +/* Multiply the natural numbers u (pointed to by UP, with USIZE limbs) + * and v (pointed to by VP, with VSIZE limbs), and store the result at + * PRODP. USIZE + VSIZE limbs are always stored, but if the input + * operands are normalized. Return the most significant limb of the + * result. + * + * NOTE: The space pointed to by PRODP is overwritten before finished + * with U and V, so overlap is an error. + * + * Argument constraints: + * 1. USIZE >= VSIZE. + * 2. PRODP != UP and PRODP != VP, i.e. the destination + * must be distinct from the multiplier and the multiplicand. + */ + +mpi_limb_t +_gcry_mpih_mul( mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t usize, + mpi_ptr_t vp, mpi_size_t vsize) +{ + mpi_ptr_t prod_endp = prodp + usize + vsize - 1; + mpi_limb_t cy; + struct karatsuba_ctx ctx; + + if( vsize < KARATSUBA_THRESHOLD ) { + mpi_size_t i; + mpi_limb_t v_limb; + + if( !vsize ) + return 0; + + /* Multiply by the first limb in V separately, as the result can be + * stored (not added) to PROD. We also avoid a loop for zeroing. */ + v_limb = vp[0]; + if( v_limb <= 1 ) { + if( v_limb == 1 ) + MPN_COPY( prodp, up, usize ); + else + MPN_ZERO( prodp, usize ); + cy = 0; + } + else + cy = _gcry_mpih_mul_1( prodp, up, usize, v_limb ); + + prodp[usize] = cy; + prodp++; + + /* For each iteration in the outer loop, multiply one limb from + * U with one limb from V, and add it to PROD. */ + for( i = 1; i < vsize; i++ ) { + v_limb = vp[i]; + if( v_limb <= 1 ) { + cy = 0; + if( v_limb == 1 ) + cy = _gcry_mpih_add_n(prodp, prodp, up, usize); + } + else + cy = _gcry_mpih_addmul_1(prodp, up, usize, v_limb); + + prodp[usize] = cy; + prodp++; + } + + return cy; + } + + memset( &ctx, 0, sizeof ctx ); + _gcry_mpih_mul_karatsuba_case( prodp, up, usize, vp, vsize, &ctx ); + _gcry_mpih_release_karatsuba_ctx( &ctx ); + return *prod_endp; +} + + |