diff options
author | Herbert Xu <herbert@gondor.apana.org.au> | 2023-08-04 17:24:34 +0800 |
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committer | Herbert Xu <herbert@gondor.apana.org.au> | 2023-08-11 19:19:27 +0800 |
commit | 2a598d0b2800aa23ba51adcf060cec524aaa63b2 (patch) | |
tree | b7c035f0fa57dab30af2768114f71f64230dac5c /lib/mpi/mpi-inv.c | |
parent | 9ae4577bc077a7e32c3c7d442c95bc76865c0f17 (diff) |
crypto: lib - Move mpi into lib/crypto
As lib/mpi is mostly used by crypto code, move it under lib/crypto
so that patches touching it get directed to the right mailing list.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'lib/mpi/mpi-inv.c')
-rw-r--r-- | lib/mpi/mpi-inv.c | 143 |
1 files changed, 0 insertions, 143 deletions
diff --git a/lib/mpi/mpi-inv.c b/lib/mpi/mpi-inv.c deleted file mode 100644 index 61e37d18f793..000000000000 --- a/lib/mpi/mpi-inv.c +++ /dev/null @@ -1,143 +0,0 @@ -/* mpi-inv.c - MPI functions - * Copyright (C) 1998, 2001, 2002, 2003 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, see <http://www.gnu.org/licenses/>. - */ - -#include "mpi-internal.h" - -/**************** - * Calculate the multiplicative inverse X of A mod N - * That is: Find the solution x for - * 1 = (a*x) mod n - */ -int mpi_invm(MPI x, MPI a, MPI n) -{ - /* Extended Euclid's algorithm (See TAOCP Vol II, 4.5.2, Alg X) - * modified according to Michael Penk's solution for Exercise 35 - * with further enhancement - */ - MPI u, v, u1, u2 = NULL, u3, v1, v2 = NULL, v3, t1, t2 = NULL, t3; - unsigned int k; - int sign; - int odd; - - if (!mpi_cmp_ui(a, 0)) - return 0; /* Inverse does not exists. */ - if (!mpi_cmp_ui(n, 1)) - return 0; /* Inverse does not exists. */ - - u = mpi_copy(a); - v = mpi_copy(n); - - for (k = 0; !mpi_test_bit(u, 0) && !mpi_test_bit(v, 0); k++) { - mpi_rshift(u, u, 1); - mpi_rshift(v, v, 1); - } - odd = mpi_test_bit(v, 0); - - u1 = mpi_alloc_set_ui(1); - if (!odd) - u2 = mpi_alloc_set_ui(0); - u3 = mpi_copy(u); - v1 = mpi_copy(v); - if (!odd) { - v2 = mpi_alloc(mpi_get_nlimbs(u)); - mpi_sub(v2, u1, u); /* U is used as const 1 */ - } - v3 = mpi_copy(v); - if (mpi_test_bit(u, 0)) { /* u is odd */ - t1 = mpi_alloc_set_ui(0); - if (!odd) { - t2 = mpi_alloc_set_ui(1); - t2->sign = 1; - } - t3 = mpi_copy(v); - t3->sign = !t3->sign; - goto Y4; - } else { - t1 = mpi_alloc_set_ui(1); - if (!odd) - t2 = mpi_alloc_set_ui(0); - t3 = mpi_copy(u); - } - - do { - do { - if (!odd) { - if (mpi_test_bit(t1, 0) || mpi_test_bit(t2, 0)) { - /* one is odd */ - mpi_add(t1, t1, v); - mpi_sub(t2, t2, u); - } - mpi_rshift(t1, t1, 1); - mpi_rshift(t2, t2, 1); - mpi_rshift(t3, t3, 1); - } else { - if (mpi_test_bit(t1, 0)) - mpi_add(t1, t1, v); - mpi_rshift(t1, t1, 1); - mpi_rshift(t3, t3, 1); - } -Y4: - ; - } while (!mpi_test_bit(t3, 0)); /* while t3 is even */ - - if (!t3->sign) { - mpi_set(u1, t1); - if (!odd) - mpi_set(u2, t2); - mpi_set(u3, t3); - } else { - mpi_sub(v1, v, t1); - sign = u->sign; u->sign = !u->sign; - if (!odd) - mpi_sub(v2, u, t2); - u->sign = sign; - sign = t3->sign; t3->sign = !t3->sign; - mpi_set(v3, t3); - t3->sign = sign; - } - mpi_sub(t1, u1, v1); - if (!odd) - mpi_sub(t2, u2, v2); - mpi_sub(t3, u3, v3); - if (t1->sign) { - mpi_add(t1, t1, v); - if (!odd) - mpi_sub(t2, t2, u); - } - } while (mpi_cmp_ui(t3, 0)); /* while t3 != 0 */ - /* mpi_lshift( u3, k ); */ - mpi_set(x, u1); - - mpi_free(u1); - mpi_free(v1); - mpi_free(t1); - if (!odd) { - mpi_free(u2); - mpi_free(v2); - mpi_free(t2); - } - mpi_free(u3); - mpi_free(v3); - mpi_free(t3); - - mpi_free(u); - mpi_free(v); - return 1; -} -EXPORT_SYMBOL_GPL(mpi_invm); |